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Astronomy > Astronomy test #1 > Flashcards

Astronomy test #1 Flashcards

1
Q
  1. What is the closest astronomical body to the earth, and how far away is it?
A

The Moon is the closest astronomical body to the earth. It is 240,000 miles away (about a quarter of a million miles) It is Earth’s natural satellite. It orbits the Earth.

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2
Q
  1. Why is the Moon not called a planet? What type of a thing is the moon?
A

The moon is large enough to be a planet, but it technically isn’t called a planet because its orbit is centered on the Earth, not the Sun. For this reason, the Moon is called a satellite. Satellites orbit planets.

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3
Q
  1. Which planet has the most Moons?
A

Saturn has the most moons…146

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4
Q

What does the word “orbit” mean?

A

An orbit of a satellite is simply the path (trajectory) it takes around the planet.

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5
Q
  1. Why does the moon orbit the Earth?.
A

The moon orbits the Earth due to gravitational attraction. Gravity is the force that pulls objects with mass toward one another.

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6
Q

What type of thing is the Sun?

A

The Sun is the star at the center of the Solar System.

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7
Q

How many times larger is the diameter of the Sun compared to Earth?

A

The Sun’s diameter is 864,000 miles, or 109 times that of Earth,

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8
Q
  1. What is the Sun made of primarily?
A

Roughly three quarters of the Sun’s mass consists of hydrogen (~73%); the rest is mostly helium (~25%). So the Sun is mostly Hydrogen and Helium gases,

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9
Q
  1. How old is the Sun and the Solar System?
A

The age of the Sun and the Solar System is estimated to be around 4.6 billion years old.

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10
Q

What is the process in the Sun’s core that produces energy?

A

Nuclear Fusion is the process by which the Sun creates energy.

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11
Q

What is the order of the planets from closest to farthest from the Sun (MEMORIZE THIS)?

A

Mercury,Venus,Earth, Mars, Jupiter,Saturn, Uranus
Neptune

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12
Q
  1. What are a few differences between terrestrial planets and gas giant planets?
A

Terrestrial planets have relatively thin atmospheres compared to gas giants, Terrestrial planets have fewer moons and no prominent ring systems, Terrestrial planets are much denser than gas giants.

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13
Q

What is the habitable zone

A

the distance from a star at which liquid water could exist on orbiting planets’ surfaces. Habitable zones are also known as Goldilocks’ zones, where conditions might be just right – neither too hot nor too cold – for life.

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14
Q

What are asteroids and where are most of them found?

A

Most asteroids exist in a belt between the orbits of Mars and Jupiter…called the asteroid belt
Asteroids are relatively small rocky bodies.

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15
Q

Which is the largest asteroid, and how large is it.

A

the largest, Ceres, is almost 1,000 km (600 miles, the size of Texas) in diameter, and massive enough to qualify as a dwarf planet

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16
Q
  1. What is an astronomical unit?
A

An Astronomical unit (au), is a unit of measurement, equal to 93 million miles. That’s the average distance of the earth from the Sun. So the Earth is 1 au from the Sun.

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17
Q
  1. What is the Kuiper Belt? Where does it lie? How far away from the Sun is it?
A

The Kuiper Belt is a region of the solar system beyond the orbit of Neptune (the last planet). It extends from 30 au, to 55 au.

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18
Q
  1. What are TNOs?
A

All objects beyond Neptune are called trans-Neptunian Objects (TNOs). Some are in the Kuiper belt (like Pluto), and some are beyond the Kuiper Belt (like Sedna).

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19
Q
  1. What is a comet?
A

A comet is a celestial object composed primarily of ice, dust, rocky material, and organic compounds.

20
Q
  1. What is meant by orbital period of a planet (or comet, asteroid, etc)?
A

The orbital period of a celestial object, such as a planet, comet, or asteroid, refers to the time it takes for that object to complete one full orbit around another object, typically a star like the Sun or a planet like Earth.

21
Q
  1. Where do long period comets come from?
A

Long period comets come from beyond the Kuiper belt, some as far away as the Oort cloud (next slide). They have orbital periods of 200 years or more.

22
Q

What is the Oort cloud?

A

Oort cloud is a reservoir of long period Comets (Comets that take a long time to orbit the Sun)

23
Q

What is meant by “interstellar space”

A

Interstellar space refers to the vast regions of space that exist between stars within a galaxy.

24
Q

What is a star?

A

A star is an astronomical object consisting of a hot, luminous, sphere of plasma (a form of gas) held together by its own gravity. Stars, unlike planets, are self-illuminating. Stars are powered by intense nuclear fusion reactions in their cores.

