Comet Tempel 1
The comet that Deep Impact struck with a 370-kilogram copper-tipped probe in 2005, to see what lay beneath the surface.
Key facts
- Designation
- 9P/Tempel
- Type
- Jupiter-family comet
- Orbital period
- about 5.6 years
- Closest to the Sun
- about 1.5 AU (about 225 million km)
- Farthest from the Sun
- about 4.7 AU
- Tilt of orbit
- about 11°
- Nucleus
- about 7.6 × 4.9 km
- Discovered
- by Wilhelm Tempel at Marseille on 3 April 1867
- Returns
- at perihelion in 2022; next in 2028
Orbit
Tempel 1 goes round the Sun every five and a half years, staying between the orbits of Mars and Jupiter. Close passes of Jupiter have changed its orbit several times, and after 1879 it was lost for almost a century until calculations allowed it to be found again in 1972.
Size and nature
The nucleus is about 7.6 km long, a tilted block with smooth terraces, cliffs and layered rock-like ground, suggesting it was built up in layers. It is very porous, with a density about half that of water.
History
Wilhelm Tempel, a German lithographer turned astronomer, found it from Marseille in 1867. It was one of the first short-period comets known.
Missions
The Deep Impact spacecraft released a 370 kg impactor, partly made of copper, which struck the comet at 10.3 km/s on 4 July 2005. The flash and the cloud of material thrown out were watched from the flyby spacecraft, from Earth and from space telescopes. The ejected cloud was mostly fine powder, not ice, and contained clays, carbonates and crystalline silicates: minerals that also appear in some meteorites and need either liquid water or high temperatures to form. The cloud hid the new crater. In February 2011 the Stardust spacecraft, on an extended mission, flew past and photographed it: a shallow scar about 150 m across, showing the surface is weak and loosely packed.
Space missions
- Deep Impact The mission that fired a copper projectile into a comet to see what lay beneath its crust.
- Stardust The first sample from a comet, and the surprise that it contained rock formed close to the Sun.
Key dates
| Date | What happened |
|---|---|
| 3 April 1867 | Wilhelm Tempel discovered the comet now known as Tempel 1. |
| 4 July 2005 | Deep Impact's probe struck Comet Tempel 1. |
| 14 February 2011 | Stardust flew past Tempel 1 and photographed the Deep Impact crater. |
Did you know?
The impact was timed for American Independence Day.
The impact changed the comet's orbit by an immeasurably tiny amount.
Tempel 1 was the first comet visited by two spacecraft at different times.