Ask Me Everything4

comets, morę than anyother person.

Few people see Halley’s Comet twice. American author MarkTwain didn’t

after its discoverer. It is named after the astronomer who predicted its return -Edmond Halley. The comet appears every 76 years.

240 BCE

The earliest-recognized appearance of the comet in Chinese astronomical diaries

1066

The comet hovers over the Battle of Hastings and is depicted in the Bayeux Tapestry

1301

The comet’s appearance this year is used as a model for Giotto di Bondone's depiction of the Star of Bethlehem in his Nativity fresco in the Arena Chapel, Padua, Italy

1682

Viewed by English astronomer Edmond Halley when on his honeymoon in Islington, London, he predicts that the comet will return in 1758

1910

The first photograph of the comet is taken. Earth passes through the cornefs taił, and many people worry needlessly

Great Comet, 1577

Danish astronomer Tycho Brahe showed that this comet was much farther away than the Moon, proving that comets were not part of Earth’s atmosphere.

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Great Comet, 1680

This comet was observed by Isaac Newton.

He calculated its orbit, something never before done for a comet.

in with Halley’s Comet in 1835.

' V/

1986 The Giotto spacecraft flies

mm

images its nucleus

Donati, 1858

This spectacular example was the first comet to be photographed, by English photographer William Usherwood.

and I expect to go out with it.’

The comet did appear in 1910, but Twain didn’t live to see it—

he died one month before.

In numbers

6.6 ft

(2 m) The average depth of the layer of materiał lost from the nucleus of Halley’s’ Comet as it passes the Sun

100

The average number of hours that pass between comet discoveries by a dedicated comet hunter

230

The number of comets that return to Earth’s sky in periods of less than 200 years

3,400

The number of comets that return in periods greater than 200 years

62,137 miles

(100,000 km) The typical diameter of a cornefs coma

trillion

The minimum number of comets in the Oort Cloud

On target

In July 2005, the Deep Impact spacecraft fired a missile at Comet Tempel 1. The craft photographed the coUision, but the crater produced could not be seen through the huge cloud of very fine dust that formed. The Stardust craft will visit Tempel 1 in 2011 to observe changes in the comet sińce Deep Impact’s visit.

Idontl believe it ■

The nucleus of a comet is so fragile that you could puli it apart with your hands. When Comet Shoemaker-Levy 9 got too close to Jupiter in 1992, the planefs gravity pulled on it and the comet broke up into 20 pieces. These all hit Jupiter in 1994.

(c) 2011 Dorling Kindersley. All Rights Reserved.

Tempel-Tuttle,

1866

Observations of this comet and the Leonid meteors showed how comets decay to produce meteor showers.

Halley, 1986

| The first-ever image of a cometary nucleus (Halley’s) is taken by the Giotto spacecraft.

Wild 2, 2004

The Stardust spacecraft collected dust from the coma of Wild 2—the first materiał returned from a comet.

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