25
Q

How was a light year determined? What is the advantage of using units of light years (ly) to

   measure the distances to the stars?  Why isn’t the astronomical unit (au) used for this  

    purpose?
A

A light year (ly) is a unit of astronomical distance equivalent to the distance that light travels in one year, which is about 6,000,000,000,000 (6 trillion) miles. When examining the stellar distances, It is much more convenient to define the distance using light years, not miles, or astronomical units.

26
Q

Which is larger: an astronomical unit, or a light year?

A

A light year is significantly larger than an astronomical unit (AU).

An astronomical unit (AU) is the average distance from the Earth to the Sun, approximately 149.6 million kilometers (about 93 million miles).

In contrast, a light year is the distance that light travels in one year, which is approximately 9.461 trillion kilometers (about 5.879 trillion miles).

27
Q

light year formula

A

distance in miles divided by 5.879 trillion

28
Q

What is the closest star to the Earth? How far away is it in light years?

A

Proxima Centauri, the closest star to our Solar System Proxima Centauri is 4.24 light years away.

29
Q

What is an exoplanet? Google this: “how many confirmed exoplanets are there?”

    So, how many known are there?
A

5,000 confirmed . a planet that orbits a star outside the solar system

30
Q

What is a nebula?

A

A nebula is a cloud of gas in interstellar space

31
Q

What is the Interstellar Medium?

A

The Interstellar Medium - the space between the stars

Mostly gas (98%), a little bit of dust (2%)

32
Q

What is the difference between an open star cluster, and a globular star cluster?

A

Globulars
-have many more stars than open clusters,
-are much older (in fact the oldest objects in the galaxy),
-and stay together as a group because of their gravity.

33
Q

What is the relationship between a star’s temperature, color, and its lifespan?

A

The color of a star tells us its temperature.
Blue stars are hottest, than white, yellow, orange and finally red. Red stars are the coolest. The correlation between a star’s temperature, color, and its lifespan, with hotter, bluer stars typically having shorter lifespans due to their higher mass and faster consumption of nuclear fuel, while cooler, redder stars tend to have longer lifespans because of their lower mass and slower rate of fuel consumption.

34
Q

What is the habitable zone around a star?

A

The Circumstellar Habitable Zone (CHZ), or simply the habitable zone, is the range of orbits around a star within which a planetary surface can support liquid water given sufficient atmospheric pressure.

35
Q

What type of star is the least luminous in the universe?

A

The least luminous stars in the universe are known as brown dwarfs. Brown dwarfs are substellar objects that are not massive enough to sustain stable nuclear fusion in their cores, which is the process that powers stars like the Sun.

36
Q

What is a galaxy?

A

A galaxy is a system of stars, stellar remnants, interstellar gas, dust, dark matter, bound together by gravity.

37
Q
  1. Give a brief description of the Milky Way: shape, size, number of stars
    What type of galaxy is it?
A

The Milky Way is our Galaxy. It is a type of Spiral Galaxy known as a Barred Spiral. Notice the bar in its center. and the two spiral arms attached to the ends of the bar.

The Milky Way is at least 100,000 light years across (it takes light 100,000 years to cross it). Some research suggests it might be twice this size.

The Sun, an average star, is one of 250 billion stars in the Milky Way

38
Q
  1. Why can’t we get a picture of the entire Milky Way?
A

Dust clouds within the Milky Way absorb and scatter visible light, obscuring our view of distant stars and regions within the galaxy. This dust can block our line of sight and prevent us from seeing objects located behind it.

39
Q

3 main types of galaxies

A

Basically, the three major galaxy types are: spiral, elliptical and irregular

40
Q

What is the closest spiral galaxy to our own? How far away is it? How many stars does it

   have?
A

The Andromeda Galaxy is the closest spiral galaxy to the Milky Way. It is bigger and has more stars than the Milky Way

The Andromeda Galaxy is 2 ½ million light years away

41
Q

What is the “Local Group”? What is a “Supercluster”?

A

The Local Group is a local galaxy group of about 80 galaxies that includes three spirals: the Milky Way galaxy, Andromeda galaxy .A supercluster is a group of groups.

42
Q

What are the largest structures the Universe?

A

Galaxy filaments are the largest known structures in the universe.

43
Q

How many galaxies are there?

A

As of the latest estimates, there are billions of galaxies in the observable universe

44
Q
A
44
Q

How far is the farthest galaxy ever seen? How long did it take its light to get here?

A

The most distant confirmed galaxy is JADES-GS-z13-0, which was also discovered by the JWST in 2022 with a distance of 13.4 billion light years.

Astronomy (1 decks)

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