//p/1/./1// Flashcards
(46 cards)
1
Q
- What is the solar system?
A
-our planetary system
2
Q
- What is in our solar system?
A
Planets, moons, comets, asteroids, dwarf planets, gas, dust, our sun (a star)
3
Q
- How many planets are in our solar system?
A
8
4
Q
- What are the names of the planets in order?
A
Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune
5
Q
- What are planets in our solar system?
A
- orbit our sun
- they reflect the suns light
- terrestrial close to sun, gas giants further away
6
Q
- What are moons in our solar system?
A
- smaller lumps of rock
- orbit planets
7
Q
- What is the sun in our solar system?
A
- a star
- large
8
Q
- What are asteroids?
A
- a rocky irregular body
- orbit the sun in elongated (eccentric) ellipses
9
Q
- What is a dwarf planet?
A
- small planets that haven’t cleared their orbit
- e.g. Pluto
10
Q
- What are comets?
A
- a comet is a ball of rock, dust and ice
- orbits the sun in an elongated ellipsis
- tail is formed when ice melts near sun
11
Q
- When was the solar system formed? Why do we think this?
A
- 5000 million years ago
- solar system must be older than oldest rocks
12
Q
- How was the solar system formed?
A
- cloud of gas and dust disturbed (maybe by a supernova explosion)
- explosion= waves= squeezed cloud= collapsed and span
- hot and dense in centre= protostar
- when hot enough= fusion= sun
- outer disked formed clumps= planets and moons
13
Q
- What is the sun?
A
The sun is a star, one of the thousands of millions of stars in the Milky Way
14
Q
- What makes up the universe?
A
-thousands of millions of galaxies containing thousands of millions of stars
15
Q
- Order by size the diameter of the earth, the sun, the earth’s orbit, the solar system, the milky way, the distance from the sun to the nearest star and the distance from the milky way to the nearest galaxy: (smallest to largest)
A
Smallest to largest:
- Diameter of the Earth
- Diameter of the Sun
- Diameter of the Earth’s orbit
- Diameter of the Solar System
- Distance from the Sun to the nearest star
- Diameter of the Milky Way
- Distance from the Milky Way to the nearest galaxy
16
Q
- How do astronomers gather information about distant stars and galaxies?
A
-from the radiation they can detect
17
Q
- At what speed does light travel through space (a vacuum)?
A
-a very high but finite speed, 300,000 km/s
18
Q
- What is a light year?
A
-the distance travelled by light in a year
19
Q
- Why do we observe distant objects as they were in the past?
A
-because distant objects are so far away it takes a long time for the light to reach us to see the distant objects as they were when the light left them
20
Q
- What is parallax used to measure?
A
Nearby stars
21
Q
- Why can’t parallax be used for further stars?
A
Because the parallax angle will be too small, and telescopes on earth are not accurate enough as the Earth’s atmosphere distorts them
22
Q
- What is parallax?
A
Parallax is the apparent movement of an object when you look at it from different places
23
Q
- How can the distance of a star be measured using parallax?
A
A nearby star will appear to move against a background of more distant stars. An astronomer will measure a stars position 6 months apart to calculate the apparent change. The angle is HALF the apparent change
24
Q
- How is parallax angle calculated?
A
d=1/p
d= distance (parsecs)
p=parallax angle (arcseconds)
25
11. What are the units of distance when measuring parallax angle?
-parsecs
26
11. What units is parallax angle measured in?
-arcseconds
27
12. How can the distance to a star be estimated?
-from its relative brightness
28
12. How can the distance to a star be estimated from its relative brightness?
-the brighter the star the closer it is
| they take into consideration how much radiation that type of star actually emits
29
12. What are the problems with using relative brightness to measure the distance of stars?
- star could be close but not bright
| - star could be far away but bright
30
13. What can interfere with observations of the night sky? Why?
- light pollution: hard to see dim objects
| - other atmospheric conditions: absorbs light before it can reach us
31
14. Why are there uncertainties about the distances of stars and galaxies?
- because it is difficult to make observations
| - assumptions must be made when interpreting observations
32
15. What is the source of the suns energy?
-the fusion of hydrogen nuclei
33
15. How does fusion in the Sun occur?
- when lighter elements (nuclei) are forced together (overcoming repulsion) to become heavier elements (nuclei)
34
16. Where are all atoms heavier than helium made and how/why?
In stars, with heavier elements fusing together
35
17. What is redshift?
-redshift is when the wavelength emitted from an object (of visible light) is stretched towards the red end of the spectrum (infrared), which shows it is moving away from us.
36
17. What does red shift tell us about the movement of galaxies?
- that they are moving away from us
| - because if they are red shifted it shows the stretched wavelength which shows they are moving away from us
37
18. What happens to the motion of the galaxy the further it is away from us?
-the further away the galaxy is from us (generally), the more red shifted it is so the faster it is moving away from us. This is shown by Hubble expansion.
38
19. How do the motions of the galaxies suggest the universe is expanding?
-because if all the galaxies are moving away from each other, this means that the universe is expanding (at an increasing rate)
39
20. What are the relative ages of the Earth, the Sun, and the Universe?
- Earth: 5000 million years
- Sun: 5000 million years
- Universe: 14000 million years
40
21. How do scientists believe the Universe began?
-with a ‘big bang’
41
21. What is the Big Bang theory?
- all the matter and energy was compressed into a very small space
- something caused it to start expanding, it is still expanding now
42
21. How long ago do scientists think the Universe was formed?
-about 14 thousand million years ago
43
21. How did scientists predict how long ago the Universe was formed?
-age of Universe is estimated by current rate of expansion
44
22. Do we know the ultimate fate of the Universe? How can we determine it?
-we don’t, it depends on the speed of expansion and mass
45
22. What are the options for the fate of the Universe?
- if enough mass compared to speed= stop expanding= contract= big crunch
- if not enough mass= expand forever
46
22. Why is the ultimate fate of the Universe difficult to predict?
- to calculate speed you would need to calculate large distances
- difficult to accurately measure distances
- have to make assumptions about objects motions
- pollution gets in the way
- most mass is dark matter so hard to measure mass
