Astronomy Unit 3 Packet

Astronomy Unit 3 Packet

If you have internet access, please check your school email and join the Astronomy Google Classroom. If you have not received an email the class code is 2yqx3xz.

If you do not have a computer but have internet service, please follow the directions below

for submitting your classwork.

You can take an image of the assignment and email it to me at [email protected].

Please make sure you do the following:

o Print (no cursive) very neatly in dark‐colored ink and

o Include your name on the assignment

Names ________________________________________________________________ Block _______

Constellation Presentation Rubric Google Slide Show

Submit Google Slide Show to [email protected]

Student

Check Points possible

Points Earned

Constellation Name 2

Appropriate Pictures on ALL Slides 4

Abbreviation (& Symbol if available) 2

Translation 2

Location of Constellation (R.A. & Declination) 2

Where on Earth do you need to live to see it? (Between latitudes…)

2

When is it best visible? (What month?) 2

Alpha Star (and Beta Star if required in packet) Be sure that ALL information is from the stars website provided on packet! If information is not provided use N/A.

Name ______ _______ Location on Chart(diagram) ______ _______ Spectral Class ______ _______ Evolutionary Stage ______ _______ Color ______ _______ Distance to Star ______ _______ Surface Temperature ______ _______ Luminosity ______ _______ Size (Diameter / Radius) ______ _______ Mass ______ _______ Other Information on Star ______ _______

11

Deep Sky (Messier) Objects (Google this information.) ______ Name (1pt) ______ Labeled Pictures of Each (2pt) ______ Description of Each (2pts)

5

Mythology & Other Stories (Google this information.) 4

3 Interesting Facts About Constellation (Google this information.)

3

Spelling / Grammar 2

Citations ______ Full Web Address for information (2pts) ______ Web Links under pictures (2pts)

4

Google Slide Show Total

X 2 = /90

*** If you are unable to complete this assignment due to internet issues, please contact me.

The Solar System: Comets 2 Day 5

KBO’s and Other Misfits Trans-Neptunian Objects (TNOs): All the objects on the frozen edge of the Solar

System beyond Neptune Includes:

o Kuiper Belt Objects (like Pluto) o Oort Cloud o Others

Kuiper Belt: A broad band of material beyond the orbit of Neptune Orbits between 30 – 50 to AUs Named after Gerard Kuiper Total mass (estimated) may exceed that of asteroid belt by a factor of 100+

Kuiper Belt Objects (KBOs) More than 600 known objects (as of 2003) 1st discovered in 1992 (1992 QB1) Gigantic balls of ice and rock Some are tens of km across , others are as

big a planets like Pluto Take 200 yrs or longer to orbit the Sun

Types of KBOs: Plutinos:

o Mini-Plutos o Have orbits like Pluto’s

Cubewanos o Have orbits that are more like circles

1992 QB1 1st discovered KBO Discovered by David Jewitt and graduate student Jane Luu Diameter= 200-250 km (125-155mi) Nearly circular orbit About 44 AU from Sun Orcus: Trans-Neptunian Object Discovered on Feb. 17, 2004 by Michael Brown, Chad Trujillo, and Robert Rabinowitz Diameter= 800-900 km

Quaoar “Kwah-o-ar” A KBO discovered 2002 by Michael Brown and Chadwick Trujillo Largest Kuiper object (to date) discovered since Pluto Diameter roughly 1200 km (1/2 size of Pluto) Orbits 42 AU from Sun (roughly 4 billion miles from Earth / 1 billion miles from Pluto) Orbit is nearly circular Ixion A KBO Discovered on May 22, 2001 Diameter= 650 km Varuna A KBO Near-circular orbit About 43 AU’s from Sun Orbital Period = 283 Earth years Shape= ellipsoid Odd Misfits Some objects are found between the Kuiper Belt and Oort Cloud These include:

o Sedna o 2003 UB313

Sedna New planetoid about the size of Pluto Located more than 2x as far from the Sun as Pluto Probably a huge ball of ice Appears reddish in color Orbital Period = 10,500 yrs Orbits between the Kuiper Belt and the Oort Cloud 2003 UB313 Appears to be larger than Pluto Sometimes referred to as the “10th planet” It nickname is “Xena” May be a scattered disc object, another type of TNO

Name ___________________________________________________________ Block ______ Comets (ID.A)

True/False Indicate whether the statement is true or false.

____ 1. Comets are not actually members of the solar system, but captured from

protostellar disk by the Sun.

____ 2. The Oort Cloud lies even farther out than the Kuiper Belt.

____ 3. Cometary dust tails lag behind the bluish ion tails as the comet rounds the Sun.

____ 4. Solar wind produces the tail of a comet.

Multiple Choice Identify the choice that best completes the statement or answers the question.

____ 5. The spacecraft that flew closest to Comet Halley in 1986 was:

a. the Russian Vega 2. d. NASA's Contour. b. ESA's Giotto. e. NASA's Cassini. c. NASA's Stardust.

____ 6. The tail of a comet always points: a. toward the Sun and disappears at perihelion. b. toward Earth and never varies. c. away from the Sun and disappears at perihelion. d. away from the Sun and becomes longest and brightest at perihelion. e. in the direction of the comet's motion.

____ 7. The nucleus of a comet is typically: a. a few meters in diameter. b. very durable, made of iron. c. a few kilometers in size, and very low in density. d. a few hundred kilometers across, and bright, shiny white from its ices. e. located between the orbits of Mars and Jupiter.

____ 8. Which of the following never hit the the earth? a. comets b. asteroids c. meteoroids d. All of these have hit us. e. None of these have ever impacted the earth in the past.

____ 9. The Oort Cloud is believed to be: a. a spherical cloud of cometary nuclei far beyond the Kuiper Belt. b. a flattened belt of cometary nuclei just beyond the orbit of Neptune. c. the circular disk of gas around the Sun's equator from which the planets formed. d. a grouping of asteroids and meteoroids between the orbits of Mars and Jupiter. e. the great nebula found just below the belt stars of Orion.

____ 10. Objects in the Kuiper belt: a. are in random orbits at all inclinations to the ecliptic. b. lie beyond the orbit of Neptune, and close to the ecliptic. c. are the sources of long-period comets. d. are dense, like the iron meteorites. e. have been known ever since the discovery of Triton in 1846.

____ 11. Which of the following does not fall into the category of interplanetary debris? a. comets d. Trojan asteroids b. meteoroids e. Kuiper Belt bodies c. rings around the jovians

____ 12. Long-period comets are believed to originally come from: a. the asteroid belt. d. the satellite system of Jupiter. b. the Kuiper belt. e. the interstellar medium. c. the Oort cloud.

____ 13. Which of the following is not icy in composition? a. comet nuclei d. asteroids b. rings of Saturn e. most Jovian satellites c. the polar regions of Mars

____ 14. The orbits of most comets: a. lie almost entirely beyond the orbit of Neptune. b. have perihelions inside the orbit of Mercury. c. have aphelions in the Kuiper belt. d. are smaller than the orbit of Comet Halley, with a 76-year period. e. are open, going out into interstellar space, and thus never return.

