Halley's comet

By: Tanner and Emma

Halley's Comet is probably the most widely known comet out of over 4,000 comets in our solar system. Halley's comet was last visible from Earth in 1986, and it takes a little over 75 years for Halley's comet to complete its elliptical orbit around the sun. This means Halley's comet will not be visible again from Earth until 2061.

The center of Halley's Comet is made out of ice, so the temperature is very cold and ranges from about -50 to -100°C. Halley's Comet is about 10 miles long and 5 miles in diameter with a mass of 2.2x10¹⁴ kg and an average density of 0.6 g/cm³. Becasue of it's small size and mass compared to the Earth, Halley's Comet does not create much gravity and it does not have an atmosphere. Halley's Comet also has a very complex rotation because it has a irregular shape (like a peanut), and it takes between 2 to 7 earth days for it to rotate completely around.

Halley's orbit is elliptical in shape. The closest the comet gets to the sun is about 85 million miles (closer to the sun than Venus), or a little more than half the distance from the Earth to the sun. The furthest Halley's Comet travels from the sun is about 5.2 billion miles, or about the distance between Pluto and the sun. The closest Halley's Comet has ever come to Earth was 15 million miles in 1910.

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Looking at the graph above, Halley's Comet contains more Hydrogen and Oxygen than any other elements. Also, there is about twice as much Hydrogen in the comet as Oxygen. This makes sense because the nucleus of Halley's Comet is made mostly of ice (H₂O).


  1. What is the shape of the orbit of Halley's Comet?
  2. How long (years) does it take Halley's Comet to complete its orbit around the sun?
  3. What is the surface temperature of Halley's Comet?
  4. How far does Halley's Comet travel from the sun?
  5. When will we see Halley's Comet again and how old will you be?