Astronomy S1 Practice Test Questions
The Sun's declination on June 21st is ______.
+23.5 degrees
Which of the following statements about sidereal and solar days is not true?
A sidereal day is the definition of a day on the Earth and a solar day is the definition of a day on the Sun.
What is the difference between a synodic month and a sidereal month?
A synodic month is the time it takes for a cycle of lunar phases and a sidereal month is the time it takes the Moon to orbit Earth (relative to the stars).
All the following statements are true. Which one explains why our calendar has leap years?
A tropical year is slightly more than 365 days.
Suppose you live at latitude 30°S. Which star is circumpolar in your sky?
Alpha Centauri
Which of the following best explains why a solar day is longer than a sidereal day?
Because Earth orbits the Sun at the same time it rotates, Earth must make slightly more than one full rotation between noon one day and noon the next.
Which of these stars lies closest to the north celestial pole on the celestial sphere?
Deneb
Which of the following explains why navigators prior to a few hundred years ago found it much more difficult to determine longitude than latitude?
Determining longitude requires an accurate clock, but latitude does not.
Suppose you live at latitude 40°N. Which of the following describes the path of the celestial equator through your sky?
It extends from due east on your horizon, to an altitude of 50° in the south, to due west on your horizon.
Which of the following best describes the Tropic of Cancer?
It is the circle of latitude on Earth for which the Sun appears directly overhead at noon on the summer solstice.
When should we next expect to observe a transit of the Sun by Mars?
Never.
It's the summer solstice, the Sun is at your zenith, and you have a UT clock that tells you it is midnight in Greenwich, England. Where are you?
On the Tropic of Cancer near the International Date Line.
Suppose that you are looking at the sky at about midnight on the winter solstice. Which star will be nearest to your meridian?
Sirius
Which of the following statements is not true about the sky at Earth's equator?
The Sun will pass directly overhead around noon each day.
Suppose Earth's axis had a greater tilt (more than 23.5 degrees). Which of the following statements would not be true?
The celestial sphere would be covered by a different set of constellations than it is with the current axis tilt.
All the following statements are true. Which one explains why mean solar time differs from apparent solar time?
The length of a solar day is not always exactly 24 hours.
Which of the following best describes the meaning of declination and right ascension?
They are coordinates on the celestial sphere, with declination telling us the angular distance of an object from the celestial equator and right ascension telling us how far around the celestial sphere an object is located from the vernal equinox.
A friend says she saw a planet shining on her meridian at midnight. Which planet can you be sure that she did not see?
Venus
What is the global positioning system (GPS)?
a system for determining positions on Earth using signals from a set of satellites in Earth orbit
Suppose you have a time-keeping device that always reads precisely 12:00 when the Sun crosses your meridian. What kind of time is this clock keeping?
apparent solar time
What kind of time can be read directly from a sundial?
apparent solar time
When we say that Jupiter is at opposition we mean that it ______.
appears on the opposite side of the sky from the Sun, so that it is on our meridian at midnight
As viewed from any place within the continental United States, noon on apparent solar time is defined as the moment when the Sun is ______.
directly south
The north celestial pole appears 30° above your horizon. The star Vega is on your meridian. By studying your star charts and your clocks, you determine that Vega crossed the meridian in Greenwich (England) 3 hours ago. Where are you?
latitude 30°N, longitude 45° west
If you were standing on Earth's equator, where would you look to see the north celestial pole?
on your horizon due north
Suppose it is January and the Sun remains above your horizon all day long. Where must you be located?
somewhere between the Antarctic Circle and the South Pole
From a latitude of 60 degrees north during the winter, the Sun will ______.
spend most of each day below the horizon
Our modern calendar is also known as ______.
the Gregorian calendar
Universal time, or UT, is ______.
the mean solar time in Greenwich, England
Suppose you know the declination of a bright star that is now crossing your meridian. What else must you measure in order to determine your latitude?
the star's altitude
