Celestial coordinates
This date is when the right ascension of the Sun is 0 hours.
What is the Vernal Equinox?
This planet has a runaway greenhouse effect, and is the hottest in the Solar System.
What is Venus?
The phenomenon that causes the Earth's north star to change.
What is Axial precession?
This planet's anomalous motion inspired Kepler's First Law (Planets move in elliptical orbits).
What is Mars?
The phase of the Moon where it is half lit.
What is the First/Third Quarter?
The position in the sky directly overhead.
What is the zenith?
This planet's motion requires General Relativity to explain.
What is Mercury?
The calendar that uses the phases of the Moon to track the Solar year.
What is the lunisolar calendar?
Neptune's orbital semi-major axis is 30.07 AU. What is it's period?
P=164.9 Earth years
The accepted hypothesis for the formation of the Moon.
What is the giant-impact hypothesis?
The latitudes on Earth where the Sun can appear directly overhead.
What are the tropics?
This moon experiences volcanism due to heating from tidal friction.
What is Io
What led Eratosthenes to view the Earth as round rather than flat?
The shadows cast at Alexandria and Syene on the summer solstice.
Titan orbits Saturn with semi-major axis a=1.22 Gm and orbital period P=15.95 days. Find the semi-major axis of Phoebe (another moon orbiting Saturn) if Phoebe has orbital period P=550 days.
a=12.9 Gm
When the Earth, Moon, and Sun are arranged
Sun -> Earth -> Moon
Meaning "[The sun] turns around", these events mark the times of year when the Sun is at its highest/lowest point in the sky.
What are the Summer/Winter solstices?
This planet experiences 42 years of continuous day and 42 years of continuous night throughout the year.
What is Uranus?
The 12 constellations that lie on the Sun's path throughout the year.
What is the zodiac?
The Great Comet of 1882 has Apogee Ap=153.5 AU and Perigee Pe=0.0077 AU. Find it's orbital eccentricity.
e=0.9999
The time when a Third Quarter Moon crosses the meridian.
What is 6 am?
Jupiter's right ascension is 8 hours. When is the best time to observe it?
January
The only planet to be predicted mathematically before observationally confirmed.
What is Neptune?
Thuban was the north star to ancient astronomers in 3,000 B.C. When will it be the North star again?
23,000 A.D.
Exoplanet WASP-67 b orbits a distant star at a=0.05179 AU with orbital period of P=4.6 days. What is the mass of its host star?
0.876 M_Sun
Why is the lunar cycle (29.5 days) different from the Moon's orbital period (27.3 days)?
The Earth moves in its orbit around the Sun.