The brightest comet of this year, 46P/Wirtanen, will make one of the 10 closest comet flybys of Earth in 70 years. You might even see it with the naked eye.
The comet hit its closest point to the Sun on Wednesday. So, the best time to watch the “Christmas comet” is Sunday night into Monday morning. At the time of closest approach, you can see the comet in the constellation Taurus close to the Pleiades. It will pass within 7 million miles of Earth, making it one of the closet comets in modern times.
“This will be the closest comet Wirtanen has come to Earth for centuries and the closest it will come to Earth for centuries,” said Paul Chodas, manager of the Center for Near-Earth Object Studies at NASA’s Jet Propulsion Laboratory in Pasadena, California. What’s more, Chodas said, “This could be one of the brightest comets in years, offering astronomers an important opportunity to study a comet up close with ground-based telescopes, both optical and radar.”
46P/Wirtanen is a bright, green celestial blob that orbits Earth every 5.5 years.
Astronomer Carl Wirtanen discovered the comet in 1948 at Lick Observatory on Mt. Hamilton in Santa Clara County, California. With a width of 0.7 miles (1.1 kilometers), 46P/Wirtanen orbits the Sun fairly quickly for a comet – once every 5.4 years – making it a short-period comet. (Long-period comets, on the other hand, have orbital periods greater than 200 years.)
The comet appears green in the above image because sunlight has ionized cyanogen and diatomic carbon molecules.
The bright comet was the initial target for the Rosetta lander. But due to a launch delay in 2003, the Rosetta team ultimately selected comet 67P/Churyumov–Gerasimenko instead.
The Virtual Telescope Project will stream views of the comet for people who have problems with light pollution.
Thumbnail image: Astronomers took this 120-second image of the comet in Dec. 2 by an iTelescope 50 mm refractor located at an observatory near Mayhill, New Mexico. The streak below the comet was produced by a rocket body (upper stage) passing through the telescope’s field of view during the exposure. Credit: NASA