Astronomy Exam 1

Kepler's second law says that

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For Earth P^2/A^3 (in appropriate units). Suppose a new dwarf planet is discovered that is 14 times as far from the Sun as Earth ids. For this planet,

P^2/A^3 = 1.0

Constellations

-Constellations are arbitrary patterns of stars in the sky. In general, the stars in any constellation are not physically related to one another and are located at different distances from the Earth. -In that sense, they are just products of human imagination.

Celestial poles

-Each day, the celestial sphere appears to rotate around two poles. These are called the north celestial pole and the south celestial pole.

Celestial Sphere

-It is sometimes convenient to think of the sky as a large sphere centered on the Earth. This is called the celestial sphere. -This is a fiction, as the planets and the stars are all at very different distances from the Earth. -The points on the sphere correspond to directions rather than distance. It is a useful way to map positions of stars and objects in the sky.

Celestial equator

-Midway between the two poles is the celestial equator. In fact, the celestial equator is an extension of Earth's equator.

Circumpolar stars

-No star rises or sets. All are constantly above the horizon. Such stars are called circumpolar stars.

Zodiac

-The Sun's motion on the ecliptic along the zodiac is a reflection of Earth's orbit around the Sun. -Those constellations in the zodiac were given special distinction because the Sun passed through them on its path across the sky.

Ecliptic

-The path of the Sun across the sky is called the ecliptic, and it appears on the celestial sphere as a circle inclined 23.5 degrees from the celestial equator. This is because Earth's axis is tilted 23.5 degrees from the plane of its orbit around the Sun (the ecliptic).

Meridian

-With good timepieces, longitude can be determined by measuring when the Sun (or other objects) cross the meridian.

Dwarf planet Ceres is located at 2.77 AU from the Sub. Its synodic period is 1.278 years. a. Use Working It Out 3.1 to find the sidereal period in years. b. Use Kepler's law to find the sidereal period in years. c. Compare your results for (a) and (b).

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Suppose you read in the newspaper that a new planet has been found. Its average speed in orbit is 33 km/s. When it is closest to its star it moves at 31 km/s, and when it is farthest from its start it moves at 35 km/s. This story is in error because

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The speed of a planet in its orbit varies in its journey around the Sun. At what point in its orbit is the planet moving the fastest? At what point is it moving the slowest?

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If an event were to take place on the Sun, how long would it take for the light it generates to reach us?

8 minutes

There is an angle between the ecliptic and the celestial equator because

Earth's axis is tilted with respect to its orbit.

A lunar eclipse occurs when WHAT's shadow falls on WHAT

Earth's shadows fall on the Moon.

Rank the following in order of increasing size: Local Group Milky Way Solar System Universe Sun Earth Laniakea Supercluster Virgo Supercluster

Earth, Sun, Solar System, Milky Way, Local Group, Virgo Supercluster, Laniakea Supercluster, Universe

On the summer solstice in June, the Sun will be directly above WHAT and all locations north of WHAT will experience daylight all day.

The Tropic of Cancer; The Arctic Circle

The Sun, Moon, and stars

appear to move each day because the celestial sphere rotates about Earth.

Constellations are groups of stars that

are close to each other in Earth's sky.

When we observe a star that is 10 light-years away, we are seeing that star

as it was 10 years ago.

Where on Earth can you stand, and over the course of a year, see the entire sky?

at the equator.

A light-year is a measure of

distance.

Which is not true on the vernal and autumnal equinoxes?

every place on Earth as 12 hours of daylight and 12 hours of darkness.

When Earth catches up to a slower-moving outer planet and passes it in its orbit, the planet

exhibits retrograde motion.

Suppose a planet is discovered orbiting a star in a highly elliptical orbit. While the planet is close to the star it moves WHAT, but while it is far away it moves WHAT.

faster; slower.

Why do we not see a lunar eclipse each time the Moon is full or witness a solar eclipse each time the Moon is new?

http://earthsky.org/space/why-isnt-there-an-eclipse-every-full-moon

Occam's razor states that

if two hypotheses fit the facts equally well, the simpler one is the more likely to apply.

Copernicus' model of the Solar System was superior to Ptolemy's because

it had a mathematical basis that could be used to predict the positions of planets.

Polaris, the North Star, is unique because

it is the only star in the sky that doesn't move throughout the night.

An empirical science is one that is based on

observed data.

The cosmological principle states that

on a large scale, the universe is the same everywhere at a given time.

You see the first quarter Moon on the meridian. Where is the Sun?

on the western horizon.

Galileo observed that Venus had phases that correlated with its size in his telescope. From this information, you may conclude that Venus

orbits the Sun.

Which stars we see at night depends on

our location on Earth, Earth's location in its orbit and the time of the observation.

Galileo observed that Jupiter has moon. From this information, you may conclude that

some things do not orbit Earth.

We always see the same side of the Moon because

the Moon rotates on its axis once for each revolution around Earth.

The tilt of the Earth's axis causes the season's because

the days are longer in summer, and the rays of light strike the ground more directly.

Day and night are caused by

the rotation of Earth on its axis.

You see the Moon on the meridian at sunrise. The phase of the Moon is

third quarter.