Five Things to Know About Comet ISON
Rare opportunity to view a comet in the daylight predicted
Comet ISON, which is expected to put on a show around Thanksgiving, is the most anticipated comet since Hale-Bopp more than 16 years ago.
As it makes its way closer to the Sun, accelerating every second, we may all get a chance to look at it, and it could put on a great show in November. In fact, some say it will be worthy of the title “Comet of the Century.” Here are five things you should know:
1. We’re already getting some good pictures of it, and it should only get better
Comet ISON, formally known as “C/2012 S1 (ISON)”, was discovered by Vitali Nevski of Belarus and Artyom Novichonok of Russia in September of 2012. Since its detection, ISON has been getting closer and closer to Earth, and as such, is getting easier to spot with the right equipment. Although it’s not visible to the naked eye, yet, most expect it to be – at least at dusk and dawn.
Here is an early picture of the comet as it approaches, from October:
— Nick Howes (@NickAstronomer) October 7, 2013
And here is another from November 18th:
— NASA Goddard Images (@NASA_GoddardPix) November 18, 2013
2. ISON is FAST
Ok, so we know Comet ISON is speeding along, but how fast is it really going? Well, during the month of October, on average, Comet ISON will travel more than 78,000 miles every hour, or 22 miles every second.
Think that sounds impressive? It is, but there’s more.
Consider this: the fastest speed a human being has ever reached was the crew of NASA’s Apollo 10 mission, which reached a top speed of 24,791 miles per hour.
In that context, 78,000 miles per hour sounds fast, but it’s not that fast.
When ISON makes its perihelion passage on Thanksgiving Day in the U.S. (when the comet comes closest to the Sun), the gravitational force will whip it around at close to 845,000 miles per hour (234 miles per second).
A graph to show Comet ISON's perihelion speed during November when it's predicted to reach an astonishing 845,000mph. pic.twitter.com/vyGHQ8Sj4y
— Comet ISON 2013 (@cometison2013) August 27, 2013
This video shows the speed in the upper-left corner increase. Remember, the comet is accelerating and will do so at an ever-increasing rate until it reaches the sun, which occurs at about the 1:37 mark in the video.
I recommend changing this video to 480p and viewing full screen:
Now that’s what I call fast!
3. It may be visible during the day
Some say ISON could provide us all with a rare celestial show.
As ISON closes whips around our Sun, the icy ball will quickly melt, ejecting gasses into space and creating a visible tail that could span as many as 70 degrees of arc in the sky. For reference, an adult human’s fist when extended at arm’s length covers about 10 degrees of arc. This translates to roughly 186,000 miles long, or one light-second.
While there is still much uncertainty, some say Comet ISON could rival the Great Comet of 1680 (remember that one?), as depicted below.
4. It'll be the only time we ever see it
It’s widely believed that Comet ISON has never been around these parts before. While many comets go around and around until they eventually die, some experts aren’t so sure that ISON will survive the trip around the Sun, but may rather burn up and disintegrate instead.
But don’t worry, there are always more comets that will show up in the future, and more are being discovered every year.
5. Everyone will be talking about it, and you can share your knowledge
Whether Comet ISON is truly the “Comet of the Century” or a true dud, as some project, people will start to talk about it more and more. It’s a fun event that, hopefully, will pan out and leave a lasting memory.
But even if it doesn’t, it’s a great way to get kids interested in science and the universe, which we’re learning more about every day.
Your Comet ISON Viewing Guide
Where to look:
Right now (October), Comet ISON is somewhere in the neighborhood of Mars. You may need a telescope to get a good view. You can also use some great, free smartphone apps like Google Sky Map for Android or Star Chart for iOS (which also has an in-app upgrade for spotting comets) to locate Mars and other objects in the night sky.
Throughout October and November, look for these objects in the sky to find the relative location of the comet. To make things easy, I've only listed night-sky objects that the apps above should find, however, you may need a a decent telescope or binoculars.
- October 16th: ISON passes roughty 2 degrees NNE of Regulus.
- October 26th: ISON appears within 3 degrees of the consetllation Leo.
- November 5th: ISON is moving on from Leo and on into the constellation Virgo.
- November 18th: ISON appears just north of the bright star Spica.
- November 22nd: ISON passes into the constellation Libra.
- November 23rd: ISON appears within a few degrees SSW of Merucury and Saturn.
As the comet continues, it gets closer and closer to the sun. This means that as we move the second half of November, the comet will be mostly visible around sunrise and sunset, right near where the sun is, at the horizon. The best viewing opportunities will likely be low in the east during early dawn.
If things pan out, ISON may even be bright enough to see in the sky during daylight, but remember not to look directly at the sun. It's important to remember, though, that at and near it's perihelion, ISON will be very close to the sun and for several days will be difficult and dangerous to spot Use sunglasses and an opaque object to block the sun itself if you intend to try and spot ISON during the day, but wait
Key viewing dates:
- October 18th, 2013: Full moon will wash out much of the night sky. Viewing conditions may be poor for a couple of weeks.
- November 1st, 2013: From this day on, ISON may be close enough to the Sun and bright enough for observers to find it with the naked eye.
- November 3rd, 2013: An annular-total solar eclipse occurs, giving people on the Atlantic coast of the U.S. and in Central Africa may provide an opportunity to view the comet during daylight for the first time (cross your fingers).
- November 17th, 2013: Full moon, which could dampen viewing opportunities. Being close to the perihelion, though, it may not diminish the view too much.
- November 28th, 2013: ISON’s perihelion occurs around 6pm Eastern/3pm Pacific. This will be its closest passage to the Sun, when it will whip around at over 840,000 miles per hour and come as close as 724,000 miles above the Sun’s surface (remember, Earth is 93 million miles from the Sun!)
- November 29th: Comet ISON may not survive the trip around the Sun, but if it does, a brilliant and long tail may be visible for weeks, if we’re lucky. However, for a few days, it will be too close to the sun for non-experts to view safely.
- November 30th & Beyond: During the days immediately following November 28th, ISON will be too close to the sun for most people to spot. Prime viewing opportunities of Comet ISON should be around December 10th-14th.
Here are a few other fun facts about ISON that you can share with others!
Comet ISON is estimated to be about 3 miles in diameter
When Comet ISON whips around the Sun, its surface temperature has been calculated to reach 2,700 °C (4,890 °F), hot enough to melt iron
Comet ISON provides no danger to earth, and will only get as close as about 40 million miles
Comet ISON will travel faster than 22 miles per second, on average, throughout October
Comet ISON will reach a maximum speed of about 845,000 miles/hour (234 miles/second)
The best time to view Comet ISON is expected around December 10-14
By chance that it does happen to be the “Comet of the Century”, you can now share your knowledge with others.