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