Grade 9 ScienceUnit 1/Chapter 10

What we know about the universe has taken us thousands of years to learn. Our scientific knowledge had been based on the work astronomers who experimented, collected evidence and found relationships.

Stars – give off light and heat and are very far away. Ex. the Sun

The sun is a star!______________________________________________________________________

Celestial Body – is a natural object out in space. Examples - planet, moon, asteroid, comet, or a star.

Planets moon asteroid comet star

(Many years ago farmers made note of the movement of these bodies and used them as their calendar. When certain stars were visible at certain times of the night, they knew it was time to plant their crops)

Motion of Celestial Bodies

1)Moon – a celestial body that orbits a planet. The earth’s Moon orbits the earth every 28 days. The Moon is our only natural satellite. The nearside hemisphere is the side of the Moon that always faces Earth. Therefore, it does not rotate. Other planets also have Moons. The amount of the Moon’s surface that is lit by the sun changes throughout the month.

2)Sun – follows the same ecliptic path through the sky every day. Nine plants along with asteroids and comets orbit the Sun. Some of those lie beyond Pluto but all are controlled by the Sun’s powerful gravity.

3)Asteriods – one of the many rocky or metal bodies in the solar system, most of which orbit the Sun between Mars and Jupiter. Not all asteroids orbit in this main belt. Other asteroids have wide elliptical orbits that cross the orbit of Earth.

Grade 9 ScienceUnit 1/Chapter 10

4)Comet – a small body made up of rocky material and ice that occur in the Kuper Belt and Oort Cloud; when a comet is bumped into the inner solar system, the Sun’s light may make the comet’s tail visible from earth. Comets orbit in a different direction than planets. Comet’s orbits can be above or below the orbit of Earth. Comet Halley is probable the most famous, it appears every 75 or 76 years and last flew past Earth in 1986.

5)Planet – a celestial body that orbits one or more stars. It is large enough that its own gravity holds it in a spherical shape and is the only body occupying it’s orbital path. Planets in our galaxy were named after Roman Gods (Mercury, Venus, mars, Jupiter and Saturn). As the planets revolve around the Sun they orbit at different rates along their ecliptic path. The planets inside the Earth’s orbit (Mercury and Venus) seem to race through the sky compared to the other planets. Most planets have at least one moon orbiting them. The four largest planets also have rings.

Grade 9 ScienceUnit 1/Chapter 10

______________________________________________________________________

Galaxy – an enormous collection of gases, dust, and billions of stars held together by gravity. There are millions of other stars in the universe.

-We live in the Milky Way Galaxy -This is the Andromeda Galaxy -These are the stars you see at night

Universe -is commonly defined as the totality of everything that exists, including all space, time, matter, energy, planets, stars, galaxies, intergalactic space, and beyond. The Universe had a beginning and it continues to expand.

Grade 9 ScienceUnit 1/Chapter 10

Constellations – a distinctive pattern in the night sky formed by a group of starts. The pattern often looks like a familiar object such as an animal. - 88 constellations have been named. Because we live in the northern hemisphere we cannot see 20 constellations that can be seen in the southern hemisphere. Examples – Ursa Major, Ursa Minor, Orion, Cassopiopea, and Leo (see page 354). There are 12 Zodiac Constellations. Which one is yours?

Orion’s Belt - Alnitak, Alnilam and Mintaka. These three prominent stars in the central regions of the constellation of Orion align to form the 'belt' of the Hunter.

Alphabetical listing of constellations

(Study all of these for a chapter test...Just kidding Do you recognize many of them?)

