Asteroids & Impact

2010

What is an asteroid?

• Small, rocky object orbiting the Sun among other planets.

• Commonly called planetoids because they are considerably smaller than actual

planets.

• Estimated amount of asteroids in our solar system –1,000,000 total

What are asteroids made of and how big are they?

• Fe and Ni

• Vary in size and shape, but can be up to 940 miles in diameter.

Who was the first to discover one?• Father Giuseppi Piazzi

• Ceres, largest asteroid (940 km dia.) and first to be

discovered.

• Discovered on January 1, 1801

• *Discoverers name their asteroids

Ceres: size comparison

What are some cool asteroids?

• Vesta- the brightest asteroid

• Ceres- largest

• Ida- potato shaped and has a moon named Dactyl

• Pholus-covered in red, possibly organic, material

• Trojan Asteroids- orbit Jupiter, one group in front, one group behind

Ida (35X15 miles) and Dactyl

Are there different types of asteroids?

Metal or M-class

Similar to a core of a planet; made up of 5- 50% Ni and Fe.

Types…2

S-class: silica/Stony-Iron

• Metal/igneous rock; similar to mantle of a planet

• Two types: medosiderite and pallasitePallasite has olivine crystals

Types…3

C-class: carbon

• Similar to crust of a planet; made of sand with Fe-Ni bits; grains are in irregular lumps called chondrules

• Achondrite: a chondrite that’s been reheated and lacks chondrules

Identify this asteroid:

Where can asteroids be found?

• Between Mars and Jupiter in the Asteroid Belt.

Radar image of view from 4179 Toutatis

(travels 70,000 mph, often crosses Earth’s path)

How was the belt found?

• Johann Bode and Johann Titus determined a law giving the approximate distance of the planets from the Sun in

1770.

• Not a true law of relationships

• Pattern was used to find a planet between Mars and Jupiter, but found

the asteroid belt.

What are Apollo Objects/NEO’s/PHA’s?

• Apollo Objects- about 40, all cross Earth’s orbit & have very elliptical orbits.

• Near Earth Objects- about 2,000 total which are greater than 1km in diameter

• PHA’s-Potentially Hazardous Asteroids

*Concerned about these impacting Earth

NEO Orbits

Trojan Asteroids orbit with

Jupiter (in green color)

“The blue area shows all near-Earth asteroids while the red area shows only large near-Earth asteroids. In this context, "large" is defined as an asteroid having an absolute magnitude (H) of 18.0 or brighter which roughly corresponds to diameters of 1 km or larger.”

Can I discover an asteroid?

• Unless you have access to the Hubble Telescope, LINEAR, Arecibo Radio

Telescope, or an extremely expensive telescope of your own, your chances are

slim.

What is LINEAR?

• LINEAR- Lincoln Near Earth Asteroid Research Project

• Detects asteroids; has ability to monitor and calculate future asteroid paths

• Helpful in case Earth might have to deflect any asteroids on a collision path

What is the Arecibo Radio Telescope?

• Radio telescope

• Uses radar to determine asteroid sizes, shapes and orbits

• Detect future impacts

• Can also map planets in our solar system

Arecibo Radio Telescope, PR

Is there a chance of future impact?

• http://neo.jpl.nasa.gov/neo/

• www.spaceweather.com

• There are numerous possibilities, but so far most of the NEO’s have come close enough without getting into Earth’s orbit If a large one were to enter Earth’s orbit, it would look like …

…this!

Or this!

How about this?

Any recent encounters?

• March 2002, 60 meter diameter asteroid came within 288,000 miles of Earth

• Wasn’t detected until 4 days later because it was coming from the direction of our Sun.

• June 2002, a 100-meter asteroid (2002MN) came within 75,000 miles—once again, undetected until 3 days later

*largest asteroid to approach that close

Spaceguard Survey

• The term is from an Arthur C. Clarke novel

• The goal is to discover 90% of the Near Earth Objects that are 1km diameter or more.

• Global efforts being made

• Deflection strategies also being planned

Interesting facts

• Every asteroid in the Asteroid Belt put together would amount to less mass than Earth’s Moon

• Vesta can be seen with the naked eye

• NEAR Shoemaker landed on asteroid Eros, after orbiting for a year