The Solar System: Asteroids & Minor Planets

Find Your Inner Astronomer...

EQUIPMENT GUIDE

Telescopes
Types of Telescopes
Choosing a Telescope
Telescope Accessories
Spotting Scopes
Astrophotography

Astro Binoculars
Types of Binoculars
Choosing Binoculars
Binocular Accessories

< back to Solar System

Solar System: Asteroids or Minor Planets

Asteroids, also called minor planets, are small rocky bodies that are leftover material from the building of our solar system. Over 250,000 asteroids have been designated to date. Here are the 4 largest asteroids that can be viewed using telescopes:

Name	Diameter (km)	Mass (kg)	Rotation (hrs)	Orbit (yrs)	Type	Semimajor Axis (AU)	Eccen.	Inclin. (°)
Ceres	946	870,000	9.075	4.60	C	2.767	0.0789	10.58
Pallas	526	318,000	7.811	4.61	U	2.774	0.2299	34.84
Vesta	530	300,000	5.342	3.63	U	2.362	0.0895	7.14
Juno	240	20,000	7.210	4.36	S	2.669	0.2579	12.97

Types of Asteroids

There are three major types of asteroids:

C-type asteroids: Very dark,

S-type asteroids: Moderately bright,

M-type asteroids: Moderately bright,

Asteroid Groups

Asteroids are grouped according to their orbit range, as follows:

Near-Earth Asteroids Includes asteroids around 1.0 AU from earth and with perihelia less than or equal to 1.3 AU. These asteroids can be further grouped as follows:

Aten group: Innermost, semi-major axis less than 1.0 AU, perihelion greater than 0.983 AU.

Apollo group: Semi-major axis greater than 1.0 AU, perihelion less than 1.017 AU.

Amor group: Semi-major axis greater than 1.0 AU, perihelion between 1.017 and 1.3 AU.

Main Belt Asteroids Asteroids located between the orbits of Mars and Jupiter (1.8 to 4.0 AU) in the "asteroid belt".

Trojan Asteroids: Two groups of asteroids located along the orbital path of Jupiter, 60 degrees ahead and behind the planet.

Centaur Asteroids Asteroids located between Mars and beyond Neptune.

^ Top