Comet Hale–Bopp
Comet · The Great Comet of 1997
Hale–Bopp was one of the most-watched comets in history. It was so big and bright that it could be seen even from city streets, and it stayed visible to the naked eye for about a year and a half – a record.
- ~60 km – huge for a cometNucleus
- ~18 monthsVisible by eye
- 1 April 1997Closest to Sun
Take a closer look
Spotted from afar
When Hale–Bopp was discovered in 1995, it was still out beyond the orbit of Jupiter – much farther away than comets are usually found. Being visible from so far away was the first clue that its icy nucleus was enormous, several times wider than Halley’s.
A secret third tail
Besides its famous dust and gas tails, Hale–Bopp had a faint third tail that nobody had seen on a comet before. It was made of sodium – the same element that makes old street lamps glow orange – and astronomers found it using special filters on their telescopes.
A tug from Jupiter
In 1996, on its way towards the Sun, Hale–Bopp passed fairly close to Jupiter. The giant planet’s gravity tugged on it and changed its path, shortening its trip around the Sun from more than 4,000 years to about 2,400. Planets can steer comets like this.
How we found out
- 1995
On the same night, 23 July, Alan Hale in New Mexico and Thomas Bopp in Arizona independently discover it.
- 1996–97
It becomes visible without a telescope and stays that way for about 18 months.
- 1997
It passes closest to the Sun on 1 April, showing off two bright tails.
- Today
It is heading back into the cold outer Solar System. Large telescopes still track it.
Why do some comets have two tails?
One tail is dust, pushed gently by sunlight into a curved, yellowish fan. The other is gas, blown straight back by the solar wind and glowing blue.
See it yourself
Not any more – it is far beyond Neptune, deep in the southern sky.
From the encyclopedia
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