Unit 2 Our Solar System Flashcards

1
Q

Name the 8 planets in order.

A

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

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2
Q

Name the four “terrestrial” planets.

A

Mercury, Venus, Earth and Mars.

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3
Q

Name the four gas giants.

A

Jupiter, Saturn, Uranus and Neptune.

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4
Q

Estimated number of natural satellites (moons) in the Solar System.

A

160, and the number keeps growing.

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5
Q

Name three dwarf planets.

A

Ceres, Pluto and Eris.

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6
Q

What are asteroids?

A

Small (mostly less than 100km in size but larger than 10m) solid bodies. The majority orbit in the Asteroid or Main Belt between Jupiter and Mars. An example is Vesta.

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7
Q

Describe a comet.

A

Comets have a nuclei of ice, dust and rock that develops a gaseous coma. The comet develops tails when close to the Sun. The ion tail is in the opposite direction to the Sun and the dust tail is in the direction that the comet has travelled from. An example is Halley’s Comet.

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8
Q

What are centaurs?

A

Centaurs show similarities to both asteroids and comets. Centaurs generally orbit the Sun between Jupiter and Neptune. Centaurs include Chiron.

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9
Q

What are TNOs?

A

TNO stands for Trans-Neptunian Object. These are objects that orbit the Sun beyond Neptune.

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10
Q

The IAU (International Astronomical Union) defines a planet must/be what three things?

A

Must orbit the Sun.
Be large enough to be spherical.
Be able to clear it’s orbit of other objects.

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11
Q

What is 1AU (Astronomical Unit) and how long is it?

A

1AU is the average distance from Earth to the Sun and this is 150 million km.

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12
Q

Which planet spins the opposite direction to the other planets?

A

Venus

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13
Q

How many times greater is the surface pressure on Venus than on Earth?

A

90 times greater.

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14
Q

What is the surface temperature on Venus?

A

470 degrees Celcius.

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15
Q

What is the general description of Venus’ atmosphere?

A

A runaway greenhouse effect.

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16
Q

Mars has a surface rich in which metal?

A

Iron

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17
Q

Mars is home to the tallest what in the Solar System?

A

Volcano - Olympus Mons.

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18
Q

Jupiter rotates on its axis in how many hours?

A

10 hours. This produces a large equatorial bulge that then causes a dynamic wind system. This wind system splits the atmosphere into two.

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19
Q

What is Jupiter’s Giant Red Spot (GRS)?

A

It is an anticyclone weather system that is larger than Earth.

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20
Q

Saturn has a similar or different atmosphere to Jupiter?

A

Similar but without the weather systems.

21
Q

Saturn’s most prominent features are…

A

…it’s rings.

22
Q

True or false Uranus spins vertically?

A

False it spins almost on its side.

23
Q

Most of our scientific data about the Solar System has been collected by what?

A

Scientific instruments on unmanned space probes.

24
Q

Manned space missions have been restricted to where?

A

The Moon.

25
Q

Why have space missions not gone past the Moon?

A

The time it takes and the tremendous costs involve?

26
Q

Other problems with manned space flight.

A
Space Adaptation Syndrome (no up and no down).
Brittle bones etc.
Communication delays.
Radiation risk.
Psychological problems.
27
Q

It can be argued that robotic exploration can do just as good a job as manned exploration because…

A

…it is cheaper and safer.

28
Q

Describe a moon.

A

A natural satellite that obits a planet.

29
Q

True or false. The number of moons continues to decrease?

A

False. The number of moons continues to increase as new moons get discovered.

30
Q

Mars has two moons. What are their names?

A

Deimos and Phobos

31
Q

Most scientists believe that Mars gained its moons how?

A

It may have captured them from the asteroid belt.

32
Q

What is Triton?

A

It is one of Neptune’s moons and is the only moon in the Solar System to orbit its planet in the opposite direction to the direction the planet rotates.

33
Q

Which planets have rings?

A

All of the gas giants, however Saturn’s are most prominent.

34
Q

What is the origin of a planet’s rings?

A

The origin of a planet’s rings are still unknown although they may have been left over from the formation of the planet; debris from impacts or material ejected from the surface.

35
Q

What is the shape of a planet’s orbit?

A

An ellipse (squashed circle).

36
Q

What is the name of the plane that the planets in our Solar System orbit on?

A

The ecliptic.

37
Q

What are of the sky do planets move through as a result of them all being on the ecliptic?

A

The Zodiacal Band.

38
Q

Relative positions of the planets determine how easily they can be observed. What are the groups of planets in relative position to the Earth?

A

Inferior planets (Mercury and Venus) and superior planets (Mars to Neptune).

39
Q

Why are inferior planets slightly harder to spot?

A

Because they orbit closer to the sun so never appear far away.

40
Q

When are Mercury and Venus best viewed?

A

At the Greatest Eastern Elongation (GEE) and Greatest Western Elongation (GWE). This is when the angle between the lines planet-Earth and planet-Sun is 90 degrees.

41
Q

When is a inferior planet visible at the GEE and GWE?

A

In the sunset (GEE) and sunrise (GWE).

42
Q

Why is Venus sometimes referred to as the Morning or Evening Star?

A

Because it has such a highly reflective surface it looks like a star on the sky.

43
Q

What is conjunction?

A

When an inferior planet is at elongation of 0 degrees. It is at superior conjunction when it is on the opposite side of the Sun to the Earth and it is at inferior conjunction when it passes between the Earth and the Sun.

44
Q

What is transit of an inferior planet?

A

When the planet passes across the surface of the Sun when viewed from Earth (during inferior conjunction).

45
Q

What is occultation?

A

When an inferior planet travels through superior conjunction and disappears from view from Earth.

46
Q

What is opposition of a planet?

A

When a superior planet is at its closest to Earth offering best resolution.

47
Q

What is direct motion of a planet?

A

The movement of a planet across the sky.

48
Q

What is the stationary point of a planet?

A

The point in its movement across the sky where it appears stationary before changing direction.

49
Q

What is retrograde motion of a planet?

A

When a planet appears to move in the opposite direction across the sky. This is caused by the Earth overtaking or undertaking planets during its orbit.