Astronomy Assessment #2 Study Guide
What is a "blue moon"?
A "Blue Moon" is the 2nd Full Moon during 1 calendar month
When does a total eclipse happen?
A total eclipse happens only once every hundred years or so, though for selected locations they can occur as little as a few years apart.
The tail of the comet?
Always points away from the sun
Why do we always see the same side of the moon?
Because the moon revolves around the Earth and rotates on its axis at the same rate
Craters
Circular depressions on the moon's surface formed by impacts and it is approximately 30,000 are visible from Earth
What is a Comet?
Composed mostly of rock and ice, comets orbit the Sun and originate in an area called the Oort Cloud -a region past Pluto consisting of debris from the early formation of our solar system.
Maria
Dark, flat areas on the moon, Early astronomers thought they were "seas", Craters were filled with lava after meteorite impacts around 3 - 4 Billion years ago
How big is the Moon?
Diameter of the moon is about 1/4 that of the Earth and the moon's gravity is 1/6 of Earth's
Why is Venus Hot?
Due to some Greenhouse Effect
Why do we have seasons?
Earth has seasons because of its 23.5* axis tilt
Why do we see less impact craters on Earth than on the Moon or Mars?
Earth has very few visible impact craters because of the constant weathering & erosion
What is a Lunar Eclipse?
Earth's shadow on the Moon
Why Venus hotter than Mercury even though Mercury is closer to the Sun?
It has thicker atmosphere than Mercury
Where is the asteroid belt? How did it form?
Located between the orbits of Mars & Jupiter and leftovers from the early formation of our solar system
What is Maria similar too?
Maria are similar to our ocean floor basins
Which planet are humans trying to explore and potentially live at in the near future?
Mars
Order of Planets (Closest to the Sun to farthest from the Sun)
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto
Difference between meteoroids, meteors and meteorites
Meteoroids: Rocky fragments moving through space Meteors: Meteoroids that burn-up in our atmosphere Meteorites: Meteors that contact Earth's surface
What is a Solar Eclipse?
Moon blocking the suns light
Meteor Showers
Occur anytime Earth passes through the remains of a Comet's dust trail
What is the penumbra?
Partial shadow
Perigee vs Apogee
Perigee is when the moon is closest to Earth vs Apogee is when moon is farthest from Earth
Perihelion vs. Aphelion
Perihelion is the point in orbit when Earth is closest to the Sun vs Aphelion is the point in orbit when Earth is furthest from the Sun
Density of Saturn
Saturn is the only planet of the Solar System that is less dense than water—about 30% less.
Jovian (Outer Gas Giants) vs. Terrestrial (Inner Rocky Planets) Planets
The Jovian(Gas Giants) planets have Gaseous (H @ He), Large(low density), Slow Orbital Speed, Many moons & rings vs Terrestrial (Inner Rocky Planets) Planets have Solid, Rocky Surfaces, Small, Dense, Fast Orbital Speed, Few moons & no rings
Where is the Moon?
The average distance from the Earth to the Moon is 384,000 kilometers, or 238,000 miles
What is the umbra?
The darkest part of a shadow
Dinosaur extinction
The extinction of the Dinosaurs was caused by a 6-mile wide asteroid that hit in the Gulf of Mexico around 65 million years ago
Lunar Month
The time from New moon is 29.5 days
Period of Revolution
The time it takes for a planet to complete one full orbit around the Sun. Venus, Earth, Mars, Jupiter, Saturn, and Neptune have the longest than Mercury and Uranus which is the shortest
Period of Rotation
The time it takes for a planet to make one rotation around its axis. Mercury and Venus is the longest than Earth, Mars, Jupiter, Saturn, Uranus, and Neptune
Earth
Third planet from the sun
Waxing and Waning
Waxing is the term used when seeing more of the moon each night and Waning is term used when seeing less of the moon each night
Impact Craters
The result of an asteroid or meteorite impact with a planet's surface
Where does the Moon rise and set?
The moon follows the same path in the sky as the Sun, rising in the East and setting in the west and the moon rises and sets 50 minutes later each day
What is like on the Moon?
The moon has no atmosphere, no wind, no weather, and no erosion
Why is the Lunar month (29.5 days) longer than the moon's period of revolution (27.3 days)?
The moon must catch up to the Earth in its orbit around the Sun
Why do we see phases of the moon?
The moon revolves around the Earth, The moon reflects sunlight, Half (50%) of the moon's surface is always reflecting light, From Earth, we see different amounts of the Moon's lit surface, and also The phase of the moon depends on the positions of the Sun, Earth, and Moon
Why don't we see eclipses every month?
The moon's path around Earth is tilted compared to Earth's orbit around the sun.
How did the Moon form?
The most accepted theory for the moon's formation is called the Giant Impact Hypothesis and the Theia hit the Earth 4.5 billion years ago
