How to watch the giant comet fly past Earth soon?

Five years ago, the Hubble Space Telescope spotted a large comet at the furthest distance ever, as it approached the sun from far away between the orbits of Saturn and Uranus. Now that gigantic space snowball is making its closest pass to Earth within weeks.

Comet C/2017 K2 will be closest to us on July 14 during its current sweep through the inner solar system. Even at its closest point, however, it will still be farther from us than the average distance between Earth and Mars. This will likely make it difficult to see the comet without at least a small telescope, despite its considerable stature.

There is a significant amount of uncertainty at this point about how big the comet’s nucleus is, according to NASA Solar System Ambassador Eddie Irrizarry and Kelly Kizer Whitt in EarthSky, with several observations suggesting a range between 11 and 100 miles (18 and 161 kilometers) wide. That means C/2017 is somewhere between just legitimately large and one of the handful of largest comets discovered to date, such as Hale-Bopp and Bernardinelli-Bernstein.

The size of the comet’s tail, or coma, is equally massive and indistinct. Early observations suggest that the trail of dust and gases behind C/2017 K2 is somewhere between 81,000 and 500,000 miles (130,000 and 800,000 kilometers) wide. So somewhere between the latitude of one and six Jupiters — that’s a downright epic trail.

To see the comet for yourself, you can check out public online observatories like the Virtual Telescope Project, which are sure to host viewing parties at some point. You can also now get your hands on a telescope and start spotting objects with an app like Stellarium, which can also point your lenses in the right direction as the comet gets closer.

After passing us in July, C/2017 K2 continues to perihelion, the closest passage through the Sun, before returning to deep space. Comets tend to behave unpredictably the closer they get to the sun. It may suddenly become more active and bright, or it may fall apart and disappear completely from view.

Whatever happens, this visit will likely be our only chance to get acquainted with this comet. His orbit is so long that he won’t be back for a few million years.