1P/ Hally or Hally's Comet has a highly elliptical orbit to the Sun. At its closest,
it goes between Mercury and Venus. At its furthest, 1P/ Hally is roughly the distance
of Pluto.
Hally's Comet is the reason why we get the Eta Aquarids meteor shower in May and
the Orionids meteor shower in October. This is due to Hally's nucleus spraying ice and
rock into space as it passes into the inner solar system.
1P/ Hally is visible from earth every 75-76 years, and you don't even need a telescope
to see it.
On 13 March 1986 1P/ Hally was the first comet to be visted by a spacecraft. The ESA's
Giotto spacecraft got within 370 miles of its neucleus.
