Sunday , June 20 2021

& # 39; Christmas Comet & # 39; 46P / Wirtanen and the meteor shower Geminids announce a week of crackers in the sky – Science News



Grab your cameras, flee the city lights and you'll have a front row seat for a beautiful sky show this week.

Key Points Comet Xmas

Key points

  • Comet 46P / Wirtanen will pass 11.5 million kilometers from Earth: the 10th closest comet gathering in 70 years
  • You will be able to see it through binoculars, or a standard DSLR camera that takes 15 seconds exposures, from anywhere in Australia
  • The comet will be bright at the same time as the Geminids meteor shower peaks – so you can take a great shot of both

The so-called "Christmas comet" – officially known as 46P / Wirtanen – is the brightest comet of the year. He will make his closest approach to Earth at the end of the night of December 16 (or early December 17 if you are in the AEDT time zone).

The comet is already visible if you have binoculars, and will be at its brightest point between December 14th and December 18According to amateur astronomer Ian Musgrave.

A day or so before, if you are willing to get up in the wee hours of the morning, you will also catch the meteor shower Geminids, which has a peak in the morning of December 15.

Comet 46P Wirtanen

Comet 46P Wirtanen

  • Discovered on January 17, 1948 by American astronomer Carl Wirtanen
  • Belongs to the Jupiter family of comets
  • Balance around the Sun every 5.4 years on average
  • This will be the closest and brightest approach for the next 20 years.
  • The Rosetta spacecraft was originally planned to study 46P / Wirtanen, but was postponed, eventually studying comet 67P / Churyumov-Gerasimenko.

Flying into a spot near Jupiter, the 46P / Wirtanen sways in the sun every five years or so, but it's usually too far for us to see.

This year it will pass about 11.5 million kilometers away – or 30 times the distance to the moon. Will not get this close again for another 20 years.

The comet, including its diffuse halo of light, is about the size of the full moon. At most, it will be the equivalent of the two weaker stars we can see in Cruzeiro do Sul.

But unlike the stars in the Southern Cross, "looks like a patch," so it's unlikely you can see it with the naked eye, Musgrave said.

The good news is that you should be able to see it through binoculars or using a standard DSLR camera if you are away from the city's bright lights.

"People are having good views on binoculars and should be potentially visible until early January," Musgrave said.

How to Identify the Christmas Comet

You can spot the comet from anywhere in Australia in the northeast sky about an hour and a half after sunset until the early morning when it sinks below the horizon.

"[Later in the week] It's best to start a little after midnight; so the crescent moon is setting and it's out of the way, "Musgrave explained.

The tricky thing with comets is that they move every night – for about a handspan – so you need to use the stars as landmarks.

Earlier this week, draw an imaginary line between Sirius, the brightest star in the sky, and Rigel, the bright blue star in the Orion constellation above the eastern horizon, and extend it to the next brightest star. span

In the middle of the week, the comet will be near the constellation of Taurus. Find the V-shape of the bull's head and look up toward two bright stars at the top of the constellation.

And until December 16, the comet will be between the red star Aldebaran and the star cluster of the Pleiades.

If you have a good view of the horizon, you can also catch a glimpse of Gemini's annual meteor shower at dawn in the morning.

Meteor shower geminids

Geminds meteor shower is the most reliable meteor shower in the southern hemisphere.

Most meteor showers are caused by dust and debris left over from passing comets, but the Geminids are the result of dust and debris from an asteroid called 3200 Phaethon, which is five kilometers wide.

You can see the shower from anywhere in Australia between December 13 and 16, arriving the morning of December 15.

To see it, you need to look for the constellation Gemini, about two palms above the horizon, below and to the right of Orion (or the pot).

"If you look north, the two brightest stars you see immediately above the horizon are Castor and Pollux and the radiant Geminids are immediately below that," Musgrave said.

Instead of looking directly at the radiant, the source point of all the meteors in the shower, scan the sky.

"If you look at the radiant, nothing will happen, because the meteors begin to burn next to where the radiant is," he said.

The best time to look is between 2:00 and 3:00 in the morning after the first quarter moon has passed.

And the further north you live the better, with the potential of a meteor every one or two minutes predicted under a dark sky.

"In the suburbs you'll see a little less, but you'll see a decent number of meteors," Musgrave said.

Locations by latitude December 13 December 14th December 15 (peak) December 16
Darwin 14 meteors / hour 31 meteors / hour 40 meteors / hour 9 meteors / hour
Brisbane / Perth 10 meteors / hour 21 meteors / hour 31 meteors / hour 7 meteors / hour
Sydney / Adelaide / Canberra 8 meteors / hour 17 meteors / hour 22 meteors / hour 5 meteors / hour
Melbourne 7 meteors / hour 15 meteors / hour 20 meteors / hour 5 meteors / hour
Hobart 5 meteors / hour 12 meteors / hour 16 meteors / hour 4 meteors / hour
* Between 2:00 AM and 3:00 AM (local time equivalent)

How to get good photos

Astrologer Dylan O'Neill took photos of 46P / Wirtanen (see above) earlier this month from his backyard in Byron Bay.

"The coma is particularly bright right now," said O & # 39; Donnell.

He also began to catch a tail of dust as it was expelled from the comet as it approached the sun.

Other astrophotographers also began to pick up a second tail, made up of gas particles ionized by the Sun's UV radiation.

Donnell used a specialized photographic telescope to capture the image in three minutes.

But, he said, you do not need high-end kit to take a photo of the comet.

All you need is a camera that can take a 15 second exposure with a wide lens and a tripod.

"Anyone with a DSLR camera and a large lens – 11mm, 16mm, even a fish eye – can just point the camera in the overall direction of the comet.

"Set it to a 15-second exposure, with the aperture as low as possible.

"And then set the ISO to 1600 or 3200 so that it looks good and loud, and you'll see a green spot on your images."

He said shooting comets can be tricky because they move.

"You take one photo and then another photo and another photo, so she's moving on the board," said O & # 39; Donnell.

"This allows you to make an animation if you take successive shots."

You will see the best images in the early evening when the comet is higher, far from the horizon.

But if you stay awake later to get the Geminids, let the exposure go, then it takes a succession of images.

"Then you can cheer them up later and watch all the meteors flying through the frame and choose any good Geminids in these frames," said Mr. O & # 39; Donnell.

A broad field view could even pick up another star named Mira in its brightest, most left of the comet in the constellation Cetus, Musgrave added.

"It must be a very good night," he said.

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