____ 15. Which of the following have an icy composition? a. most asteroids d. the rings of Saturn b. meteoroids e. Both C and D are correct. c. most comets

____ 16. Which of these bodies are most likely to break up over time? a. asteroids in the main belt d. Kuiper Belt bodies b. Jovian satellites e. Trojan asteroids c. comet nuclei

____ 17. A comet might be expected to suddenly become brighter if __. a. all the icy material in the nucleus has evaporated b. the tail passes through the corona of the Sun c. A solar flare occurs and quickly heats up the nucleus d. Its perihelion takes it outside the orbit of the Earth

____ 18. The “dirty snowball” portion of a comet is called the __. a. whipple portion c. comab. nucleus d. tail

____ 19. What is the composition of a comet’s nucleus? a. dust & rock particles c. carbon dioxide and water ice b. methane and ammonia d. all of these

Completion Complete each statement. 20. The ______________________ Belt bodies orbit beyond Neptune, but like the planets

stay close to the ecliptic plane and in fairly circular orbits.

21. The ______________________ Cloud is a vast, spherical array of long period comet nuclei far beyond the orbit of Neptune.

22. Comet orbits all have ___________________ eccentricity compared to the asteroids.

23. The curved, yellow _________ tail lags behind the blue tail as the comet rounds the Sun.

24. While Kuiper Belt bodies are often larger than any asteroid, we think their density will be lower due to presence of a lot of _________________________

25. The ________________________ of a comet is not usually visible from Earth’s surface.

The Solar System: Meteoroids, Meteors, & Meteorites Day 6 Interstellar Matter: Meteoroids

Meteoroids: A piece of rocky interplanetary matter smaller than 100 m across Are more common that asteroids or comets

Small Meteoroids Are mainly rocky remains of broken-up comets Large Meteoroids Diameter = few cm + Are not associated with comets Most likely strayed from asteroid belt Most have orbits that intersect asteroid belt Responsible for many craters on Moon, Mercury, Venus, Mars and some Jovian moons Meteor Material Travel at speeds of tens of kilometers per second when they streak into the atmosphere Most are small, ranging from a grain of sand to a pea-sized pebble Almost all of them disintegrate in the atmosphere before reaching the ground Meteors A sudden, quick streak of light produced by the friction of meteor material entering the

Earth’s atmosphere “Shooting stars” or “Falling stars”

Comets & Meteors As comets travel around the Sun bits of dust are shed as the comet is

vaporized by the Sun a little at time This material forms a swarm of debris scattered along the comet’s

orbit Meteoroid Swarms: A group of dust to pebble-sized particles (micrometeoroids) that move

in nearly the same path as the parent comet Meteor Showers: Occur when Earth’s orbit intersects a young meteoroid swarm Since the Earth crosses the comet’s orbit at the same time each year,

each meteor shower is predictably visible at the same time of the year, year after year.

One can see many meteors Are named for their radiant (constellation from whose direction they

appear to come) About 8 major showers per year and many minor showers Most are best viewed between midnight and dawn Best viewed on clear moonless nights (new moon phase) Most have a peak activity period that last between several hours and a couple of days Orionids: Typically peak around Oct. 21st Associated with Halley’s comet At peak observers can typically see as many as 20

meteors per hour under dark skies Among the fastest-moving meteors (66km/s or

148,000 mph) Typically have long glowing tails (due to speed)

History of the Orionids: 1839 - Discovered by Edward C. Herrick 1864 - 1st precise observations made by

Alexander Herschel 1892 – 1st measurements of peak rates 1911 – Charles Oliver speculated the

association with Halley’s Comet, although it was several years before this connection was accepted by astronomers

Geminids: Typically peak in mid-December One can often see 120 – 150 meteors per hour Average speed – 35 km/s (78,000 mph) Often leave yellowish-colored tails as they zip through the atmosphere

History of the Geminids: 1862- 1st observed 1983 – Source identified as the asteroid 3200 Phaethon Theories on Origin:

o Asteroid struck another asteroid leaving a cloud of debris o 3200 Phaethon is a comet in disguise – one that has traveled pass the Sun

so many times that all of its ices have been melted away leaving just a darkened, rock-encrusted remnant

Leonids: Associated with Comet Tuttle Visible in November Typically have speeds around 72 km/s Fireballs Especially bright meteors that can be seen even in the daytime Meteorites: A meteoroid that impacts the Earth’s surface Meteoroids less than 1 meter across (1 ton in mass) generally burn up in Earth’s

atmosphere Impact Crater on Earth Currently approx. 100 craters larger than 0.1 km in diameter Most heavily eroded Image – The 1.2 Diameter Barringer Crater in Arizona was formed

about 25,000 years ago. Identifying Craters Most identified by satellite photography Impact Events On average occur relatively infrequently Smaller ones occur more frequently than larger ones

Tunguska June 30, 1908 in Siberia Rocky meteoroid approx. 30m across Exploded above ground w/ 10 megatons of energy Heard from hundreds of km Increased atmospheric dust levels all across the Northern Hemisphere Types of Meteorites: Aerolites Siderites Tektites Carbonaceous Chondrites

Aerolites: Stony Composition similar to Earth’s rocks Largely silicate materials Size – pebbles to boulders Siderites: Metallic Composed of mainly iron and nickel Show characteristic crystalline patterns

when their surface are cut Are believed to have come from the

core of differentiated asteroids that broke apart

Aerolites & Siderites: Are believed to be material left over from the formation of the Solar System Tektites: Glassy stones Resemble volcanic rocks Are younger than aerolites and siderites Believed to have been formed during impacts with the Moon

or another planet

Carbonaceous Chondrites: Black or dark gray Similar composition to carbonaceous asteroids Contain fragile organic molecules

Meteorite Ages: Most are 4.4 to 4.6 billion years old = age of the solar system

Importance of Meteorites: • Contain pristine material from the formation of the solar nebula • Some contain amino acids from the interstellar medium • Can come from the Moon, and Mars, as well as the asteroid belt

Left Blank on Purpose

Name _______________________________________________ Block _______ Meteoroids (ID.A) True/False Indicate whether the statement is true or false.

____ 1. Carbonaceous chondrite meteorite contain fragile organic molecules.

____ 2. Meteor showers are the result of collisions between asteroids.

____ 3. Some meteorites are believed to have come from Mars and the Moon.

____ 4. Siderites are the “stony” type of meteorites.

____ 5. A meteor can be seen for weeks or even months at a time.

____ 6. A meteor shower results each time Earth passes through a meteoroid

swarm.

____ 7. The Leonid meteor shower occurs on November 16th each year and is a product of earth passing through the meteoroid swarm of comet Tuttle.


____ 8. Which of the following does not fall into the category of interplanetary

debris? a. comets b. rings around the jovians c. Trojan asteroids d. meteoroids e. Kuiper Belt bodies

____ 9. Iron meteorites are believed to come from:

a. the core of a differentiated asteroid, now broken up. b. the crust of a differentiated asteroid, now broken up. c. a broken up cometary nucleus. d. debris from the Kuiper Belt. e. interstellar space.

____ 10. Meteor showers are:

a. usually annual events, as the orbits again intersect. b. caused by the earth passing near the orbit of an earth-grazing asteroid. c. caused by the earth passing near the orbit of an old short-period comet. d. Both A and B are correct. e. Both A and C are correct.

