Astronomy

Today, distances to stars are measured by

geometry.

Today, distances to stars are measured by...

geometry.

As the size of baseline increases, parallax

increases

Which of the following is NOT true when the Sun has declination = 0 degrees

it is the summer solstice

If Earth orbited the Sun in 9 months instead of 12, then, compared with a sidereal day, a solar day would be

longer.

How often does a new moon occur?

once a month

A sidereal month is...

one moon orbit around Earth

Waxing

the illuminated part of the moon getting bigger

Waning

the illuminated part of the moon getting smaller

We see a "half moon" in our sky only when...

the moon is 1/4 or 3/4 of the way around its orbit

A synodic month is...

the time from one new moon to the next new moon *one full cycle of moon phases*

A sidereal day is...

the time it takes for any star to go from being on the meridian one day until it is again on the meridian the next day *one rotation of Earth on its axis*

If the Moon's orbit were a little larger, solar eclipses would be...

more likely to be annular.

If the Moon orbited Earth twice as fast, but in the same orbit, the frequency of solar eclipses would

stay the same.

A long, thin cloud that stretched from directly overhead to the western horizon would have an angular size of

90º

If you could change the layout of the solar system, which of the following would cause a lunar eclipse to occur at least once every month in this hypothetical situation?

Change the Moon's orbital plane so it is in the same plane as Earth's orbit around the Sun.

A lunar eclipse occurs when...

Earth's shadow falls on the moon

T or F? Earth's shadow falls on the Moon during every full season

False

T or F? The Moon's shadow falls on Earth during every new moon

False

The period-luminosity relation for Cepheid variables was discovered in 1908 by:

Henrietta Leavitt.

Compare the size of Earth with that of the Sun, the Milky Way galaxy, and the entire universe.

Looking at the data in the text, we can see that the diameter of the Sun is about 100 times that of Earth, about 1,500,000 km for the Sun compared to about 12,000 km for Earth. A galaxy such as the Milky Way is about 100,000.

What conditions must exist for a lunar eclipse to occur?

The phase of the Moon must be full and the Moon must be passing through Earth's orbital plane

What conditions must exist for a lunar eclipse to occur?

The phase of the Moon must be full and the Moon must be passing through Earth's orbital plane.

What conditions must exist for a solar eclipse to occur?

The phase of the Moon must be new and the Moon must be passing through Earth's orbital plane

What conditions must exist for a solar eclipse to occur?

The phase of the Moon must be new and the Moon must be passing through Earth's orbital plane.

What is the scientific method, and how does science differ from religion?

The scientific method is a process for discovering the best possible explanation as to why something occurs. The process begins when observations lead to the formulation of a hypothesis, a preliminary explanation.

We see about 3/4 of the Moon's face illuminated at waxing gibbous phase. What do we see about 3 to 4 days later?

a full moon

Consider the Moon and Sun. Their angular diameters are both equal to about .5 degree. If the Sun is roughly 400 times more distant than the Moon, how much bigger is the Sun's diameter than the Moon's?

about 400 times bigger

When a thin crescent of the Moon is visible just before sunrise, the Moon is in its...

waning phase

summer solstice

-longest day (most daylight) of the year -the noontime Sun reaches its highest point of the year

fall equinox

-the Sun has declination 0 degree today, but will have a negative declination tomorrow -sept 21-24

winter solstice

-the Sun crosses the meridian 23.5 degrees lower in altitude than the celestial equator -sunset occurs at its farthest point south of due west for the year -the noontime Sun casts the longest shadows

Write this number in scientific notation: 123,000.

1.23 × 10^5

Suppose that instead of being inclined to Earth's orbit around the Sun, the Moon's orbit was in the same plane as Earth's orbit around the Sun. In this hypothetical situation, approximately how many solar eclipses would occur each year?

12

In reality, the Moon's orbit about Earth is tilted (by about 5°) with respect to Earth's orbit about the Sun. As a result, the actual number of solar eclipses that occur each year is approximately _____.

2

in January the Sun is in the constellation

Aquarius.

T or F? A full moon occurs when the Sun and the Moon are on opposite sides of Earth

True

T or F? A new moon occurs when the Sun and the Moon are on the same side of Earth

True

The Moon's shadow always points directly...

away from the sun

As the distance to the object increases, parallax...

decreases

As the distance to background objects increases, parallax

remains the same

We see a full moon in our sky only when...

the Moon and Sun are on opposite sides of Earth

A solar eclipse occurs when...

the Moon's shadow falls on Earth

-the Sun rises due east today, but will rise slightly north of due east tomorrow -the equinox occurs at two specific moments in time when the sun is exactly above the equator

the Sun rises due east today, but will rise slightly north of due east tomorrow