LPI-JSC Center for Lunar Science & Exploration2014 1

Impact on Asteroid?

P/2010 A2 dusty tail

Detected 6 Jan 2010 by LINEAR and classified as a comet.

Located in main asteroid belt (a = 2.290 AU, e = 0.1244, I = 5.25º).

120 m diameter “nucleus” & tail of mm-size dust particles.

Interpreted to be an asteroid that was hit by anotherasteroid a few meters in diameter

Jewitt et al. (2010)Snodgrass et al. (2010)

LPI-JSC Center for Lunar Science & Exploration2014 2

Disintegrating Asteroid?

P/2013 R3

Detected 15 Sept 2013 by Catalina Sky Survey and Pan STARRS; classified as a comet.

Occurs in main asteroid belt.

Composed of 10 objects.

The four largest fragments are up to 360 m in diameter.

Estimated mass of 200,000 tons.

Interpreted to be a weak asteroid that was spun up by sunlight until its rotation caused it to disintegrate. The fragments are separating at a speed of only 1 mph. (Jewitt et al.)

NASA Science News6 March 2014

LPI-JSC Center for Lunar Science & Exploration2014 3

Comets - What is in a name?

Naming conventions for survey-detected comets (revised in 2003)

• Prefix• P/ = periodic• C/ = non-periodic• X/ = comet without a reliable orbit• D/ = broken up or otherwise lost• A/ = object first thought to be a comet and later reclassified as an asteroid

• Year of discovery

• Followed by letter indicating half-month of discovery• A for first half of January• B for second half of January• C for first half of February, etc.

• & number indicating order of discovery

Thus, P/2010 A2 was classified as a periodic comet when it was discovered in the first half of January of 2010; it was the second comet of that period.

LPI-JSC Center for Lunar Science & Exploration2014 4

Asteroids - What is in a name?

Naming conventions for asteroids

• Provisional designation assigned when first observed• Composed of the year• A letter to indicate the half-month of discovery• A letter and subscript number to indicate sequential order of discovery

within that year; the subscript indicates how many times the alphabet has been cycled before the object was discovered. (I is not used, so each cycle has 25 letters rather than 26 letters)

• e.g., 1993 HH3 was discovered in 1993, in the first half of April; it was the (3 x 25) + 8 = 63rd minor planet in that period.

• Once enough data is calculated to define an orbit• A sequential number or designation is assigned• e.g., (8391)

• After a designation is assigned, the discoverer can propose a name

• e.g., The Spacewatch program proposed the name Kring, which was accepted by the IAU

• Final name: (8391) Kring = 1993 HH3