____ 11. Meteorites are important because:

a. they contain pristine material from the solar nebula. b. some contain amino acids from the interstellar medium. c. some come from the Moon and Mars, as well as the asteroid belt.

d. All of the above are true. e. None of the above are true.

____ 12. The famous Barringer meteor crater is found in:

a. Australia. d. Siberia. b. Arizona. e. Antarctica. c. Canada.

____ 13. A meteorite __.

a. has the potential to become a meteor b. is like a meteor, except smaller c. is a meteor that strikes the surface of the Earth d. becomes a meteoroid if it is captured by the gravitational field of a planet

____ 14. The radiant of a meteor shower ___.

a. is always directly overhead (at zenith) b. is fixed with respect to the constellation c. is opposite the direction of the Earth’s motion through space d. depends on the number of meteors that fall each hour

____ 15. The term “shooting star” refers to __.

a. a visible meteor c. as asteroid b. meteoric dust d. a planetary moon

____ 16. The names of meteor showers is derived from the positions of the __ in

the sky, which tend to be the same, year after year, for any meteor shower. a. originating comets c. radiants b. originating asteroids d. focal points

Completion Complete each statement.

17. Meteoric material dates the formation of the solar system at about ______

billion years.

18. A solid body from the outer solar system that arrives intact on the earth's surface is called a __________________________

19. Streaks of light made when small debris hits our atmosphere are called __________________________

20. The _______________________ Meteor Crater located in Arizona is 1.2 km in diameter and was formed about 25,000 years ago.

Name ___________________________________________ Block ___________ Interplanetary Matter (ID.A) True/False Indicate whether the sentence or statement is true or false.

____ 1. A comets tail always points toward the sun.

____ 2. Solar wind produces the tail of a comet.

____ 3. Comets are the source of some of the water here on Earth.

____ 4. Siderites are the “stony” type of meteorites.

Multiple Choice Identify the letter of the choice that best completes the statement or answers the question.

____ 5. The Oort Cloud is thought to be __.

a. the cloud of gas and dust from which our solar system formed b. a cloud of debris that occasionally encounters the Earth, causing a meteor showerc. a cloud of comets surrounding the Solar System d. a cloud of asteroids moving between the orbits of Mars and Jupiter

____ 6. What is the defining property of the Trojan asteroids?

a. They have orbits at the distance of Jupiter and 60o ahead of or behind it. b. They have orbits that cross the orbit of the Earth. c. They have a composition that is the most primitive of all asteroids. d. They have a composition that is metallic and rocky, indicating they originated

from a differentiated body. ____ 7. What part of a comet is not usually visible from Earth’s surface?

a. Dust tail c. Nucleus b. Ion tail d. Coma

____ 8. Which of the following falls into the category of interplanetary debris?

a. large and small asteroids, comets, and grains of dust b. dust only c. asteroids only d. comet only

____ 9. Where are asteroids generally found in the solar system?

a. Beyond the orbit of Uranus b. Between the orbits of Mars and Jupiter c. Among the orbits of the terrestrial planets d. Among the orbits of the jovian planets

____ 10. A comet might be expected to suddenly become brighter if __.

a. all the icy material in the nucleus has evaporated b. the tail passes through the corona of the Sun c. A solar flare occurs and quickly heats up the nucleus d. Its perihelion takes it outside the orbit of the Earth

____ 11. A meteorite __. a. has the potential to become a meteor b. is like a meteor, except smaller c. is a meteor that strikes the surface of the Earth d. becomes a meteoroid if it is captured by the gravitational field of a planet

____ 12. The radiant of a meteor shower ___.

a. is always directly overhead (at zenith) b. is fixed with respect to the constellation c. is opposite the direction of the Earth’s motion through space d. depends on the number of meteors that fall each hour

____ 13. The term “shooting star” refers to __.

a. a visible meteor c. as asteroid b. meteoric dust d. a planetary moon

____ 14. The Kuiper belt __.

a. lies outside the orbit of Neptune b. lies between the orbits of Mars and Jupiter c. is an intense region of radiation around Jupiter d. is where comets go to die

____ 15. According to one theory, tektites come from __.

a. the Sun c. comets b. the Moon and Mars d. beyond the Milky Way galaxy

____ 16. ___ asteroids are dark in color and contain a significant amount of ice

and other volatile substances. a. Carbonaceous c. Trojan b. Silicate d. Earth-crossing

____ 17. This asteroid passed within 120,000 km of the Earth and was not

detected until 3 days later. a. Icarius b. 2002 MN c. Ceres d. Haley’s

____ 18. What would be the result of a 1 km asteroid striking the Earth’s

surface. a. devastation in an area of hundred of kilometers b. devastation would compare to 100x all the nuclear bombs in the world going off

at the same time c. it would be an extinction level event d. all of these

____ 19. What is the name of the largest known asteroid?

a. Icarius b. 2002 MN c. Ceres d. Haley’s ____ 20. What is the composition of a comet’s nucleus?

a. dust & rock particles b. methane and ammonia c. carbon dioxide and water ice d. all of these

The Solar System: Formation of the Solar System Day 7 Planetary System Formation Until mid-1990’s, theories concentrated on our own solar system since there were no other examples

of planetary systems in which to test their ideas. Extrasolar Planets: Planets orbiting stars other than the Sun Currently 200+ Very little info New Planetary System: Seem to have properties quite different from our own May require us to rethink our concepts of how stars and planets form Planetary Models Must adhere to 9 known facts

The Solar System: Model Requirements

Fact 1 Each planet is relatively isolated in space.

o Independent o Progressively larger distance from the central sun o Not bunched together

Fact 2 The orbits of the planets are nearly circular (have a low eccentricity)

o Exceptions: Mercury & Pluto Fact 3 All the planets orbit lie roughly in the same plane (ecliptic)

o Sun’s rotational equator lies nearly in this plane o Orbits are within few degrees o Slight exceptions: Mercury & Pluto

Fact 4 The direction in which the planets orbit the Sun (counterclockwise as viewed from above Earth’s

North Pole) is the same as the direction in which the Sun rotates on its axis Fact 5 The direction in which most planets rotate on their axis is roughly the same as the direction in which

the Sun rotates on its axis o Exceptions: Venus, Uranus, Pluto

Fact 6 The direction in which most of the known moons revolve about their parent planet is the same as

the direction in which the planet rotates on its axis. o Exception: Triton (Neptune’s moon)

Fact 7 Our planetary system is highly differentiated Composition varies roughly with distance from the Sun

o Dense, metal-rich planets in the inner regions

o Giant, hydrogen-rich planets in the outer regions o (Terrestrial planets differ from Jovian planets)

Fact 8 Asteroids are very old and exhibit a range of properties not characteristic of other terrestrial or the

jovian planets or their moons o Asteroids share the bulk orbital properties of the planets o Asteroids appear to be made of primitive, un-evolved material o Meteorites are the oldest rocks known

Fact 9 Comets are primitive, icy fragments that do not necessarily orbit in the ecliptic plane and reside

primarily at large distances from the Sun, in the Kuiper Belt and the Oort Cloud. Other Facts: Planets contain about 90% of solar system’s angular momentum Planet and asteroid rotation rates are similar (5-15 hours) unless tides slow them down Planet distances obey the Titus-Bode “Law” Despite their differences the bodies of the solar system seem to form a common family

o Seem to have originated at the same time o Few indications exist of later captures from other stars or interstellar space

