Have you heard about #Comet #46PWirtanen? It’s due to pass closest to the sun on December 12, 2018, and closest to Earth just a few days later, on December 16. Comet Wirtanen is the brightest comet in the night sky now; it’s the brightest comet of 2018. Although theoretically visible to the eye now, this comet is not easily visible to the eye. Astronomers have captured it using telescopes and binoculars (see a collection of photos here). It’s best seen from a dark location. To glimpse it, check to see if your local astronomy club will be hosting events for observing comet 46P/Wirtanen. Or visit the Virtual Telescope Project for a free, online viewing of comet Wirtanen on December 12 and 17.
As of early December, observers around the world are reporting that Comet 46P/Wirtanen is, in theory, bright enough to be seen with the eye. The problem is that the dim light reflected from the comet is spread over a large cometary atmosphere or coma.
So you’ll be looking for a large, diffuse, dim object.
The comet is moving in front of the stars from one night to the next. It appears in front of the same stars as seen from both the Northern Hemisphere and the Southern Hemisphere. But, as always, your orientation on these stars is different from different parts of Earth. Where should you look on any given date? See the charts below.
Or, try setting your specific location to this comet Wirtanen page at In-the-Sky.org.
You can also set your location at this site: TheSkyLive’s comet Wirtanen page.
Here’s another helpful article on how to see the comet, from SkyandTelescope.com.
The comet is still approaching, and so it is getting brighter. It should be brightest around December 16, when it will pass closest to Earth, within 7.4 million miles (12 million km). At that time, its visual magnitude should be around 3 (some are saying closer to 4, which would mean the comet is fainter).
If it the comet were a point source, like a star, it would be of medium brightness! But its diffuse coma and the nearly full moon on December 16 will make observations challenging.
This is a composite image, showing the size of comet Wirtanen’s coma – or extended atmosphere – in early December compared with the size of a full moon on our sky’s dome. The comet’s brightness is spread over this large area, and that’s why it’s so tough to see. Image via Brian D. Ottum (@astropicsdaily on Instagram).
If you do glimpse comet 46P/Wirtanen in December, here are a few details that might help you appreciate it.
Consider that the comet’s icy nucleus, or core, is less than a mile (just 1.2 km) wide. Meanwhile, its cometary atmosphere – or coma – is bigger, in an absolute sense, than the planet Jupiter.
When you see 46P/Wirtanen, consider the question of comet tails. Due to the orientation in space of Earth and Wirtanen when the comet is closest, the ion tail will be behind the comet, not visible from Earth’s perspective. So far, we haven’t seen much of a tail at all from this comet, but that could change. It might develop a slight curved tail in the coming days; if so, it’ll likely be easier to see in astrophotography than with the unaided eye.
Finally, if you are glimpsing the comet with optical aid, you might be able to discern this comet’s movement in front of the stars. Careful observations of the comet – in particular with a small telescope – should let you perceive its motion relative to the stars, over about a 30-minute period.
By Deborah Byrd and Eddie Irizarry
Comments
Post a Comment