About 35,000 years ago, when the first cave paintings appeared and the time of the Neanderthals was coming to an end, Comet Leonard was at aphelion (the point in its orbit farthest from the Sun), some 525 billion kilometers away (about 3,500 times the distance separating the Earth from the Sun).
This December, the comet’s long journey into the inner Solar System will have its closest approach to Earth, and it will be possible to observe it in the night sky. A once-in-a-human-lifetime event.
“The comet is in the early morning sky right at the moment, and that means getting up very early, probably around 5 a.m. or so and looking more or less to the northeast,” Ed Krupp, an astronomer and the director of the Griffith Observatory in Los Angeles, tells NPR.
For people in North America, the best time will probably be Monday morning when the comet will be near Arcturus, low on the horizon.
When and how could you see it?
Unless you live in Antarctica, Krupp said anyone on the planet can see the comet right now.
Until December 13, the comet will be visible in the morning sky with binoculars or a telescope. On December 12, it will be 21.7 million miles from Earth, the closest it will be to the planet.
“The comet will just be about half the width of a clenched fist to the left” of Arcturus, Krupp says. “You might spot it with the unaided eye, but more likely, you’re going to need binoculars [or] a telescope.”
The comet will appear next to the global star cluster Messier 3 on December 3.
On December 6, it will appear to the left of the star Arcturus, one of the brightest stars seen from Earth and a “bright orange star not to be missed.”
Beginning December 14, the comet will be visible in the night sky and, for a few days. No instruments will be needed to see it.
In the early hours of December 18, Leonard will be 2.6 million miles from Venus.