Titus-Bode “Law” A rough rule that predicts the spacing of the planets in the Solar System Relates the mean distance of the planets from the sun to a simple progression of numbers What Does This Mean? High degree of order within solar system Components too uniform to be the result of random chaotic events Must have been a one-time event – a single formation billions of years ago What Don’t We Know? Why orbits should be roughly circular, coplanar, and prograde What Theories Must Explain Provide strong reasons for the observed planetary characteristics yet be flexible enough to allow for

and explain the deviations Age of Our Solar System 4.6 billion years Based on radiometric dating:

o Oldest meteorites o Earth and lunar rocks

The Solar System: Nebular Contraction

Nebula Large cloud of interstellar dust and gas Nebular Contraction Theory Holds that planets within the solar nebula are by-products of the process of star formation Gases collected to form Sun and planets

Nebula Theory Nebula + External Force = collapsing & spinning nebula Conservation of Angular Momentum 1796 – Pierre Simon de Laplace Nebular must spin faster as it contracts Nebula Shape Increase in rotation causes nebula’s shape to change as it shrinks Centrifugal Forces Due to rotation Opposes contraction in direction perpendicular to the rotational axis Results: Nebula contracts forming accretion disk (solar nebula) Nebular Theory Faults While Laplace’s description of the collapse and flattening of the solar nebula

was essentially correct, we now know that a disk of gas would not form clumps of matter that would subsequently evolve into planets.

The Solar System: Condensation Theory

Condensation Theory Theory of Planetary Formation Included dust particles Interstellar Dust: Microscopic dust grains found in the space between stars Accumulations of the ejected matter of many long-dead stars Interstellar Dust Formation: Probably formed in the cool atmospheres of old stars, then grew by

accumulating more atoms and molecules from the interstellar gas Result interstellar space is littered with tiny chunks of ice and rock matter typically having

diameters of about 10-5m. Importance of Dust: Helps cool warm matter by efficiently radiating heat away in the form of infrared radiation

o When molecules cool they: Move more slowly Reduce the internal pressure Allowing the nebula to collapse more easily

Dust grains greatly speed up the process of collecting enough atoms to form a planet

Acted as condensation nuclei platforms to which other particles could attach and form larger particles of matter

Step 1: Collapse of very large (about 100,000 AU) gas and

dust cloud o Collapse initiated by external force (another

passing cloud, or exploding star) o As it collapses its slight rotation increases

Conservation of angular momentum Observed today in the

orbits of planets o Dust is a key element

It speeds cooling, allowing collapse Step 2: Centrifugal Effects:

o Outer parts of nebular flatten into a disk o Central part of nebula forms Sun o Planets will eventually form in disk and the

Sun is part of the disk Step 3: Gas Molecules and Dust Grains in Circular Orbits

o Those on noncircular orbits collide with particles and eventually dampen noncircular motion o Large scale motion is parallel, circular orbits

Step 4: Collapsing Gas and Dust Heats Through Collisions

o Around 3000K everything in gaseous form o Hydrogen (about 90%) and Helium (about 10%) make

up most of nebula o Silicates and iron compounds about 1%

Step 5: Nebula Cools

o Outer parts cooling off more than inner parts (that are close to hot proto-sun)

o Metal stuff can condense (freeze) at high temperatures while volatile stuff condenses at lower temperatures

o Local temperature and density depends on distance from proto-sun

o At Jupiter temperature cool enough to freeze water Inner Regions Too hot for ices Many abundant elements – (Si, Fe, Mg, Al) + O to produce

variety of rocky materials Longer for temps. to drop to allow condensation of particles Formed inner planets Underrepresented in light materials (gases)

Beyond 5 AU’s Temp. low enough to allow condensation of several abundant gases = water vapor, ammonia, &

methane These formed outer planets Step 5:

o Chondrules of material with highest freezing temperature form and become incorporated in material of lower freezing temperature

o Planets will also differentiate later on: Heavy metals in core – lighter near surface

Step 6: Gas and Dust Particles in Parallel, Circular Orbits

o Small eddies collide at low velocities o Condensation nuclei stick together by gravity and electrostatic forces (accretion) o Coalescing particles form bodies rotating in same direction as revolution with similar

rotation rates (planetesimals) o Gravity tends to divide nebula into ring-shaped zones (later form planets)

Planetesimals Objects size of small moons Millions of them at first Planetismal’s growth rate increases due to increase in mass and gravity Proto-planets Are accumulations of matter that would eventually evolve into planets Form from planetesimals colliding and merging Strong gravitational fields produce many high-speed collisions Collisions lead to fragmentation Fragments swept up by proto-planets Step 7: Massive Planetesimals Pull in Nearby Nebula (Core-Accretion Theory)

o Some can form mini-solar nebulae to form moons o Jupiter and Saturn have a lot of water ice mass

Sweep up a lot of Hydrogen and Helium o Uranus and Neptune less so

Step 7: Alternative Theory Gravitational Instability Theory:

o Outer portions of cloud collapse o Jovian planets would have smaller rocky cores

Step 8: Icy planetesimals near Jupiter and Saturn flung out of solar system

o Those near Uranus and Neptune flung to large orbits (Oort Cloud) o Giant-Planet Migration (Jupiter moves inward)

Step 9: Early Sun has magnetic field and spews out ions

o Ions dragged along by rotating magnetic field o Dragging ions brake the Sun

o Also accretion disks like solar nebula o Tend to transfer angular momentum outward

Step 10: Proto-Sun core gets to about 10 million degrees Kelvin

o Starts fusion – Sun turns on o T-Tauri winds sweep out rest of nebula that was not

already incorporated into the planets

The Solar System: Asteroids & Comets Asteroids Planetesimals that failed to aggregate into a planet Oort Cloud Produced by interplanetary fragments kicked out of solar system by gravitational pull of jovian

planets Kuiper Belt Objects Strong support to condensation theory Icy Planetesimals Planetary matter thrown into inner solar system Source of water and volatile gases on Earth

The Solar System: Conclusion

Condensation Theory Allows for all 9 facts and deviations known Is the most widely accepted idea of solar system formation AKA – Solar Nebular Theory

o Is supported by observations of dusty disks around the equators of young, condensing stars

Name ______________________________________________ Block__________ Formation of the Solar System (ID.A) True/False Indicate whether the statement is true or false.

____ 1. Any successful model for the formation of the solar system must

explain why the orbits of the planets have low eccentricities.

____ 2. In the solar nebular theory, the dusty disk condensing around the Sun's equator became the ecliptic plane in which the planets then formed.

____ 3. In addition to revolving around the Sun counter clockwise, most planets also rotate on their axis counter clockwise.

____ 4. The axial tilts of the planets are all close to 23.5 degrees, like our own.

____ 5. The most widely excepted model of the solar system formation is the solar nebular theory.

____ 6. The orbit of most planets is highly elliptical in shape.

____ 7. The direction in which most planets rotate is the same direction in which they revolve around the Sun.

____ 8. The formation of the solar system is thought to be the product of many random events.

____ 9. The direction in which most moons revolve around a planet is the same direction in which the parent planet spins on its axis.


