Astro Hw 2 Pt 2

How is the sidereal day defined? Why do the sidereal and solar days differ in length?

A sidereal day is day length that is measured in respect to the stars. Sidereal days differ in length to solar days because they are more precise in measurement in comparison to solar days. The Earth needs to rotate more before the sun is on the meridian again, in comparison of one certain day to a different day. This extra rotation makes the solar day slightly longer than the sidereal day.

Where is the Sun located on the celestial sphere during the equinoxes and solstices?

During summer solstice, the sun lies 23.5 degrees North of the Celestial Equator. The declination of that is +23.5. During winter solstice, the sun is located at a declination of -23.5 degrees south to the Celestial Equator. During vernal equinox, the Sun lies directly on the Celestial Equator. This would be defined as an ascension of 0h. It is moving from the Southern Hemisphere of the celestial Sphere into the Northern Hemisphere. During autumnal equinox, the sun is again at 0h in ascension, lying on the Celestial Equator, as it makes its way from the Northern Hemisphere into the Southern Hemisphere

How does the Sun's position on the horizon at sunset change through the course of the year?

During the vernal equinox to summer solstice, the sunset is located slightly north of due west. This switches at summer solstice going to winter solstice and the sunset will begin to be slightly south of due west. The only point where the sun is directly west on the horizon during sunset is during vernal equinox.

Why are "leap seconds" added to our clocks every few years?

Leap seconds are added to clocks every few years to make sure that all atomic clocks are in agreement as to what time it is.The Earth is slowing down in rotation, while extremely minimal, due to the interaction of the spinning Earth with ocean tides. Because of this interaction, there is a difference in time every year, and leap seconds are added so that all time is in agreement between all atomic clocks. These leap years realign time with Earth's rotation.

From what location on Earth will the Sun always rise due east and set due west?

Nowhere

What is the slow shift of the position of the celestial poles?

Precession

For someone in the Southern Hemisphere, which of the following is correct?

The Sun rises in the southeast on December 21.

What is the ecliptic? What is the zodiac?

The ecliptic is the path the Sun makes when it traces across the celestial sphere. The zodiac, which means "animals" and circle," is the group of twelve constellations that the ecliptic passes as the Sun traces across the sky.

Where is the meridian located?

The meridian is the line that is located where it separates the eastern and western halves of the sky. It extends from the point of the horizon due north to the point due south and passes through the zenith.

What is universal time?

Universal time is time that does not differ in any time zone. It is based on a 24 hour system and is kept in the time zone containing the longitude zero. This measurement of time is universal, meaning anyone on any time zone can use it to see the exact time of UT, without being affected by their time zone.

What effect does precession of the Earth's rotation axis have on the Sun's location in theZodiac?

The precession of Earth's rotation axis does not alter its orbit, therefore not changing the ecliptic or the constellations of the zodiac. What it does change is the certain zodiac constellation that the Sun is in during the equinoxes and solstices. This is shown due to the fact that the first day of summer landed on the constellation of Cancer, giving us the Tropic of Cancer. This changed due to precession and the first day of summer shows the Sun being in Gemini

What causes the seasons?

The reason we have seasons is due to the 23.5 degree tilt that the Earth has in relation to the orbit it makes around the Sun. As the Earth goes around the Sun, it keeps the same tilt and direction. This causes certain areas of Earth to receive sunlight at a more direct angle, thus creating a hotter season. Since the tilt stays constant, Earth gets more sunlight in the Northern Hemisphere for half of the year, then more sunlight in the Southern Hemisphere for the other half of the year.

On what day(s) of the year are nights longest at the equator?

They are the same length throughout the year there.

Earth's orbit around the Sun has what effect on the rising time of non- circumpolar stars?

They rise several minutes earlier each night.

How does time shift across the International Date Line?

Time shifts across the International Date line by switching the day you are in when you are crossing. You either have to go forward a day or take a day back.

Why is the summer solstice not the hottest day of the year?

While summer solstice is the longest day of the year, it is not the hottest because the Earth's land masses and oceans have yet to heat up. Typically, the hottest weather will come after Summer Solstice occurs. After a month or two of the summer solstice, real heat will begin to occur. This is called the lag of the seasons

In which of the following locations is the length of daylight 12 hours throughout the year?

a. Only on the equator

If the Earth began orbiting the Sun twice as fast as it does now, the length of a solar day would

become slightly longer

In which of the following locations can the length of daylight range from zero to 24 hours?

d. At latitudes greater than 66.5° north or south

During summer in either hemisphere the temperature is higher because the Su

is higher in the sky during the day.

Daylight saving time

results in the Sun crossing the meridian around 1 p. m.