Small Bodies In The Universe Asteroids, Comets and Meteors Seasons for beatings

The orbit – the elliptical path of motion a body takes as it travels around another body in space Light year – the distance light can travel in a year (9.5 trillion km or 5.88 trillion miles / year - - that’s 12 “0”s!!!) Just for Interest: Light travels about 300,000 km (186,000 miles) per second The North Star is 431 light years from Earth Our nearest star, Proxima Centauri, is 4.28 light- years away

Rotation vs. Revolution rotation – the spinning motion of a body on its own axis (24 hr for Earth) revolution – the elliptical motion of a body as it orbits another body in space period of revolution – the time it takes to make one complete orbit, or revolution (roughly 365 days for Earth)

Quick quiz.... What causes us to have day and night? Is the rotation or the revolution of the Earth?

What About The Seasons? Seasons are caused by the tilt of the Earth

When it is summer in San Diego. County, the north pole of the When it is summer in San Diego County, the north pole of the Earth is tilted toward the sun. When it is winter in San Diego County,the north pole is tilted AWAY from the sun. Now let’s draw this. Turn back a page in your spiral (#19) and label it: “Reasons for the Seasons”

Asteroids asteroid – a small, rocky body that revolves around the sun asteroid belt – the region of the solar system most asteroids occupy; roughly between the orbits of Mars and Jupiter

Most of the asteroids have been named

Comets comet – a small body of ice and rock that gives off gas and dust in the form of a tail as it passes close to the sun; “dirty snowballs” Comets form in the outer regions past Pluto The tail is only visible near the sun and is due to the sun starting to melt the comet. Because of solar winds, the tail of a comet always faces away from the sun!!!

The tail of comet always faces away from the sun The tail of comet always faces away from the sun. This is due to solar wind.

Comet SOHO In The Constellation Orion

Comet Hyakutake over Arizona, 1996

Meteoroids meteoroid – a very small, rocky body that revolves around the sun and could potentially enter our atmosphere (In space) meteor – a streak of light caused when a meteoroid or comet dust burns up in the Earth’s atmosphere before it reaches the ground (If it burns up in our atmosphere) meteorite – a meteoroid that reaches the Earth’s surface without burning up completely (If it hits the ground)

Barringer Meteor (actually meteorite) Crater, Arizona

Look here for more crater information Geology.com Look here for more crater information