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Flashcards in Space Deck (33):
1

What is a light year?

The distance that light travels in 1 year (9.26 x 10^12)

2

What is an astronomical unit?

The distance from the Earth to the sun (1.5 x 10^8)

3

Which direction does the Earth rotate?

West to East

4

What are the 4 reasons that Earth is so perfect for life?

1. Distance - not too hot, not too cold
2. Magnetic field (magnetosphere) - stops solar wind from stripping atmosphere
3. Tilt - heat is distributed regularly over Earth
4. Atmosphere - traps heat from sun to create new greenhouse effect

5

How old is the milky way?

8-9 billion years

6

How long did it take for H and He to form?

377 000 years (after temperature cooled)

7

How hot was it, during the Big Bang?

10 billion K

8

How old is the universe believed to be? How do we know?

12.7 billion years old, and we know the rate of expansion

9

How do we know the universe is expanding?

1. Galaxies appear to be moving away from us (Doppler effect)
2. Remnant cosmic microwave background = radiation left over from the big bang, used to be gamma rays, now is microwave

10

How can we tell the latitude?

Fist = 10 degrees
Telephone = 20
Three fingers = 5
Pinky = 1

11

What are nebulas?

Star-forming clouds of dust (irregular grains or carbon & silicon) and gas

12

What is a protoplanetary disk?

Disk of gas & planetismals, forms along equatorial region

13

What is the nearest star forming region?

The Arion Nebula

14

How was our solar system formed?

1. Gravity pulls clouds of dust t/g
2. H begin gathering, as they become more concentrated = protostar
3. Powered by nuclear energy, they push aside the dust of their cocoons
4. Surrounding these new stars are left over material
5. Gravity + rotation causes dust to form flat disks which will eventually form planets

15

How are stars made?

- cloud of hydrogen gas
- balls of gas formed
- balls of gas expanded

16

How do stars die?

- stars run out of hydrogen fuel
- star cools, shrinks, collapses under weight
- star crashes inward and explodes!
- supernova creates new worlds

17

What is a lunar eclipse?

When the full moon passes into Earth's shadow. You can see it anyway & it is safe to watch

18

What is a solar eclipse?

When the shadow of the new moon falls on Earth's surface. You must be in a specific place but not safe to watch

19

Why don't we have a lunar eclipse every full moon?

The orbit of the moon is tilted 5 degrees to Earth's orbit about the sun. The full moon usually passes above or below Earth's shadow

20

On the equinoxes, all places on Earth experience equal hours because __________

During those dates, the earth is not tilted towards or away from the sun

21

What is the oort cloud?

Sphere of small, icy debris at the farthest reaches of the sun's gravitational pull

22

How are tides caused?

By the difference between the force of gravity on 1 side of the Earth nearest the moon and the side farthest

23

What are the 3 pieces of evidence supporting the solar nebula theory?

1. Cratered surfaces of moon +mercury (pounding of nebula?)
2. Planets revolve around sun in 1 direction (nebula spins in 1 direction)
3. LOTS of planets (planets are by-products of stars)

24

What is the nuclear fusion process?

1. Nuclear fusion starts when star gets hot enough (you need it to be highly pressurized)
2. Hydrogen nuclei combine to form helium nuclei
3. Protostar begins to consume fuel (core heats up which increases pressure)
4. Pressure and gravity balance out, creating a star!
5. Star continues to fuse H and He, so core grows bigger and bigger

25

What are sunspots?

Area of strong magnetic field on photosphere

26

What are solar flares?

Complex groups of sunspots. Causes solar wind

27

What is solar wind?

Explosively ejected streams of charged particles into space

28

How is the Auroras an example of solar wind?

Auroras result when solar wind are carried past Earth's magnetic field, generating electric currents that flow towards poles

29

How are galaxies formed?

1. Bodies of gas, dust, and protostars collide
2. Begin rotating around center of mass
3. Rotation contracts cloud to form a disk

30

Does a star's apparent brightness depend on just it's distance from Earth?

No, a star's brightness also depends on it's luminosity; a bright star is not necessarily closer to Earth.

31

List 4 properties of stars

Brightness, colour, temperature, composition

32

What is the fate of our Sun?

To become a red giant and explode in a supernova

33

How are humans stardust?

Heavier elements released through supernova explosions are ejected throughout the universe; eventually showing up on stars, planets, and HuMaNs