Ch. 21 - MG ch. 21
True
An eclipse of the Moon can be seen by anyone on the side of Earth facing the Moon.
0
At the beginning of spring, the vernal equinox, what is the right ascension of the sun?
The ellipticity of the orbit is small, so the affect is small; seasons are caused by tilt of the earth's orbit.
Earth hits its perihelion position in January. Solar radiation is proportional to the distance squared between the sun and the earth, so why isn't it hot in "winter" at perihelion?
The other visible stars appear to rotate around Polaris.
How can people on Earth tell that the axis of the planet points toward Polaris?
the same amount of time it take for one revolution around Earth
How long does it take the Moon to rotate once on its own axis?
True
Lunar eclipses last longer than solar eclipses.
false
Solar eclipses are more common than are lunar eclipses.
sidereal
The ________ day is the time it takes for Earth to make one complete rotation with respect to a star other than our Sun.
determine when to plant crops or hunt animals based on seasonal changes
The earliest astronomical records appear to have been made by the ancient Chinese, Egyptians, and Babylonians in order to ________.
seasons
The offset between the axial tilt of the Earth and its original vertical orientation gives us periodic changes at the Earth's surface called __________.
true
The same side of the Moon is always visible from Earth.
Sir Isaac Newton
This scientist determined the nature of the forces that kept the planets in their orbits.
Johannes Kepler
Three laws of planetary motion were discovered by ________.
23.5 degrees
What is the current angle of axial tilt for the Earth?
the plane in which the Earth orbits the Sun
What is the ecliptic?
circumference of the Earth
When Eratosthenes was using the well at Syene and the obelisk at Alexandria to study the Earth, what statistic was he trying to calculate?
it is rotating around the sun slower than the earth's rotation
When viewing the planets, Mars appears to move backwards, or retrograde, because ________.
Several degrees from the North Pole position, with Vega as the North Star.
Where will the North Star be, relative to the celestial coordinates, 12,000 years from now?
Little Dipper
Which constellation contains Polaris?
Polaris
Which star lines up perfectly with the Earth's axis of rotation, giving it a nearly stationary appearance in the night sky?
It demonstrated that Venus could not be in orbit around earth between earth and the sun because it shows "full" and "new" phases that would never occur with geocentric geometry.
Why did Galileo's observation that Venus showed phases like the moon indicate that the geocentric theory of the solar system was not possible?