Andromeda Antlia Apus Aquarius

Grade 9 ScienceUnit 1/Chapter 10

Aquila Ara Aries Auriga Boötes Caelum Camelopardalis Cancer Canes Venatici Canis Major Canis Minor Capricornus Carina Cassiopeia Centaurus Cepheus Cetus Chamaeleon Circinus Columba Coma Berenices Corona Austrina Corona Borealis Corvus Crater Crux Cygnus Delphinus Dorado Draco Equuleus Eridanus Fornax Gemini Grus Hercules Horologium Hydra Hydrus Indus Lacerta Leo Leo Minor Lepus Libra Lupus Lynx Lyra Mensa Microscopium Monoceros Musca Norma Octans Ophiuchus Orion Pavo Pegasus Perseus Phoenix Pictor Pisces Piscis Austrinus Puppis Pyxis Reticulum Sagitta Sagittarius Scorpius Sculptor Scutum Serpens Sextans Taurus Telescopium Triangulum Triangulum Australe Tucana Ursa Major Ursa Minor Vela Virgo Volans Vulpecula

Asterism – is a smaller group of stars forming patterns within a constellation. It is not a constellation. The Big Dipper is one of the most famous and visible patterns in the northern sky. The Big Dipper is not a constellation but a smaller group of stars that are part of the constellation Ursa Major (Great Bear).

Grade 9 ScienceUnit 1/Chapter 10

Here are some more asterisms.

Circumpolar Constellations – a constellation that never appears to “set” or dip below the horizon. They are always above the horizon, even in the daytime.

Whether a constellation is Circumpolar for you depends on where you geographically live. For example, if you live in the northern hemisphere Ursa Major, Ursa Minor and Cassiopeia would be circumpolar constellations. If you lived in Australia they would not be.

The circumpolar stars are called that because they circle the pole, or the pole star. The point in the sky around which the dome of the sky appears to rotate is the Pole Star or Polaris in the Northern Hemisphere.

Grade 9 ScienceUnit 1/Chapter 10

These are our circumpolar Constellations.

Seasonal Constellations – because the Earth moves around the Sun every year, we see a different part of the sky every season. (See page 361).

Fall – Pegasus Winter – Orion the Hunter Spring – Leo Summer - Cygnus

______________________________________________________________

Models of the Early UniverseAs technology has improved so has our understanding the universe.

Grade 9 ScienceUnit 1/Chapter 10

Early Astronomers – built observatories to track the movement in the skies. In the 17th century the first telescope was invented and allowed people to see detail such as the craters in the Moon.

Ancient Observations – early people were very aware of daily and seasonal changes in their everyday lives. Fisherman used the stars to navigate by. Hunters watched the changing phases of the Moon (in a month) and the changing path of the Sun (in a year). Early people used this information to get ready for the seasons, animal migration, flooding rivers, and other natural phenomena.

Several sophisticated structures were built around the world to observe and track celestial movement (page 367); Cichen Itza in Mexico, Stongehenge in England, Pyramids in Egypt, and the Bighorn Medicine Wheel in Wyoming.

______________________________________________________________

Early AstronomersAristotle (383 – 322 B.C.E.) – in 350 BC he provided a scientific explanation of why the earth is round. He believed the universe was geocentric (planets revolved around the EARTH). He based his theories on observations he make. He believed that because patterns of stars in the sky did not change the Earth must be in a fixed place. If it moved he thought we would see patterns of stars change (page 368). He also believed that because of the shadow created by the Moon during an eclipse the Earth must be a sphere. (the earth cast shadows with curved edges on the Moon during an eclipse)

*Easy strategy to remember – Earth in the middle/ thought Aristotle

- Draw a large G around the circle to represent geocentric

Ptolemy – AD 150 he published a summary of all that was known about astronomy. It was used for more than 1,000 years. Ptolemy questioned Aristotle’s model because it did not explain all the observe motion of the planets. For example, Mar’s movement (over a period of weeks) is creates a loop or S shape. This is called retrograde motion.

E/A

Grade 9 ScienceUnit 1/Chapter 10

While observing Mars closely he also developed a model to the solar system to explain it. His model showed each planet attached to a crystal sphere with its centre at Earth. Ptolemy thought each planet was attached to an off centered wheel, which rotated as the sphere turned. This small wheel was called an epicycle.( a small circle, the center of which moves on the circumference of a larger circle at whose center is the earth and the circumference of which describes the orbit of one of the planets around the earth).

