Astronomy

Front 1

What is the criteria for a planet?

Back 1

1) Must have enough gravity to form a sphere
2) Must orbit the Sun (or star)
3) Must be dominant object in part of solar system. If smaller objects, must be satellites. Able to clear out with its gravity.

Believed to be designed to exclude Pluto.

Front 2

Who is responsible of demoting Pluto?

Back 2

Percival Lowell
Clyde Tombaugh

Front 3

Asteroid

Back 3

Aster in greek means star "disaster".
Oid means looks like but really doesn't.

-Any of numerous small celestial bodies composed of rock and metal that move around the sun (mainly between the orbits of Mars and Jupiter)

Front 4

First 4 Asteroids to be discovered

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-Ceres (first discovered. largest, but would fit in TX.)
-Pallas
-Juno
-Vesta

Founded in 1807 by Gillseppe Piazzi and Georg Bessell

Got their names by Herschel.

Front 5

How were Asteroids found?

Back 5

Most discovered by accident. Asteroids found b/c they are blurs in photos. They move independently.

Map out thousans of Asteroids orbit by using the law of gravity.

Front 6

James Bond

Back 6

the 10,007 Asteroid mapped out.

Front 7

Symbolic delivery

Back 7

Some symbol of the gift, a letter, etc.

Front 8

Amor Asteroids

Back 8

Asteroids that are taken out of the belt for a brief time. They have orbits that are so noncircular that they get closer to the sun than Mars! Almost a threat to Mars, close encounters. Explaining Mars 2 satellites Phobos and Diebos being asteroids.

Front 9

3 things that can happen with an Asteroid

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1) Collide
2) Orbit (rarest possibility)
3) Fall toward planet and miss b/c too fast or wrong angle.

Front 10

Apollo Asteroids

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Have a highly elongated orbit. They spend most of their time in the belt, but for a brief moment they are closer to the sun than the Earth is.

"Earth crossing Asteroids"
Icarus- get closer to Sun crosses orbit w/Earth
Opophus- destroys world in a myth.

Front 11

Ways to defeat an Asteroid

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Best bet is to change orbit.

1) A nuclear weapon to nudge into a new orbit.
2) Tow asteroid w/space ship.
3) Use light from rays of Sun.

Do have technology to defeat an Asteroid.

Front 12

Trojan Asteroids

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Share an orbit w/Jupiter. Same distance and same time to orbit around Sun as Jupiter. Split in 2 groups, named after Trojan war.

Eastern = 60 degrees ahead of Jupiter
Western = 60 degrees behing Jupiter

Held in placeby competing gravity by Jupiter and the Sun.

Front 13

Lagrangian Points

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L4 & L5 points most stable. GRAVITATIONAL BALANCE POINTS!

If an object (like Trojan asteroids) are in this point they are held in place by Jupiter and the Sun.

Front 14

What are Asteroids?

Back 14

Represent the building blocks of a planet that never had a chance to come together. Planets from asteroids.

Front 15

COMETS

Back 15

Similar to asteroids but different in composition."fuzzy"

Brahe tested in 1500s;
When looking at a cloud, different perception no matter location.
When looking at a moon everyone looks at same point.
--No matter Brahe observed comet it was in the same place. Out among planets and not in our atmosphere.

Front 16

Edmond Halley
"Halleys comet"

Back 16

went through historical records. Fund records of exact dates of when comet seen and when it dissapeared. Many happened 75 years apart. Reconstructed the orbit of Halleys comet. Died before ever getting to see it.

Front 17

Orbit of Halleys Comet

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@ Perihelion point very close to the Sun
@ Aphelion close to Neptune.

Orbit is tilted by 18 degrees compared to planets. Similar to Pluto. Does not follow plane of the solar system.

Front 18

"Dirty Snowball" Theory

Back 18

Fred Whipple tried explaining Comets by saying that most of the time a Comet is an irregularly shaped rock and ice a dozen miles across. Spend most of their time very far away from the Sun and outside of the solar system. When it gets close to the Sun it melts and evaporates slowly.

Front 19

Coma

Back 19

A cloud of vapor around the Comet made up of gases evaporated by Nucleus. The gas of the nucleus depends on the nucleus. CO2, H2O, Methane.. As it gets warmer that sphere of gas expands. Coma 1,000 miles across at max size. Density of gases in coma are low. We can not even produce gas that thin.

Less than a 1% of ice melts on a comet and becomes the Coma, very low density but yet massive.

Front 20

How do we see a Coma? (A comet go by in the sky at night?)

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Sunlight is passing through the Coma and as the sunlight passes through it energizes those gases enough to absorb a small portion of sunlight hold onto it for a millisecond and then spit it back out in all directions. Coma is literally glowing like a flourescent light. Not reflecting, rather collecting.