____ 10. What happens when the solar nebula contracts?

a. It flattens out into the ecliptic plane around the Sun's equator. b. It spins faster due to conservation of angular momentum. c. It heats up due to collisions. d. all of the above e. It falls into the Sun.

____ 11. Which planet by itself contains the majority of mass of all the planets?

a. Jupiter d. Venus b. Saturn e. Uranus c. the earth

____ 12. What was the primary role of dust in the formation of the solar system? a. Dust veiled the process by which our solar system formed. b. Dust acted as condensation nuclei- platforms to which other particles could attach

and form larger particles of matter. c. The Sun formed from a vast spinning cloud consisting only of dust. d. Dust provided the radioactive elements that initially heated the Sun.

____ 13. What is the name of the theory that is currently used to describe the

formation of the solar system? a. nebular theory b. collision theory c. close-encounter theory d. condensation theory


14. All planets lie in orbits close to the ___________________________ plane.

15. Meteoric material dates the formation of the solar system at about __________

billion years.

16. The second most abundant element in the solar system is _________________

17. The only planet whose perihelion carries it inside the orbit of another planet is ______________________

18. The age of the solar system is determined with _________________________ dating.

19. Most of the angular momentum of the solar system is found in the _________________________________________

20. The solar nebular theory has been supported by observation of dusty disks around the ___________________________ of young, condensing stars.

The Solar System: Extrasolar Planetary Systems Day 9

Exoplanetary Systems • None of these planetary systems look anything like our own solar system • Most are single planet systems • Most have planets that are large and gaseous • Most have planets that orbit close to the parent star. Final Count (as of January 2010) • Total 424 exoplanets around 357 stars

o 49 multi-planet systems o Stars mostly main-sequence (sun-like), few neutron stars

1st Extrasolar System: • Discovered in 1994 by Swiss astronomers using 1.9m telescope at Haute-Provence

Observatory in France • Star 51 Pegasi Star 51 Pegasi: • Near twin to our sun • 40 ly away Upsilon Andromedae: • Nearby sun-like star • Triple-planet system • Planet masses – 0.7, 2.1, and 4.3x Jupiter with orbital semi-

major axes of 0.06, 0.83 and 2.6 AU, respectively HD 209458: • Solar-type star • 0.6 Jupiter-mass companion that orbits 7 million km (0.05 AU) and has a density of 200

kg/m3 (hot gas giant) 55 Cancri • Has at least 5 planets

Extrasolar Planetary Systems: Detecting Extrasolar Planets Made Possible By: • Improvements in telescopes and detector technology • Computerized data analysis How Detected?: • Not able to image them at this time • By analysis of light from parent star (Doppler Shift)

o “Wobbling” of parent star due to gravitational tug of planet

Doppler Effect/Shift: • Wobbling causes small fluctuations in star’s radial

velocity and can be measured using the Doppler effect Gravitational Tug • Increases with mass of planet and planet’s

closeness to star

Extrasolar Planetary Systems: Exoplanets Planetary Properties: • Easy to determine:

o Planet Mass o Size of Orbit o Period of Revolution

• Harder to determine: o Density o Composition (but can perhaps detect IR radiation or radio waves) o Rotation (but can perhaps detect diurnal variations) o Atmosphere (but one has been detected from Absorption lines in starlight)

Exoplanet Trends • Most are larger than Jupiter • Most orbit in short orbits close to their stars “Hot Jupiters”: • Observed planets that are comparable in mass to Jupiter however, have orbits that are

much smaller and more eccentric • Since they orbit closer to their parent star, they are hotter Low-Mass Planets • Not surprising that we have not observed any --- selection effect Selection Effect • Lightweight planets, or planets far from their apparent star, simply don’t produce

large enough velocity fluctuations to be detected Is Our Solar System Unusual? • Planetary systems are apparently fairly common, but those discovered so far don’t look

like our own • We have only recently discovered some terrestrial-like planets

Name ________________________________________________ Block ________

Extrasolar Solar Systems (ID.A) True/False Indicate whether the statement is true or false.

____ 1. We would expect other planets beyond our own solar system to orbit

the equators of their home stars, as our own planets orbit the Sun.

____ 2. In some cases, we have seen extrasolar planets pass in front of their stars.

____ 3. Astronomers have not discovered extra-solar planetary systems similar to our own.

____ 4. We have discovered other planets similar to our terrestrial planets.

____ 5. Most extra-solar planetary systems, that we know of, are composed of a sun-like star and a single Jupiter-like planet.


____ 6. So far, beyond the solar system the extrasolar planets found have been

mostly: a. large jovians orbiting solar-type stars about where our jovians are found. b. large jovians with terrestrial-type orbits. c. terrestrials very close to their star, and transiting its disk. d. terrestrials with very elongated, distant orbits like comets. e. brown dwarfs much more massive than Jupiter.

____ 7. Most of the extrasolar planets found so far were detected by:

a. noting the drop in the star's light as the planet transits its disk. b. imaging them with the HST in the infrared, where they are easier to stop. c. noting the Doppler shifts of the star as the planet orbits it from side to side. d. receiving radio transmissions from them, much like Jupiter emits. e. detecting the oxygen in their atmospheres spectroscopically.

____ 8. Which statement about extrasolar planets found to date is false?

a. All are jovians, comparable to Jupiter or Saturn. b. Most are found by Doppler shifts of their stars, due to their gravity. c. Some have yet been seen to actually cross the disk of their stars. d. Most have orbital periods of more than a year. e. Some are so close to their stars that their periods are just a few days.

____ 9. Most of the extra-solar planets observed so far have masses

comparable to the mass of ____ and orbits that take them ___ to their parent star. a. Jupiter, far c. Earth, far b. Jupiter, close d. Earth, close


10. Most of the planets found orbiting other stars are similar to Jupiter, but

_________________________ in temperature.

11. The extrasolar planets are found mainly by observing the __________________________________ shifts of their stars.

Short Answer

12. Describe two ways of detecting extrasolar planets.

13. How do most of the new solar systems just discovered compare to our own?

Astronomy Unit 4 Packet

Part 1

If you have internet access, please check your school email and join the Astronomy Google Classroom. If you have not received an email the class code is 2yqx3xz.

If you do not have a computer but have internet service, please follow the directions below

for submitting your classwork.

You can take an image of the assignment and email it to me at [email protected].

Please make sure you do the following:

o Print (no cursive) very neatly in dark‐colored ink and

o Include your name on the assignment

Left Blank

Earth-Moon System: Planet Earth Day 1

Orbital Properties Max. Distance

from Sun: (Aphelion)

152 million km (94.5 million miles)

Rotation Period (Solar Day)

24 hrs 1.025 Earth days

Min. Distance from Sun:

(Perihelion)

146 million km (91 million miles)

Rotation Period (Sidereal Day)

23 hrs 56 min

Orbital Semi-major Axis: 1 AU Revolution Period

about the Sun: 365 days 5 hrs

Avg. Orbital

Velocity: 24.077 km/s

Inclination: 1.850o (5.65

o to

Sun’s equator) Tilt of Axis: 23.27

o

Perihelion vs. Aphelion Avg. Distance from Sun = 1 AU Perihelion (Closest) Aphelion (Farthest) Effects of Rotation Causes Earth to bulge at the equator Flattens the poles Effect of Rotation on Earth 40 km difference in diameters Earth’s diameter is about 12,800 km Precession This equatorial bulge causes earth to wobble on its axis like a

top Surface Gravity Strength of the gravitational force at the body’s surface Earth = 1.0 Escape Velocity Speed required for any object to escape forever from the body’s gravitational pull Earth = 11km/s or 25,000 mph

Earth’s Age Oldest rocks on Earth are 4 byo Most meteors are 4.6 byo Oldest Moon rocks are 4.6 byo None are older From this information we conclude that the Earth is 4.6 byo.

