Near-Earth Asteroids: Zoom Astronomy

Advertisement.

EnchantedLearning.com is a user-supported site.
As a bonus, site members have access to a banner-ad-free version of the site, with print-friendly pages.
Click here to learn more.

(Already a member? Click here.)

Table of Contents

Enchanted Learning
All About Astronomy

Site Index

Our Solar System							Stars	Glossary	Printables, Worksheets, and Activities
The Sun	The Planets	The Moon	Asteroids	Kuiper Belt	Comets	Meteors	Stars	Astronomers	Printables, Worksheets, and Activities

ASTEROIDS

Introduction	Near-Earth Asteroids (NEA)	Asteroids and Dinosaurs	List of Some Asteroids	Composition	Activities, Web Links

Near-Earth Asteroids

NEAR-EARTH ASTEROIDS

Eros, Asteroid #433, is an elongated Near-Earth Asteroid which is 21 by 8 by 8 miles (33 by 13 by 13 kilometers). The density of Eros is 2.4 grams per cubic centimeter, roughly the same as the density of Earth's crust.

Asteroids whose orbits bring them within 1.3 AU (121 million miles/195 million kilometers) of the Sun are called Near-Earth Asteroids (NEA) or Earth-Approaching asteroids. These asteroids probably came from the main asteroid belt, but were jolted from the belt by collisions or by interactions with other objects' gravitational fields (primarily Jupiter).

About 250 NEAs have been found so far, but many, many more exist. The largest known NEA is 1036 Ganymede, with a diameter of 25.5 miles (41 kilometers). According to astronomers there are at least 1,000 NEA's whose diameter is greater than 0.6 miles (1 kilometer) and which could do catastrophic damage to the Earth. Even smaller NEA's could cause substantial destruction if they were to collide with the Earth.

There are three types of NEA's:

Amors (named for asteroid Amor, #1221): Asteroids which orbit between the orbits of Earth and Mars. Eros (#433) is an Amor.
Apollos (named for asteroid Apollo, #1862): Asteroids which cross Earth's orbit and have a period longer than 1 year. They have semimajor axes greater than 1 astronomical unit (AU), and perihelion distances less than 1.017 AU. Geographos is an Apollo.
Atens (named for asteroid Aten, #2062): Atens are asteroids that are always closer to the Sun than the Earth is; they have a period shorter than 1 year (the semi-major axis is smaller than Earth's). Ra-Shalom is an Aten.

Cruithne is an asteroid about 3 miles (5 kilometers) in diameter that is co-orbital with the Earth, which means that it shares roughly the same orbit as the Earth. It is a Near-Earth asteroid (NEA 3753). From the Earth, it appears to have a horseshoe-shaped orbit; it gets close to the Earth, then it moves away again. Its orbit is highly inclined to Earth's orbit. At its closest approach (which happens every 100,000 years), Cruithne comes to within 10 million miles (15 million km) of Earth (40 times the distance from the Earth to the Moon). Cruithne was named for the first Celtic tribal group that settled in the British Isles. Cruithne was discovered on October 10, 1986 by D. Waldron at Siding Spring Observatory, Coonabarabran, Australia.

Enchanted Learning^®
Over 35,000 Web Pages
Sample Pages for Prospective Subscribers, or click below

Overview of Site
What's New
Enchanted Learning Home
Monthly Activity Calendar
Books to Print
Site Index

K-3
Crafts
K-3 Themes
Little Explorers
Picture dictionary
PreK/K Activities
Rebus Rhymes
Stories

Writing
Cloze Activities
Essay Topics
Newspaper
Writing Activities
Parts of Speech

Fiction
The Test of Time

Biology
Animal Printouts
Biology Label Printouts
Biomes
Birds
Butterflies
Dinosaurs
Food Chain
Human Anatomy
Mammals
Plants
Rainforests
Sharks
Whales

Physical Sciences: K-12
Astronomy
The Earth
Geology
Hurricanes
Landforms
Oceans
Tsunami
Volcano

Languages
Dutch
French
German
Italian
Japanese (Romaji)
Portuguese
Spanish
Swedish

Geography/History
Explorers
Flags
Geography
Inventors
US History

Other Topics
Art and Artists
Calendars
College Finder
Crafts
Graphic Organizers
Label Me! Printouts
Math
Music
Word Wheels

Click to read our Privacy Policy

E-mail

Enchanted Learning Search

Search the Enchanted Learning website for:

Advertisement.

Advertisement.