______________________________________________________________

Astrolabe – it was developed around the time of Ptolemy. Astronomers used them to help locate and predict the positions of the Sun, Moon and stars.

Copernicus (1473 – 1543) – lived before the telescope was invented. He observed the sky using just his eyes and suggested that the movement of celestial bodies that earlier astronomers had observed (the daily rotation of the heavens, the annual movement of the Sun through the ecliptic, and the periodic retrograde motion of the planets) could be explained in a simple model in which Earth rotated on it axis (tilted) once daily and revolved around the Sun once a year. He was very brave to suggest this because

Grade 9 ScienceUnit 1/Chapter 10

people in his time period believed in the geocentric model. ** Copernicus’ model of heliocentric universe set the stage for other scientists to better understand the universe and to propose their own theories based on his model.

Is this a geocentric or heliocentric model? Should you put G or H through the circle?

Retrograde Motion – it is the switch in motion of a celestial body form eastward to westward (or the other) as viewed from Earth. For example, the S shape motion seen by Mars.

Mars - retrograde motion

Galielo (1564-1642) – in 1609 he built a telescope based on another model built in 1608. He was the first person to report his use of the telescope for astronomical use. His telescope was not very strong (it only magnified objects 20 times closer) but it as powerful enough to let him see a few celestial bodies (Moon, spots on the Sun and four moons orbiting Jupiter) He figured out that Venus had phases like our Moon (then it must orbit the Sun) and therefore our universe was a heliocentric universe. Galileo published his findings. The Catholic Church (Italy) believed in a geocentric universe and put Galileo on trial for his theory. He was found guilty and imprisoned for the rest of his life.

Sun/C

Grade 9 ScienceUnit 1/Chapter 10

G *Draw a large H through the circle to represent

heliocentric

Geocentric Universe – believed the EARTH was the center

Heliocentric Universe – belief that the SUN was the centre of the universe. This theory was proposed by Aristarchus and later strongly supported by Aristotle.

Telescope – is an optical (sense of sight) device that uses lenses to gather and focus light to provide a magnified view. The satellites orbiting through space are large telescopes.

______________________________________________________________

Kepler – published his 3 laws of planetary motion. Knew about Copernican’s model and felt he could describe the motions of the planets more accurately and learn more about the solar system by using new technologies to make very accurate observations then analyze the date using math.

Sun/G

Grade 9 ScienceUnit 1/Chapter 10

Newton – in 1687 he linked astronomy with physics. Newton was considered to be the most influential scientist who ever lived. He describe 3 laws to describe and predict motion, and explain how celestial bodies move through the universe. Newton was the first to show mathematically that the force of gravity extend outside of the earth (think of the visual of Newton sitting under a tree and apple hits him on the head because of gravity). He use math to show the celestial bodies remain in orbit around larger bodies because of gravity. The Moon revolves around planets and planets revolve around the Sun in elliptical orbits. Using Newton’s laws, scientists calculate how to send people to the Moon and spacecrafts into space. He also invented the reflecting telescope that was larger and allowed more precise observations. Newton’s design for this telescope it called the Newtonian design.

The Scale of the Solar SystemMany scientists have contributed to our understanding of the universe. The basic model that we now use has not changed since Newton’s time. But astronomers have learned more about the planets and their orbits. We now know…

1. Celestial bodies in the solar system orbit the Sun in elliptical orbits (oval, egg shaped)

2. Celestial bodies are held in place by _ _ _ _ _ _ _ (I’m not tell you anymore)

Grade 9 ScienceUnit 1/Chapter 10

3. planet rotate on their axis which cause day and night (side facing sun is day)

The Scale

Planets see with the naked eye – Mercury, Venus, Mars, Jupiter and Saturn

Barely visible – Uranus (is very far away and appears to move slowly, some astronomers thought it was a star)

Cannot be seen with the naked eye – Nepturn (interesting fact – Neptune affects the gravitation orbit of Uranus. It causes Uranus to have an imperfect eclipse). Because of this scientists used math to calculate the Neptune even exists.

V –MVMJS (Can you think of a phrase to remember these letters?)

V – U

NV - N