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Astronomy
| Term | Definition |
|---|---|
| Northern Lights | Steams of electrons from Earth's magnetosphere rain down on the atmosphere below, stimulating oxygen and other atoms to shine. |
| Mean Solar Time | Time as calculated by the motion of the mean sun. The time shown by an ordinary clock corresponds to mean solar time. |
| Sideral Day | The time between two consecutive transits of the First Point of Aries. It represents the time taken by the earth to rotate on its axis relative to the stars, and is almost four minutes shorter than the solar day because of the earth's orbital motion. |
| Why We Have Seasons | The earth is tilted (wonky) as it makes its yearly journey around the sun. The Earth's axis is tilted at an angle of 23.5 degrees. This means that the Earth is always "pointing" to one side as it goes around the Sun. |
| Why The Moon Has Phases | It orbits Earth, which causes the portion we see illuminated to change. |
| When Lunar Eclipses Occur | Occur when a full moon is exactly on the line from the sun to the Earth. You can still see the moon, although it's immersed in Earth's shadow. |
| Why One Side Of The Moon Is Always Lit | The moon makes exactly one turn on its axis as it makes one orbit around Earth (synchronous rotation). |
| Impact Crators | A crater on a planet or moon caused by the impact of a meteorite or other object, typically circular with a raised rim. |
| Rilles | A fissure or narrow channel on the moon's surface. |
| Rays | Bright lines formed by powdery debris thrown out from some impacts. |
| The Difference Between Old and New Surfaces Of The Moon | Old craters have a rounded look to them, while fresher craters are sharp-edged, and show the debris from impact. |
| Differences Between Moon Rocks and Earth Rocks | Earth rocks in their various forms are usually formed under conditions of great heat and great static pressure. Unheated moon rocks are mostly grain and dust, heated rocks have crystals in them. |
| The Giant Impact Theory | The idea that a catastrophic collision about 4.5 billion years ago between Earth and a protoplanet about half Earth's size created a disk of molten rock, gas and debris that consolidated to form the moon. |
| What Causes A Solar Eclipse | Occurs when the moon gets between Earth and the sun, and the moon casts a shadow over Earth. Only last about 5 minutes. |
| Why A Solar Eclipse Cannot Be Seen Everywhere On Earth | People who are to not within the umbra cannot see a solar eclipse. |
| What Causes A Lunar Eclipse | A lunar eclipse occurs when the Moon passes directly behind the Earth into its umbra (shadow). This can occur only when the sun, Earth and moon are. |
| What Moon Phase Is It During A Solar Eclipse | New moon |
| What Moon Phase Is It During A Lunar Eclipse | Full moon |
| Why Not Everyone Can See A Total Solar Eclipse | Not everyone is within the location of a solar ellipse (not in the umbra). |
| Umbra | The darkest part of a shadow, especially the cone-shaped region of full shadow cast by Earth, the Moon, or another body during an eclipse. I |
| Penumbra | A space of partial illumination (as in an eclipse) between the perfect shadow on all sides and the full light. |
| During Which Season (summer or winter) has the longest daylight hours? | Summer. 15 hours |
| What season is the sun the highest in the sky? | Summer sostice |
Created by:
Blissful_Olive
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