Physical Properties

Planetary Symbol:

Diameter: 12,753 km (7,926 miles) Surface Gravity: 9.78 m/s

2

(Earth = 1)

Mass: 5.98x1024

kg

(6.5 x 1021

tons)Temperature

Range: -89

o C to 57.7

o C

( -128o F to 136

o F)

Density: 5,515 kg/m3

Average Surface Temperature (K): 287K

Surface Area: 5.1 x 108 km

2 Satellites: 1

Planet Earth: Earth’s Interior

Earth’s Structure Core Mantle Crust Core 2 parts

o Solid inner core o Liquid outer core

Iron and nickel Mantle Thickest layer Contains plastic-like layer (asthenosphere) Iron, magnesium, silicates Crust Thin, brittle outer layer Mainly silicate material

Planet Earth: The Hydrosphere Hydrosphere Approx. 70 % of the surface area 97% of water in the oceans Average depth 3.6 km 3 % in lakes, rivers, glaciers, and clouds Regulates temperature on Earth Essential to LIFE!

Planet Earth: Tides Tides The ocean rises and falls twice a day Most areas have tides of about 1 meter Some areas have 20 m tides The Cause of Tides The Moon’s and Sun’s gravity cause tides Tides Different points on Earth have different

gravitational forces from the Moon Tides are caused by the DIFFERENCE in forces

across the Earth Tides The Earth is deformed by the Moon’s and Sun’s gravity

(tidal effects) This is in addition to the rotation effects Is Earth Actually Distorted By The Moon? Yes – the diameter of Earth changes by a few centimeters The oceans are affected more Spring Tide At times, the Sun and Moon are aligned Alignment produces bigger tides (large tidal

range) Occur during full and new moons

Neap Tides The Moon, Earth and Sun are at right angles (at

quarter moons) A lower than average tide occurs (sm. tidal range) Forces partially cancel Rotation & Tidal Forces Tides distort the Earth Friction and rotation cause the bulge to be

slightly ahead of the Moon The off-center bulge slows the rotation Longer Days? Fossils indicated that 500 mya a day was about

22 hours The Moon is moving farther away and the Earth

is slowing down Eventually Earth will be “tidally locked” with the

Moon “Tidal Locking” Synchronous motion Rotation period is precisely equal to its orbital

period around another body Tides on the Moon The gravity from the Earth causes tides on the Moon The tidal forces have stopped the Moon’s rotation The Moon is “tidally locked” with the Earth

Planet Earth: The Atmosphere Atmosphere Gas envelope surrounding the Earth The air we breathe Protection from high energy EM radiation Protection from meteors

Primary Atmosphere H & He Gases common in the early solar system Since then most have escaped from Earth Secondary Atmosphere Volcanic out-gassing N, CO2, SO2, H2O vapor, methane Most of these gases are now trapped in rocks Current Atmosphere Early plant life changed some of the CO2 into O2 Most of the CO2 is trapped in rocks Ozone layer formed from the Oxygen

Current Atmospheric Compo. 78 % Nitrogen 21 % Oxygen 0.9 % Argon 0.03 % Carbon Dioxide Water Vapor 0.1 to 3 % Oxygen Unique in the Solar System Due to direct consequence of life on Earth

Atmospheric Layers Troposphere

o Lowest layer = <15 km o Weather zone o Air cools and thins with altitude

Stratosphere o 15 km - 40 km o Ozone layer

Mesosphere o 40 km – 90 km

Thermosphere o 90 km

Exosphere

Earth’s Atmosphere: The Ozone Layer In upper stratosphere, oxygen is found as O3 This is called ozone Ozone is opaque to most UV and X-ray photons Blocks UV radiation Temperature of Earth Without the atmosphere, Earth would have an average temperature of -23oC The average temperature is currently

about 10oC A Balance Between Radiation & Absorption Energy Absorbed = Energy Radiated

(on avg.) The Greenhouse Effect Most of the Sun’s energy is visible

light Most of the Earth’s radiated energy is

infrared Visible light pass through the

atmosphere of Earth The light is absorbed by the Earth The Earth warms up and radiates infrared energy The Greenhouse Effect Most of the infrared energy is blocked

by the water vapor and CO2 The Earth absorbs the extra infrared

energy The Earth heats up a bit more Earth is about 40 K hotter than the

Moon because of our atmosphere The Greenhouse Effect: Runaway Greenhouse Effect The amount of CO2 in the atmosphere

increases 4% per decade Global temperatures are slowly rising The global climate is being altered by

humans

Runaway Greenhouse Effect Most of the CO2 on Earth is contained in rocks Heating the rocks causes the release of the CO2 Burning fossil fuels CO2 blocks infrared light Destruction of the oceans

Planet Earth: The Magnetosphere Magnetosphere Far above atmosphere High energy particles are trapped by the magnetic field Also protects Earth from high energy particles Aurora The magnetic field traps particles from the solar wind The particles strike atmosphere near the poles Northern & Southern lights result Formation of Magnetic Field The magnetic field is caused by convection inside the

Earth’s core Convection Heating a gas (or liquid) cause it to expand Hot material rises – cold material sinks Convection Is Important Inside the Earth’s outer core

o Forms magnetic field Inside the Earth’s mantle

o Drives Earth’s plate tectonics In the Earth’s atmosphere

o Weather and turbulence In the Earth’s Oceans

o Effects on weather and temperature Earth’s Magnetic Field Changes polarity about every 700,000 years

Planet Earth: Planetary Geology Surface Features on Earth Earth is geologically alive The surface is “young” and changing Plate Tectonics Active geological sites are only found

on well-defined lines These lines are at the edge of geologic

plates Geologic Processes Occurring On Earth Volcanism Seismic Activity Erosion …

Name __________________________________________________ Block ______ The Earth (ID.A) Multiple Choice Identify the letter of the choice that best completes the statement or answers the question.

