Tempel 1
What is Tempel 1?
Comets· Nucleus ~6 km. The first comet that people deliberately hit with a spacecraft. NASA's Deep Impact struck its nucleus in 2005, and the Stardust spacecraft returned in 2011 to photograph the spot.
Orbit and period
| Nucleus | 7.6 × 4.9 km |
|---|---|
| Period | 5.58 yr |
| Distance | perihelion 1.77 AU (after the 2024 Jupiter pass) |
| Mission | Deep Impact strike 2005, Stardust revisit 2011 |
Figures are representative approximations. Source: compiled from NASA and IAU public data.
What Deep Impact revealed inside Tempel 1
When Deep Impact's impactor struck, a huge cloud of dust rose up. The grains were finer than a human hair. The cloud was so thick that the spacecraft could not see the crater the impact had made. The crater's shape was only seen six years later, when another spacecraft visited.
The nucleus turned out to have a density only about 0.6 times that of water. If its ice and rock dust were packed tightly, it would be much heavier, so the nucleus must be full of empty space. Tempel 1 is not a solid block but a loose heap of dust and ice. The dust thrown out contained silicates, carbonates, clay minerals and organic compounds.
For a while Tempel 1 was a lost comet. Jupiter's gravity changed its orbit, and it was not seen after 1879. In the 1960s Brian Marsden calculated a new orbit, which led to the comet being found again on a photograph taken in 1967. Since then it has been observed at every return, so its orbit became well known, which is why it could be chosen as Deep Impact's target.
The comet in depth
Comet Tempel 1 was discovered in 1867 by the German-born astronomer Ernst Tempel in Marseille, France. It travelled between about 1.5 and 4.7 AU from the Sun (after passing Jupiter in 2024 its closest approach widened to 1.77 AU) and goes around once every 5.58 years. Its nucleus is shaped like a potato, 7.6 km long and 4.9 km wide. Each time it passes near Jupiter, the giant planet's gravity changes its orbit a little.
On 4 July 2005 NASA's Deep Impact spacecraft released a 370 kg impactor, which hit the nucleus at about 37,000 km/h, roughly 40 times the speed of an airliner. It was the first experiment to dig into the inside of a comet. Far more fine dust shot up from the impact site than anyone had expected.
In February 2011 the Stardust-NExT spacecraft returned to Tempel 1 and found a crater about 150 m wide where the impactor had struck. It also saw that some parts of the surface had worn away as ice turned to gas during one trip around the Sun. In the orbit view you can see its short elliptical path between Mars and Jupiter.
Frequently asked
- How long is the orbital period of Tempel 1?
- The period of Tempel 1 is 5.58 yr.
- How far is Tempel 1 from Earth?
- The distance of Tempel 1 is perihelion 1.77 AU (after the 2024 Jupiter pass).
- In one line, what is Tempel 1?
- Comets — The first comet that people deliberately hit with a spacecraft.
Related
Figures are representative approximations. Simulated positions use J2000 mean elements.