The Universe

Cosmology

• the branch of astronomy that deals with the origin, large-scale properties, and the evolution of the observable universe

The Universe

• in astronomy, the sum total of all things which can be directly observed or whose physical effects on other things can be detected

• in simpler terms, space and all the matter and energy in it

• major components:– galaxies– solar systems– planets

Can you think of something in the universe that cannot be seen, but its effects on other

things can be detected?

“Big Bang” Theory• the primeval explosion of space, time, matter and

energy that most astronomers think gave rise to the universe as we see it today.

• occurred about 13.7 billion years ago• thought to have expanded from something

smaller than the size of a spec of dust

Misconception Alert:Describing this theory as

the “Big Bang” is a misnomerbecause there really was not an explosion, just a release of

energy

Edwin Hubble

• determined that other galaxies exist, besides the Milky Way

• observed that galaxies were moving away from each other– Hubble Law – the

farther away a galaxy is, the faster it is moving away from us; supports the Big Bang Theory

Image taken from:http://apod.nasa.gov/apod/ap960217.html

Galaxy• a large assemblage of stars (and often gas and dust),

typically containing millions to hundreds of billions of member stars– Star - a large hot ball of gas which generates energy in its core

by nuclear reactions • around 100 billion in the universe• held together by the gravitational attraction of all its

member stars on one another• formed around 200 million years after the “Big Bang”• most large ones seem to have super-massive black

holes at their centers• sometimes contain very bright centers called quasars• 3 major types:

– Spiral– Elliptical – Irregular

What is the name of the galaxywe reside in?

3 Types of Galaxies

Spiralhave arms of stars, gas , and dust that curve away

from the center of the galaxy in a spiral pattern

Ex. – Milky Way

Ellipticalshaped like spheres or eggs; have

almost no dust or gas between stars; contain

old stars

Irregularfaint galaxies

without a definite shape; smaller than the other types of galaxies; contain

fewer stars

The process of galaxies colliding to create a larger galaxy is knownas “galactic cannibalism.”

Images taken from: http://school.discoveryeducation.com/schooladventures/universe/galaxytour/toknow.html

Milky Way Galaxy

• Scientists now know that black holes are  inexorably linked with galaxies, lying at their center and directly influencing how large a galaxy may grow. These aren’t your ordinary stellar variety black holes of mass couple of times that of our sun. No, these are classed as supermassive black holes and can have millions or, in some extreme cases, billion solar masses. Our own galaxy, the Milky Way is no exception.

Constellation

• a group of stars that form a pattern in the sky• stars of a constellation are often far apart from each

other, but they appear grouped together when viewed from Earth

• one of 88 sectors into which astronomers divide the sphere of the sky – named after a traditional constellation in that sector

• patterns of constellations are dynamic; therefore, the constellations of 100,000 years ago are quite different from today’s

• a part of a constellation that forms its own pattern in the sky is known as an asterism (ex. – The Big Dipper)

Why is it not possible to see all constellations at once?

Solar System

• the sun and all things orbiting around it, including the eight major planets, their satellites, and all the smaller pieces such as asteroids and comets

• formed around 4.6 billion years ago

Image taken from: http://asm.arc.nasa.gov/Gallery/images/generic/LG_Capableofeverything.jpg

What is incorrect

or misleadingabout this

visual?

Planet

• derived from a Greek word that means “wanderer”

• a major object which orbits around a star

• in our solar system, there are eight such objects which are traditionally called “planets”

Asteroids• small, solid, rocky

bodies that orbit close to the Sun

• most found between the orbits of Mars and Jupiter in the “Asteroid Belt”

• thought to be leftover material from the formation of the solar system

• range in size from 1000 km or 621 miles (Ceres) to the size of pebblesImage taken from:

http://www.windows.ucar.edu/tour/link=/our_solar_system/asteroids.html

Meteoroid, Meteor, Meteorite

• Meteoroid – solid debris from space (asteroids) that are moving towards Earth

• Meteor – a brief streak of light produced

by a small particle entering Earth’s atmosphere at high speed

– often referred to as “shooting stars” or “falling stars”

– travel at speeds between 11-72 kilometers per second (6.8 – 44.7 miles per second)

• Meteorite – a small object from outer space that passes through Earth’s atmosphere and reaches the surface

• Freehold Meteorite - MSNBC• Freehold Meteorite - USA-Tod

ay

Meteoroid (asteroid)

Meteor

Meteorite

The Earth animation

is not rotating in the correct direction;it should

be rotating from west

to east

What causes a meteor shower to occur?

