Download File

Asteroids, Comets, &
Meteors
Chapter 6

Minor planets
AKA “asteroids” – rocky objects in orbit
around the sun
 Usually not visible without telescope
 Largest is ½ the size of the moon

Discovery of Minor Planets
Many found by streak photography –
timed photos so their movement makes a
streak
 so small they look like stars in telescope

Ceres – largest, discovered in 1801
 Vesta – brightest


Most asteroids between orbits of Mars &
Jupiter in “main asteroid” belt

Naming asteroids

Given name and number (by order of
discovery) once orbit known
 Ex:

1 Ceres
Over 100,000 so given number of year
discovered, then 2 letter suffix AA to ZZ

Family


A group of minor planets with a similar orbit
Trojan asteroids
Family with similar orbit as Jupiter
 Same distance from Jupiter as from the sun

 One
group ahead and one group behind Jupiter

Apollo Asteroids
Family with closest orbit to earth
 Aphelion are >1ua, perihelions <1ua
 Icarus has closest approach to sun (2ua)
 Apollos tend to stay outside earth’s orbit


Aten family
Moving 200 mph, perihelion <1ua, aphelion
>1ua
 Tend to stay inside earth’s orbit
 Could collide with earth if earth’s gravity
stretched asteroid’s orbit
 Collisions unlikely (on different plane)


NEAT: Near Earth Asteroid Tracking
program

Detects objects over 1 km in diameter near
earth
Homework: SRQ 6A 1-7 &
Minor Planets Assignment