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Comets and Observing them

Comet C/2017 T2 PANSTARRS is in the sky this month. As a long-period comet, you won’t have another chance to see it, so catch a glimpse while you can! Here’s a short guide to comets and how best to observe them.

What is a comet?

Throughout history, comets have been given scientific and mystical importance in many different cultures. Many people saw them as omens, often bad ones, for the future, and allowed their appearance to influence their decisions. We now know that comets are actually big clumps of rock and ice, that orbit the Sun with highly elliptical orbits. When they get close to the Sun, some of the material burns up, forming a huge glowing aura and tail stretching out behind it. The tail can be millions of miles long!

Comets come in 2 types: short-period and long-period. Short period comets originate from the Kuiper Belt beyond Neptune, and take a few hundred years to orbit the Sun. Long period comets come from much further out in the Oort Cloud, and can take up to 30 million years to orbit the Sun. These comets are much harder to predict than short-period comets, as the latter have sometimes been observed before.

How to observe

Comet C/2017 T2 PANSTARRS has a period of half a million years, so is classed as a long-period comet. Discovered in 2017 close to Saturn, it has only now reached the inner solar system, where it will be visible from amateur telescopes. At the moment, it appears close to the celestial pole, which you can find by locating the North Star, passing into the constellation of Ursa Major on the 18th.

Labelled map of the stars near the north celestial pole, with an almost vertical red line representing the path of a comet.
The path of comet C/2017 T2 (PANSTARRS). Dates are in month/day format.

You will need a telescope or pair of binoculars to see this particular comet. Binoculars are particularly useful, as you can sweep over the target area of the sky. Look for a fuzzy patch – the comet will not appear in focus like a star or planet. A fainter object than about +10 magnitude will need a telescope, but this comet won’t fall below that until August. Bear in mind that a comet will appear to your eyes to be fainter than a star of the same magnitude, as the light is spread out over a larger area.

Happy comet hunting everyone!

Sources: NASA Solar System Exploration, Universe Today