One of the most distant active comets ever sighted is making its closest approach to Earth today, July 14, and you can follow the action live online.
comet (opens in new tab) C/2017 K2 (PANSTARRS), or K2 for short, is finally making its way to Earth after being first spotted in the outer reaches of the Solar System by the Panoramic Survey Telescope and Rapid Response System (PanSTARRS) in 2017. At the time, K2 was thought to be the am most distant active comet ever discovered, although surpassed by a distant megacomet named Comet Bernardinelli-Bernstein (opens in new tab) last year. K2 makes its closest approach (opens in new tab) to our planet on July 14, passing 168 million miles (270 million kilometers) from Earth (beyond the orbit of Mars).
Viewers can follow the comet’s passage online by tuning into the Virtual Telescope Project live webcast (opens in new tab)beginning at 18:15 (2215 GMT) on July 14. You can also watch on Space.com, courtesy of the Virtual Telescope Project.
Related: Massive, strange comet K2 is touring the solar system, surprising scientists in the process (opens in new tab)
Over the past five years, K2 has been steadily moving toward Earth. Composed mostly of frozen gases, rocks and dust, comets become active as they approach the Sun; The sun’s heat heats up the comet very quickly, converting its solid ice directly to gas (a process known as sublimation) and forming a cloud around the comet known as a coma.
Interestingly, K2 was already active when it was first spotted between the orbits of in 2017 Saturn (opens in new tab) and Uranus (opens in new tab)about 1.49 billion miles (2.4 billion km) from the sun, which by comparison is about 16 times farther from the sun than Earth is.
Initial observations showed that the comet had a large nucleus and a massive coma. While the Canada-France-Hawaii Telescope (CFHT) suggested that the core of K2 could be between 18 and 100 miles (30 to 160 km) wide, data from the Hubble Space Telescope (opens in new tab) pointed out that it could be as little as 18 km wide, EarthSky wrote.
Therefore, the comet’s impending approach provides a good opportunity for professional observatories to measure how big the nucleus really is.
The rest of us can focus on the beauty of the body passing by. Webcast viewers should expect to see a blurry patch of light representing the coma surrounding the comet’s nucleus.
While the comet continued on its way inner solar system (opens in new tab), it also got lighter. During its closest approach on July 14, the comet is expected to brighten to magnitude 8 or even 7, which unfortunately is still too faint to see with the naked eye, according to EarthSky.org. K2 will remain in the telescope’s field of view throughout the summer before heading to its closest approach to the Sun on December 19.
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