Some atoms absorb too much light and some electrons and some become ionized. When gets closer to the Sun becomes more ionized. More Ions appear so comet gets a halo all around the comet. A halo consisting of one or more Plasma (positive electricly charged Ions). Sun gives off solar wind as well as sun light. Solar winds made up of negatively charged particles (electrons). Opposites attract!! Solar wind sweep over comet. Electrons grab ions in halo and carry them away from the comet Creating a TAIL!

Front 21

Ion Tail (Type I)

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When closer to the sun more of a tail! Can stretch 100 million miles away from the comet. Gases in tail are very thin.

Front 22

Dust Tail (Type II)

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Dust in comet not just ice. The rock and dust are blown away solar wind creating the dust tail. Instead of being blown away it lingers in the comet.

Front 23

What direction does a comets tail point?

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Always away from the Sun, not behind the Comet. Caused by the solar wind not motion. Tail independent. (Like walking in the wind and your hair blowing)

Front 24

Long period comet VS Short period comets

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Long period goes far beyond our solar system. The Oort cloud helps explain these.

Unlike, Halleys comet a short period that stays within our solar system.
-Replenished by starting off like a long period comet. During a trip encounters Jupiter and the gravity alters orbit of comet. Causing it to come into a smaller orbit. Pulls hard enough to change the orbit!

Front 25

Jan Oort

Back 25

Proposed a structure that he called the comet cloud. A spherical shell eventually being called the Oort Cloud made up of dust bunnys surrounding the solar system.

Front 26

The Oort Cloud

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Hypothetical theory! Used for explaining long period comets. Other stars influence this because it is so far away. Disturbance is able to shake loose some comets. Some go into outer space and others fall in towards the Sun, miss, then orbit.

Front 27

Kuiper Belt

Back 27

Proposed by Gerard Kuiper.
Comet belt out beyond Neptune (like asteroid belt) chunks of rock and ice. Gravity of Uranus or Neptune disturbs orbit causing it to fall into Sun.

Front 28

METEORS

Back 28

A chunk of material floating in space. Smaller than a planet. Usually rock, metal, or ice.Travels faster than 7 miles per second. Do encounter friction and does slow them down a bit or most meteors dissolve.

When captured by gravity from a larger object and starts falling toward object than becomes a Meteor.

Front 29

Shooting Stars

Back 29

A meteor that slows down a bit and the air heats up alot causing a streak.

Meteor showers.
1) too small to impact
2) all come from the same place
3) very predictable. happen the same time every year.
Meteor and meteor showers are dust left behind by a comet
4) small group that comes from other planets caused by crazy impacts

Front 30

Meteorite

Back 30

If a meteor reaches Earth and someone picks it up it is called a meteorite. Made up of 7% Fe, 92% rock, and 1% 50/50 mixture of both.

Front 31

Difference between Meteorites and Earth Rocks

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Meteorites have a higher abundance of Au, Pl. All high in density.

Front 32

Where do Metorites come from?

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1) Space left overs of material from the creation of the Solar System.
2) Asteroid belt (collisions with only Fe core)
3) Meteor showers (shooting stars)

Front 33

Planetesimals

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Any of innumerable small bodies thought to have orbited the sun during the formation of the planets.

Front 34

Roche Limit

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Tears apart anything that gets to big that gets too close to the planet or Sun.
--Distance at which tidal forces becomes stronger than gravity force holding you together.

Accreation is limited inside the Roche limit.

Front 35

Accreation

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Brings materials together.
-the process of growth or enlargement by a gradual buildup

Limited inside the Roche limit.

Front 36

Condensation Theory

Back 36

Evolutionary Theory that is a slow gradual process.

-Planets form by product from Stars. If you form a star, planets will follow.

Front 37

Catastrophies

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1) Venus spinning backwards.
2) Thin atmosphere on Mars.
3) Uranus and every moon and rings tilted at 98 degrees.
4) even our Moon, Luna. (only Moon in inner planets)

Front 38

How did we get our Moon?

Back 38

Formed without Moon. Earth struck by a large Planetesimial or a side swipe that barely grazed Earth. As result, intruder destroyed along with large part of Earth. Flew off into space, formed by process of Accreation.

Front 39

Rene Descartes

Back 39

French philosopher. Most famous for philosophical “I think, therefore I am”. X and Y coordinates, married Algebra and Geometry which is now College Algebra.

Created the Nebular Hypothesis.

Front 40

Nebular Hypothesis

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(example of evolutionary hypothesis)- The Sun and by extension the Solar System formed out of a cloud of gas collapsing under the influence of gravity. Our solar system was formed as a biproduct of the Sun, they formed together.

Front 41

Pierre Simon de la Place

Back 41

expanded on Descartes work. Said the Solar System did indeed form out of a gas collapsing under the influence of gravity. This cloud of gas and dust was initially spinning counter clockwise. When gravity takes hold of it and causes it to shrink, as the cloud shrinks, its radius and volume decreases. Material rushes inward towards to center of the cloud (solar nebula), and as that happens the cloud spins faster. The more it collapses the faster it spins.

