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PHYS 284 - Astronomy > Lesson 1 > Flashcards

Lesson 1 Flashcards

1
Q

Solar system

A

consists of the Sun, the planets and their moons, and countless smaller objects that include rocky asteroids and icy comets

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2
Q

Galaxy

A

a great island of stars in space, all held together by gravity and orbiting a common center
with a common mass equivalent to millions, billions or trillions of stars

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3
Q

Galaxy clusters

A

groups of galaxies with more large members

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4
Q

Local Group

A

Milky Way and more than 70 other smaller galaxies

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5
Q

Superclusters

A

gigantic region of space in which many groups and clusters of galaxies are packed more closely together than elsewhere in the universe

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6
Q

Universe

A

the sum total of all matter and energy, encompassing the superclusters and voids and everything within them

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7
Q

What unit of measurement is used with our solar system?

A

1 astronomical unit (AU) = 150 million Km (used for within our solar system)

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8
Q

What unit of measurement is used for distances between starts and galaxies?

A

1 light year (ly) = 10 trillion Km; distance that light can travel in 1 year (used for distance b/w stars and galaxies)

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9
Q

Star

A

large glowing ball of gas that generates heat and light through nuclear fusion in its core

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10
Q

Planet

A

1) orbits star
2) large enough for own gravity to make it round
3) has cleared most other objects from its orbital path

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11
Q

Dwarf planet

A

1) orbits star
2) large enough for own gravity to make it round

BUT HAS NOT:
3) cleared most other objects from its orbital path

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12
Q

Moon (satellite)

A

object that orbits a planet; satellite is just an object orbiting another object

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13
Q

Asteroid

A

small rocky object orbiting a star

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14
Q

Comet

A

small ice-rich object orbiting star

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15
Q

Small solar system body

A

asteroid, comet or other object that orbits a star but is too small to qualify as planet or dwarf planet

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16
Q

Star system

A

a star (or multiple stars) and any planets and other materials that orbit it

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17
Q

Observable universe

A

portion of entire universe that can be seen from Earth

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18
Q

avg. distance between Earth and sun & length of semi major axis of Earth’s orbit

A

1 AU or 150 million Km

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19
Q

Light year

A

distance light can travel in 1 year = 9.46 trillion Km

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20
Q

Rotation

A

spinning of an object around it’s axis

21
Q

Orbit (revolution)

A

orbital motion of one object around another due to gravity

22
Q

Expansion of the universe

A

increase in average distance between galaxies as time progresses

23
Q

How “old” is the universe to us?

A

Earth 14billion years; distance of 14 billion ly marks the boundary of our observable universe This doesn’t mean that the entire universe is 14 billion years old; it’s just that anything further hasn’t had time to reach us yet

24
Q

How long ago did our solar system and planet form?

A

~ 4.5 billion years ago

25
Q

How long ago did dinosaurs die?

A

~65 million years ago

26
Q

How long ago did hominids begin walking upright?

A

~ 60 million years ago

27
Q

Describe earth’s rotation

A

West –> East

Rotates once each day about it’s axis at a speed of 1000km/hour

28
Q

At what degree is Earth title?

A

23.5 degrees

29
Q

How long does it take light from the moon and the sun to reach Earth?

A
  • Moon to Earth: 1 second

- Sun to Earth: 8 minutes

30
Q

How far away is the Andromeda galaxy?

A

2.5 million LY

31
Q

Name the planets in our solar system from closest to furthest from the sun

A
  • Mercury
  • Venus
  • Earth
  • Mars
  • Jupiter
  • Saturn
  • Uranus
  • Neptune
32
Q

What is the closest star to our solar system?

A
  • Star system Alpha Centauri at 4.4 ly
33
Q

Explain how a star is born

A
  • gravity compresses material in a cloud to a point where the centre is dense enough and hot enough to generate energy by nuclear fusion
34
Q

Supernovae

A

Massive star dying, blowing much of it’s content back out into space

35
Q

Describe the cosmic calendar

A
  • Compress 14 billion years onto a one year calendar
  • January 1st: Big Bang
  • February: Milky way formed
  • Early September: our solar system and planet
  • Late September: life on Earth
  • Mid-December: recognizable animals
  • Dec. 26th: dinosaurs
  • Dec. 30: dinosaurs died
  • Dec. 31st - 9pm: early hominids
  • 30 seconds ago: human civilization (pyramids 11 seconds ago, galileo and kepler 1 second)
36
Q

Dark matter

A
  • matter that is invisible by our telescopes, most of the mass of the galaxy
37
Q

Dark energy

A
  • astronomers first recognized when discovered that expansion of universe is getting faster with time
38
Q

Hubble’s Law

A
  • every galaxy outside local group is moving away from us
  • the more distant galaxy, the faster is moves away
  • This is how we know old the universe is, by how fast other things are moving away
  • Speed of recession of a galaxy is proportional to its distance from an observer
39
Q

Doppler shifts

A
  • measures speeds of galaxies by spreading light into spectra
40
Q

Copernican revolution

A
  • copernicus said sun is centre
41
Q

What are the terrestrial planets and how far are each from the Sun in AU?

A
  • Mercury (0.4 AU)
  • Venus (0.7 AU)
  • Earth (1 AU)
  • Mars (1.5 AU)
  • Terrestrial because made up of heavier materials; silicon and irons
42
Q

What are the Jovian planets and how far are each from the Sun?

A
  • Jupiter (5.2 AU)
  • Saturn (9.6 AU)
  • Uranus (19.2 AU)
  • Neptube (30.1 AU)
  • Made of gasses/ice; Jupiter and Saturn hydrogen and helium mostly; Uranus and Neptune (ice giants) water, ammonia and methane
  • All have a small icy rocky core
43
Q

Asteroid belt

A
  • few million asteroids

- large volume of space, orbiting Sun

44
Q

Keiper Belt

A
  • Past Neptune
  • ~30-50 AU
  • Icy, containing Pluto
  • 20x’s as wide and heavy as asteroid belt
45
Q

Oort Cloud

A
  • outer region
  • small icy objects
  • spherical shape
  • trillions of objects 1km in size, and billions of slightly larger ones
46
Q

Milky Way facts

A
  • Milky way is spiral shaped
  • We are 1.7 billion AU from centre in the Orion arm
  • 6-10 billion AU wide, and 120 million AU is thickness of disk
47
Q

Cosmology

A

scientific models of origin, evolution, and future of our universe

48
Q

Big bang

A
  • universe began from condensed point, expanded and cooled down

1) expansion and cooling
2) formation of atoms, clouds of atoms collapsed and form stars and planets
3) stellar nuclear fusion made heavier atoms
4) stars systems clustered together making galaxies
5) galaxies close together made local groups
6) larger clumps of galaxies = galaxy clusters

PHYS 284 - Astronomy (5 decks)

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