Moon, Comets, Meteors, & Asteroids!

AsteroidsAsteroids

What are asteroids?

a) The broken up remnants of a destroyed planet?

b) Material that never managed to form into a planet?

The current opinion thinks B, due to the existence of stable orbits between Mars and Jupiter.

An asteroid is a small, solid, rocky body that orbits close to the Sun. Most lie between Mars and Jupiter and have orbital periods of 3-6 years.

Irregular Orbits of Asteroids

• Asteroids have irregular shapes because their gravity is too weak to pull them into round shapes like the planets!

• There are more than 10,000 asteroids in the Asteroid Belt but they are far apart and together would be less mass than the Moon.

CometsComets

• Small body composed of chunks of rock and metal held together by ice (water, ammonia, methane, carbon dioxide)

• Anatomy of a comet– Coma: glowing “head” of the comet; as comet

approaches the sun, solar winds vaporize the frozen gases causing the nucleus to glow

– Tail: the solar wind that vaporizes the frozen gases also blows the gas away forming a long tail (millions of kilometers)

Comet’s Tail Points Away from the Sun

Some Comets

Meteors and Meteorites

Minor Members of the Solar System

Earth encounters particles all the time in space.

A meteorite is any portion of a space object that reaches Earth’s surface.

A meteor is the brief streak of light when a particle enters Earth’s atmosphere and burns up, popularly called a shooting star.

Major Meteor Showers

Lunar Motion

Lunar Rotation• The moon’s period of rotation about

its axis and its revolution around Earth are the same, 27 1/3 days.

• It causes the same lunar side to always face Earth.

Phases of the Moon

The phases of the moon are due to the amount of the moon that is lit by the sun.

These changes occur monthly (every 29 days, 12 hours, 44 min, 2.9 sec)

Phases of the Moon

animation

Eclipses

The Earth–Moon–Sun System

Solar eclipses occur when the moon moves in a line directly between Earth and the sun, casting a shadow on Earth.

Lunar eclipses occur when the moon passes through Earth’s shadow.

Solar Eclipse

Solar Eclipse

Lunar Eclipse

Lunar Eclipse

Lunar History

Origin of the Moon

The most widely accepted model for the origin of the moon is that when the solar system was forming, a body the size of Mars impacted Earth.

The resulting debris was ejected into space, began orbiting around Earth, and eventually united to form the moon.

Origin of the Moon

The Moon and Tides

• At the ocean, the moon’s gravity causes the water to rise and drop every 6 hours

• There are 2 high tides and 2 low tides daily