Comet

• a small body of ice and dust (“dirty snowball”) that orbits the Sun

• contain a head (coma) followed by a tail(s) of gas and dust

• the tail always points away from the sun and can be millions of kilometers long (but the amount of matter it contains can be very small)

Image taken from: http://www.space.com/bestimg/index.php?guid=45b0fd31f065d&cat=bestcomet

Satellite

• an object that orbits a more massive object (i.e. – moons)

• probes we launch into orbit around the Earth are called “artificial satellites”

The Earth animation

is not rotating in the correct direction;it should

be rotating from west

to east

Telescope• a device that gathers

electromagnetic radiation• Types:

– Visible, infrared, ultraviolet – pick up visible, infrared, and ultraviolet waves• Reflecting - use mirrors that reflect the image being

viewed

• Refracting – using lenses, gathers light and focuses it near the opposite end of the tube; works like a magnifying glass

– Radio - pick up radio waves emitted from space; not effected by variables like weather or clouds

Internet Telescope

Hubble Space Telescope

• a reflecting telescope that was placed into orbit in 1990

• sends images and measurements back to Earth electronically

What is one of the mainbenefits of having the Hubble Space

Telescope in orbit, as opposed to it being here on Earth?

Image taken from: http://hubblesite.org/gallery/

Edwin Hubble at Mt. Wilson

Hubble guiding the Hooker100 inch telescope in 1923. The Hooker 100 inch telescope atop Mt. Wilson

near Pasadena, CA. It was the largest telescope in the world from 1917-1947.

Hubble’s observations at the 100 inch during the1920’s led him to the conclusion that the universe is expanding, and that an object’s recession velocityis proportional to its distance from the observer.

Hubble’s namesake

The Hubble Space Telescope's launch in 1990 sped humanity to one of its greatest advances in that journey. Hubble is a telescope that orbits Earth. Its position above the atmosphere, which distorts and blocks the light that reaches our planet, gives it a view of the universe that typically far surpasses that of ground-based telescopes. Hubble is one of NASA's most successful and long-lasting science missions. It has beamed hundreds of thousands of images back to Earth, shedding light on many of the great mysteries of astronomy. Its gaze has helped determine the age of the universe, and the identity of quasars

Hubble facts

The Hubble Telescope is roughly the size of a school bus, but still fits into the cargo bay of a space shuttle

Mission Launch: April 24, 1990 from space shuttle Discovery (STS-31) Deployment: April 25, 1990 Mission Duration: Up to 20 years Size Length: 43.5 ft (13.2 m)Weight: 24,500 lb (11,110 kg) Maximum Diameter: 14 ft (4.2 m) Cost at Launch: $1.5 billion

• Spaceflight Statistics Orbit: At an altitude of 307 nautical miles (569 km, or 353 miles), inclined 28.5 degrees to the equator (low-Earth orbit)Time to Complete One Orbit: 97 minutes Speed: 17,500 mph (28,000 kph)

A deep image of an “empty”portion of the sky with theHubble Space Telescopereveals that the universe isfilled with galaxies- many justlike our own. The lightwe see from the most distantgalaxies has traveled approx-imately 10 billion years to reach us.

Deep Hubble Space Telescope Image

Deep Hubble Space Telescope Images

http://hubblesite.org/videos/

http://tools.wmflabs.org/zoomviewer/index.php?f=Earth%27s_Location_in_the_Universe_%28JPEG%29.jpg

Astronomical Unit (AU)

• unit of distance equal to the average spacing between the Earth and the Sun

• equal to about 150 million kilometers (93 million miles)

• light takes about eight minutes to cover this distance

150 million km(93 million mi.)

The Earth animation

is not rotating in the correct direction;it should

be rotating from west

to east

Light Year

• the distance that light travels in one year in a vacuum, which is about 9.5 trillion kilometers (6 trillion miles)– The Milky Way Galaxy is about 100,000 light

years in diameter• the speed at which light travels this

distance is about 300,000 km/sec (186,000 mi/sec)

The second closest star to the Earth is a little over four light years away. How far

away (in miles) is the star?

Parsec

• unit of distance equal to about 3.26 light years (or 206,265 AU)

If one parsec equals 206, 265 AU, how many miles is it equal to?

Parallax

• the apparent shift in position of an object when viewed from different locations

• used by astronomers to measure distance

Parallax SimulationParallax Simulation – 1Parallax Simulation - 2

Find the Distance to HT Cas Using Parallax

Put your pointer finger in front of your face and begin opening and closing your eyes in an alternating manner.

What do you notice about the your finger’s position?