AstronomyCheatSheet - The celestial equator is a line...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
The celestial equator is a line around the sky directly above Earth's equator and the dividing line between the north and south celestial hemispheres. From a latitude of 20° N the altitude of the north celestial pole (and the star Polaris) is 20° above the north point. Stars that never appear to set are called circumpolar. As you move from Earth’s equator toward the North Pole, the number of stars that are circumpolar increases. The sun crosses the celestial equator twice a year on the equinoxes. If the sun sets directly west on the Vernal Equinox, then three weeks later it will set north of west. The altitude of the sun’s rays and the amount of time that the sun is above the horizon contributes to the seasons. At any give time, the most amount of the moon’s surface you can see is only 50%. If the moon is full tonight, one week from now it will be a third quarter moon. A third quarter moon rises at midnight . A full moon rises when the sun sets. The moon rotates once per month. A total solar eclipse can only occur at new moon. The major factor that governs whether a solar eclipse is total rather than annular is the distance between the moon and the Earth. The moon does not look completely dark when it is in the Earth’s shadow during a total lunar eclipse because the Earth’s atmosphere bends bed sunlight onto the moon. If the plane of the moon’s orbit were to be the same as the ecliptic plane, there would be a lunar eclipse once every month. Eclipse of the moon can only occur at full moon. Planet is derived from a Greek term meaning “ wanderer .” Retrograde motion of a planet is the westward motion against the star background. The Copernican system for planetary motions is Sun-centered, with the planets moving in perfect circles around the Sun.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 01/27/2012 for the course CHEM 121 taught by Professor 1212 during the Spring '11 term at University of Illinois at Urbana–Champaign.

Page1 / 2

AstronomyCheatSheet - The celestial equator is a line...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online