____ 1. Earth’s escape velocity is approximately __.

a. 17,500 mph b. 25,000 mph c. 3,700 mph d. Mach 1

____ 2. What will cause Polaris to lose its place as the “North Star”? a. Stellar parallax c. Proper Motion b. Precession d. Retrograde motion

____ 3. The thick, solid layer between the crust and the core of the Earth is called the __. a. differentiation layer c. polar cap b. mantle d. temperate layer

____ 4. An extremely high tide occurs when the phase of the Moon is __. a. full b. new c. crescent d. full or new

____ 5. The troposphere is __. a. the lowest level of the Earth’s atmosphereb. a level about midway between the Earth’s surface and the edge of the

atmospherec. the highest level of the Earth’s atmosphered. the layer within the Earth where plate tectonics occurs most noticeably

____ 6. Tides on the Earth are primarily due to the mutual gravitational attraction between the Earth and __. a. the Moon b. the Sun c. Jupiter d. None of these

____ 7. If the Moon were covered with water, the number of tidal bulges on it would be __. a. one b. two c. none

____ 8. What is the primary ingredient in the Earth’s atmosphere? a. nitrogen b. oxygen c. carbon dioxide d. hydrogen

____ 9. Which of the following regions of the Earth appears to be unique (not found on any other body in the solar system)? a. atmosphere c. mantleb. hydrosphere d. magnetosphere

____ 10. __ is the spinning of Earth on its axis. a. Rotation b. Declination c. Revolution d. Azimuth

____ 11. Name two places on Earth where convection is operating on a large scale, creating natural phenomena that are important features for life on Earth. a. in the atmosphere and the mantle c. in the crust and the exosphere b. in the two Van Allen belts d. all of the above

____ 12. The northern lights owe their existence to __. a. Earth’s magnetic field b. charged particles ejected from the Sunc. Solar flares d. More than one of the above

____ 13. The composite tidal pull of the Sun and Moon is greatest when __. a. Earth, Sun, and the Moon are at the vertices of an equilateral triangle b. Earth, Sun, and the Moon all lie along the same straight line c. Earth, Sun, and the Moon are at the vertices of a right triangle d. This question is irrelevant; the composite tidal pull of the Sun and the Moon never

vary

____ 14. The greenhouse effect __. a. increases a planet’s surface temperature b. reduces a planet’s surface temperature c. increases the radiation that reaches a planet’s surface from the Sun. d. keeps heat energy from reaching a planet’s surface

____ 15. Which of the following is the correct order of layers (from innermost to outer) of the Earth? a. core, mantle, crust c. core, crust, mantle b. mantle, core, crust d. mantle, crust, core

____ 16. In order for a planet to have a magnetic field, we believe that the planet must have __. a. a molten (liquid) core b. a core made from material that conducts electricity c. a core that is rotating d. all of the above are believed necessary

____ 17. The magnetic field around Earth is called __. a. the aurora borealis c. the magnetosphere b. the upper atmosphere d. a force line

____ 18. Which of the following processes affect(s) the Earth surface? a. impact cratering c. erosionb. volcanism d. all the above

____ 19. The rotation of the Earth is ___. a. speeding up as the Moon moves closer to the Earth b. speeding up as the Moon moves further from the Earth c. slowing down as the Moon moves closer to the Earth d. slowing down as the Moon moves further from the Earth

____ 20. Oxygen in the Earth’s atmosphere was primarily __. a. outgassing from volcanoes on Earth b. trapped in the Earth’s crust inside rocks c. created by plants on the Earth’s surface d. locked inside the Earth’s atmosphere by the Sun

Earth-Moon System: Earth’s Orbital Motion Day 2 Planet Earth: Earth’s Orbital Motion

Rotation - Spinning of Earth on its axis - 1 Rotation = 1 Day - Celestial sphere does not move - Earth rotates inside the celestial sphere

Revolution - Earth orbits around the sun - 1 Revolution = 1 Year

Diurnal Motion - Right Ascension and Declination of objects don’t change - The observer “sees” the stars move the same way every day - Observers from different latitudes see different motion - This motion is due to Earth’s rotation

A View From The North - North Celestial pole is directly overhead - Stars move around the north star

View From The Equator - Celestial equator is directly over the equator – thus directly overhead

Mid-Latitudes - Neither celestial pole or the celestial equator are directly overhead - Stars rotate around the north celestial pole

Planet Earth: Annual Motion Annual Motion - Sky appears to change due to earth’s revolution - Follows a yearly cycle - Responsible for seasons

Seasonal Changes - Because of this change the sun appears to move relative to the background stars Ecliptic - The apparent path of the Sun, relative to the stars on the celestial sphere, over the course of a year - The Sun, Planets, and Moon are found near the Ecliptic

Plane of Ecliptic - Plane = Plane of Earth’s orbit around the sun - Inclined 23.5o to celestial equator - Tilt = Tilt of Earth’s axis

Time - Is measured by the sun - A day is one rotation of the Earth

Solar Day - A solar day is one rotation of the Earth measured by the position of the sun - Period of time from noon one day to noon the next day - Is our basic social time unit

Sidereal Day - Time required for Earth to rotate exactly once, relative to the stars - Differs from Solar Day Solar vs. Sidereal Day - Results in Earth’s simultaneous rotating & revolving - Solar day 3.9 minutes longer than Sidereal Day

A.M. and P.M. - At midday, the Sun is on your meridian

- This occurs close to, or at, noon - A.M. comes from ante meridiem (before midday) - P.M. comes from post meridiem (after midday)

Apparent Solar Time - Is the time measured with respect to the actual position of the Sun

- At noon, the Sun would be exactly on the meridian - 1 P.M. would be exactly one hour after the Sun was on the meridian. - 9 A.M. would be exactly 3 hours before the Sun was on the meridian

- Depends on your longitude

Apparent Solar Time - The length of an apparent solar day varies throughout the year

- Although the rotation of Earth is fairly constant, the revolution speed of Earth in orbit around the Sun is not. - Kepler’s Second Law - Earth moves faster when it is close to the Sun and slower when it is further from the Sun - In one day in January, Earth must rotate a little bit more than one day in July in order to bring the Sun back to the meridian because Earth has moved further in its orbit during that one day.

Sidereal Time Mean Solar Time - Therefore, the length of an apparent solar day is variable. - Rather than constantly resetting our watches as the length of the solar day varies, we keep using mean solar time.

- A mean solar day is the average length of a solar day during the year. - Mean solar time is the time kept by a fictitious “Sun” moving at a uniform rate along the equator

- A sundial keeps apparent solar time and it will differ from the time on your watch during the course of a year.

- This means that the true Sun is not always on the meridian at exactly noon. - Sometimes the sun is on the meridian before noon and sometimes after noon. - The difference, called the equation of time, can be as much as 17 minutes.

Apparent Solar Time - The path of the Sun at noon during the year makes a figure 8 shape called the analemma.

- The north-south motion is due to the 23.5 degrees tilt of the celestial sphere with respect to the ecliptic. - The east-west motion is primarily caused by the varying speed of Earth in its orbit around the Sun.

Analemma

Shifting Celestial Sphere - Each night, the whole celestial sphere appears to shift a little compared with the night before

Annual Motion - Because Earth revolves around the Sun, the night sky changes 1o each night

A Complication - The Earth’s Revolution Axis is not aligned with its Rotation Axis - Difference in the tilts is 23.5 degrees A Consequence

- Because of this tilt difference, the declination of the Sun changes from -23.5° to +23.5 °

Seasons - Caused by changes in Sun’s declination

Planet Earth: Four Seasons Summer Solstice - Sun at northern-most point above the celestial equator - North Pole closest to sun - ~ June 21st - 1st day of Summer - Days longer than nights in Northern Hemisphere - Sun’s rays more directly on Northern Hemisphere

Winter Solstice - Sun at Southern-most point below the celestial equator - South Pole closest to sun - ~ December 21st - 1st day of Winter - Nights longer than days in Northern Hemisphere - Sun’s rays more directly on Southern Hemisphere

Vernal Equinox - Date on which the Sun crosses the celestial equator moving northward - ~ March 21st - First day of Spring

Autumnal Equinox - Date on which the Sun crosses the celestial equator moving southward - ~ September 22nd - 1st day of Fall

Northern Hemisphere - Is the Earth closer to the sun during summer or winter? - Why?