Front 42

Pros and Cons of Nebular Hypothesis

Back 42

Pros:
-Poles are collapsing faster than the equator, which turns the sphere into a disc.
-Also explains why the solar system is so flat!
-Bc planets formed out of a flat disc and so the planets conformed to the disc.

Cons:
-does not explain the difference between the inner and outer planets. (forgiven bc did not know about the inner and outer planets)
-“La Place says the sun forms out of most of the material in the disc and the rest of the material forms the planets.” Never said how the planets were going to form out of the cloud of gas. How did the gas clump together in planets? How to get gas to go against its natural tendency?
-**The Sun went from a nebula to an object that is only a million miles across. Very radical change. Yet, the sun only spins once every 25 days. Should be fastest spinning object in solar system. How is it still spinning so slowly?

Front 43

Collision Hypothesis (catastrophic hypothesis)

Back 43

proposed by Georges de Buffon.
-The sun formed without planets, so no need to spin so fast that you turn into a disc. Spinning very slowly. Another star came by and got really close to Sun, so close they drew material off each other. Forming a bridge between them. Didn’t last long, bridge broke and material fell off onto most of both stars, the rest of the material started to orbit the Sun and became the planets.

Front 44

Problems with Collision Hypothesis

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1) extremely unlikely to occur, bc space is big. A star like the sun might be a million miles across, but separated by millions and millions of miles. A random encounter between two stars is so rare as to be virtually impossible. (Although does happen but in those cases the stars are born that close together, form a binary system)
2) Probably wouldn’t work bc gas disburse very unlikely to gather in clumps.
3) The planets just don’t look like material ripped from the surface of the Sun. Even Jupiter which is closest to the Sun, has important differences. Enough similarities to believe we all formed out of the same cloud, but enough differences to not believe we were made from the Sun.

Front 45

Two Hypothesis groups represent two different origin

Back 45

**To say something it is an evolutionary process is merely to say its process is slow gradual change.
**To say something is an catastrophic hypothesis is to say that it all came from one major single violent event.

Front 46

Things that saved the Nebula Hypothesis

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-We discovered there is quite a lot of dust (little rock and metal) in our galaxy. The presence of dust helps us to solve the problem of how things got clumped together. How the gases came to clump together. Dust grains help the gases assemble into clumps. Instead of disbursing which is what gases do on their own.

Front 47

Condensation Theory
(The Modern Theory)

Back 47

relies on large amounts of dust to gather the gases in the nebula to make everything in our solar system.

When the Sun is first born it is spinning rapidly with a crazy strong magnetic field, surrounded in disc of loose material (gas and dust). A lot of the material in the disc has an electric charge (ionized gases, electrons). That means, that the magnetic field of the Sun can push it around. Starts to push and pull on the material in the disc.

Front 48

Magnetic Braking

Back 48

slows down the sun to its current slow rate of spin. Phenomenon.

Front 49

How the Solar system was made?

Back 49

-Solar system formed out of a large cloud of gas and dust. The cloud was 99% gas (H, He, C, N, O) Variations of these 5 materials. 5 most common material in the universe in this order. 5 lightest and simplest materials in universe. Think of these materials as Volatile materials. Easily melted and easily evaporated. Gases and liquid state on Earth.

-The remaining 1% is made up of dust (Si, Ca, S, Fe, Ni)”rock and metal”.. heavier atoms, more complicated, higher density materials. Rare in this universe. Refractory materials. Difficult to melt and difficult to evaporate. Solid State on Earth.

Initially solar nebula was a sphere but as it got smaller and smaller it spun faster. This rapid spin caused it to flatten out into a disc. Most of the material 99.9% rushed inward, causing it to become very hot and very dense until it met the ideal temperature to start nuclear fusion. Center form of disc became a star. Newborn Sun had a dramatic effect on the portions surrounding it. Magnetic field churned up the materials in disc causing it to spin even faster. Angular momentum was transferred out from the Sun into a disc, soon shared by all of the planets. The Sun also produced a lot of heat when it first flared up, it melted and evaporated the Volatile materials in the inner parts of the disc, outer parts still solid. Just warmed the Refractory. The Sun also produces a fierce Solar Wind, electrically charged particles stream out in a strong solar wind. SOLAR WIND HELPS EXPLAIN THE DIFFERENCES BETWEEN INNER AND OUTER PLANETS.

The inner planets are left with 1% to make planets out of. Made of rock and metal bc that’s all that was left after the Solar wind blew everything away. Why they are so small and no moons or rings.

The outer planets are bigger bc they were built with the original 99% material and also built from the material the solar wind blew away. So many extras? So much material to work with.