Comet K2 will reach its closets point to Earth tomorrow

The mysterious comet was first discovered by the Panoramic Survey Telescope and Rapid Response System (PanSTARRS) in Hawaii in May 2017, and even at that distance, out between the orbits of Saturn and Uranus, it was emitting a powerful coma: a halo of gas that extended 80,000 miles (130,000 kilometers) into space.

Researchers speculate that K2 must have been active for several years when that first image was taken as backward modeling indicates that the comet was already venturing through space and oozing gas some 35 AU from the sun. AU refers to the Earth's average distance from the sun: one AU measures about 93 million miles (150 million kilometers).

What the scientists cannot understand is how the comet produced its coma. At the distances it has been traveling, the Sun's rays are not powerful enough to create such a halo.

"At 35 AU from the sun, temperature is probably something like 40 degrees above absolute zero," Jewitt said. "So we know that water is as solid as rock there. It couldn't be responsible for the activity that we saw at those large distances."

Despite its mysterious nature, Jewett believes that many comets must behave like K2; we just have not had the luxury of observing them.

"What makes this comet special is that it was discovered early," Jewitt said. "We've been able to follow the way the comet changes with distance from the Sun over a much larger range than has ever been done before."

Jewitt traces back the origins of K2 to the Oort Cloud, the repository of comets located a whopping 2,000 to 200,000 AU from the Sun. It was likely an unexpected gravitational kick originating from a star passing by the outer edges of the solar system that sent K2 on its incredible journey.

What other secret does K2 hold? Astronomers are bound to make some new observations tomorrow as the comet comes closest to Earth. We will be waiting impatiently to find out more about this marvelous oozing phenomenon.