Why is it Cold During the Winter? - Sun is at a declination of -23.5° - Northern Hemisphere is tilted away from Sun - Sun’s light is spread over a larger area - Sun’s light is scattered by more of Earth’s atmosphere

Planet Earth: Other Orbital Variations Milankovitch Cycles - Periodic variations that occur due to gravitational interactions - Determine climatic patterns on Earth through orbital forcing - Involve changes in:

- Axial tilt - Precession - Earth’s orbital shape

Orbital Forcing - Effect on climate resulting from slow changes in the tilt of Earth’s axis and shape of the orbit - Changes the total amount of sunlight reaching earth by up to 25% at mid-latitudes - Believed to be responsible for the timing of the ice age cycles

Change in Axial Tilt - Axial tilt varies from 22.1° to 24.5° - Full cycle occurs roughly every 41,000 years - When obliquity increases the summers receive more insolation and winters receive less - When obliquity decreases, summers receive less insolation and winters more

Precession - Wobbling of earth on its axis - The change of Earth’s axis of rotation relative to fixed stars - Due to tidal forces exerted by the sun and moon on the Earth which have caused the earth to be an ablate spheroid rather than sphere - Cycle is roughly 26,000 years Changing Orbital Shape - Eccentricity of orbit varies from 0.005 to 0.058 with a mean eccentricity of 0.028 - Occurs on roughly a 100,000 year period - Current eccentricity is 0.017 - When orbit is at its most elliptical, the solar radiation at perihelion will be about 23% more than at aphelion - Currently the difference is only 3.4%

Name ______________________________________ Date _____________ Block ________

Earth’s Orbital Motion I. Use the words in the box to fill in the blanks in the statement. 1. A round, three dimensional object is a ______________________. 2. All points on a sphere’s surface are the same distance from the ______________________

of the sphere. 3. Images from space probes and artificial satellites show that Earth is

_____________________. 4. _______________________ is the time required for Earth to rotate exactly once relative to

the stars. 5. The North and South Poles are locates at the ends of Earth’s

__________________________, the imaginary line around which Earth spins. 6. The spinning of Earth on its axis that causes day and night is called

_______________________. 7. One complete rotation of Earth takes about _____________________________. 8. Earth’s yearly orbit around the sun is its _____________________________. 9. ______________________ is the slow change in the direction of the rotation axis of a

spinning object caused by some external influence. 10. One complete revolution of Earth takes about __________________________. 11. The path of Earth’s orbit is in the shape of an elongated closed curve called an

_________________. 12. Earth’s tilted axis causes ______________________________. 13. _______________________ is one rotation of the Earth measured by the position of the

sun. 14. During a(n) ______________________ day and night are equal. 15. During a(n) ______________________ day and night are not equal. II. Answer the following questions on the lines provided. 16. What is the sun directly over at the equinoxes? __________________________ 17. Which season begins in the northern hemisphere when the sun reaches its greatest

distance south of the equator? ________________________________ 18. On what date does the southern hemisphere begin spring?

_____________________________ 19. At March equinox, what season begins in the northern hemisphere?

_______________________________ 20. At the summer solstice in the northern hemisphere, at what point is the sun?

_______________________________ 21. The Earth’s _______________________ is an imaginary line around which Earth spins. 22. The axis is _____________________________ at an angle of about 23o. 23. This allows different parts of the Earth to receive different amounts of

_______________________. 24. When the Earth travels around the sun it is called _________________________________.

revolution ellipse seasons center sphere-shaped sphere 24 hours 365 days axis sidereal day solar day precession equinox rotation solstice

III. Label the diagram below then answer the questions that follow.

25. How long does it take for the Earth to complete its period of revolution, or one orbit around the sun? _______________________________

26. Is the Earth closer to the sun during the winter or summer in the Northern Hemisphere? __________________________

27. During which season is the Northern Hemisphere tilted toward the sun? _______________________

28. Away from the sun? ________________________ 29. Name the day during which the Northern Hemisphere has the greatest number of daylight

hours. ___________________________ 30. Name the day during which the Northern Hemisphere has the least number of daylight

hours. ___________________________ 31. When is the shape of the Earth’s orbit? __________________________ 32. When is the sunlight most concentrated on the Northern Hemisphere?

_______________________ 33. Name the day when the number of daylight hours equals the number of nighttime hours and

the sun is progressing north of the celestial equator. ____________________________ 34. The Earth’s axis is always tilted toward _______________________________ (name of

star). 35. The northern winter is cold because the sun’s light is not as

___________________________ and it has to travel through ______________________ (more, less) of Earth’s atmosphere.

Name ______________________________________ Block ________ Earth's Seasons (ID.A) True/False Indicate whether the sentence or statement is true or false.

____ 1. The vernal equinox marks the beginning of spring in the

northern hemisphere.

____ 2. At the solstices, the Sun's declination will be 23.5 degrees from the equator.

____ 3. At the equinoxes, the declination of the Sun must be zero degrees.

____ 4. When the northern hemisphere experiences summer the southern hemisphere experiences winter.

____ 5. During the equinox, the number of daytime hours is greater than the number of nighttime hours.

____ 6. The fall equinox occurs on March 21st.

Multiple Choice Identify the letter of the choice that best completes the statement or answers the question.

____ 7. What will cause Polaris to lose its place as the “North Star”?

a. Stellar parallax c. Proper Motion b. Precession d. Retrograde motion

____ 8. What is an Astronomical unit? a. The average distance between any planet and the Sun. b. The average distance between planets. c. The average distance between the Earth and the Sun. d. The wing of a hospital set aside for treating aliens.

____ 9. The average distance from the earth to the sun is a __. a. parsec c. astronomical unit b. light year d. quark

____ 10. The primary cause of the seasons is __. a. the changing distance of the Earth from the Sun b. the changing heat capacity of the ozone layer above the polar vortex c. the tilt of the Earth’s rotation axis as compared with its orbital plane d. precession

____ 11. __ is measured in reference to the position of the Sun. a. Sidereal Day b. Sidereal Year c. Solar Day d. Solstice

____ 12. __ is the slow change in the direction of the rotational axis of a spinning object caused by some external force. a. Diurnal Motion b. Precession c. Azimuth d. Zenith

____ 13. The sun is over the ___ during the summer solstice. a. equator c. Tropic of Capricorn b. Tropic of Cancer d. North Pole

Matching

Match the terms below to their correct locations in the diagram.

a. A c. C b. B d. D

____ 14. Summer Solstice

____ 15. Vernal Equinox

Match the descriptions below to the correct terms listed. Each term may be used more than once or not at all. a. Summer Solstice c. Vernal Equinox b. Winter Solstice d. Autumnal Equinox

____ 16. The 1st day of fall

____ 17. The sun is at its highest point in our Gloucester sky on this day

____ 18. Nights longer than days

____ 19. 1st day of spring

____ 20. Sun at its southern-most point below the celestial equator

Astronomy Unit 3 Packet

Documents

Transcript of Astronomy Unit 3 Packet