28-Nov

I debated about posting this when I first heard about it a while ago, but seeing as how it's made [semi]national astronomy news website, I figured what the fuck.



The incoming Comet ISON is now in the home stretch of its long-awaited hairpin loop around the sun on Thanksgiving Day (Nov. 28), making it a great target for amateur astronomers and stargazers. But there are some tips and info you'll want to keep in mind before you go comet hunting.

Comet ISON is on track for an extremely close shave of the sun when it flies by Earth's closest star on Nov. 28. The comet will approach within a mere 730,000 miles (1.2 million kilometers) of the sun during the encounter, leading many scientists and amateur astronomers to wonder if the comet will survive its Thanksgiving Day rendezvous with the sun.

In December, Comet ISON is expected to reach its greatest brilliance. It is during that month that it will be most interesting to both amateurs and the public.

Although forecasting the brightness of a comet months before its arrival at perihelion has always been hazardous, in the case of ISON until recently its brightening trend has been very difficult to decipher. Up until Nov. 13, the comet's increase in brightness was progressing at a rather sluggish pace, but then suddenly a noticeable outburst began taking place.

Comet ISON's brilliant flare-up

From Nov. 13 to 21, Comet ISON brightened by 3.5 magnitudes on the scale used to determine the brightness of objects in space. That's a 25-fold increase in brightness to the observer! Between Nov. 19 and 21 alone, ISON more than doubled in brightness. Along with this surge in activity, soaring rates of dust and gas were being released from its nucleus.

Amateur and professional astronomers around the world have been tracking Comet ISON in telescopes, with NASA spacecraft and other observatories tracking the object from space.

In the wake of this recent activity, experienced comet watchers are growing more confident that the comet has a chance to be ranked among one of the brightest in the last half century. "All this I regard as very promising for something quite significant to be seen from ISON come the early days of December," comet expert John Bortle said.

In fact, at its very brightest Comet ISON may even become briefly visible in broad daylight!

But just how impressive the comet will look after it sweeps around the sun will be strongly dependant on where you are located. From rural areas, where the night skies are still reasonably dark, the comet could evolve into a celestial showpiece — perhaps even a showstopper. Conversely, from major metropolitan areas under urban, light polluted skies, viewers will be largely disappointed.



Skirting above a solar furnace

Comet ISON's closest approach to the sun will mark the perihelion of its orbit around the star. That will occur on Nov. 28 at 1:38 p.m. EST (1838 GMT). During the encounter, the comet will rapidly approach the sun, and its brightness will likely increase sharply.

It is very difficult to say precisely just how bright Comet ISON will ultimately become when it passes nearly 730,000 miles of the 11,000-degrees Fahrenheit surface of the sun, while being subjected to enormous tidal and gravitation forces that could cause the comet to fracture into pieces. If this happens, it could release a tremendous amount of dust causing the comet to become many times brighter and unfurl a tremendously bright tail.

As the comet loops around the sun, and begins its return journey out of the inner solar system, it "may" be dimly visible in daylight by merely blocking out the sun with your hand. Soon after sunrise, ISON will be positioned within about 2 degrees to the right of the sun. During the rest of the day, the comet will appear to get closer to the sun, while rapidly moving in a clockwise fashion below and then to the sun's left. The comet will appear closest to the sun just before 2 p.m. EST (1900 GMT) when it will appear less than half the apparent width of the sun from the sun's limb, or edge. The comet's velocity as it whips in a hairpin turn around the sun will reach a maximum of 234.62 miles per second or 844,632 mph (1.3 million km/h)!

Soon after perihelion, perhaps on the mornings of Nov. 29 and/or 30, the ghostly dust tail might be visible low in the eastern sky, but the comet's brilliant head will still be embedded deep in the morning twilight.

Below is a look at Comet ISON's expected behavior in the coming weeks, given in 10-day intervals.

December 1-10: The changes in the comet wrought by perihelion passage become evident. Possibly the comet is brighter than expected during the first few days of this period. On Dec. 1, the tail could be as much as 12 degrees long (your clenched fist held at arm??s length measures roughly 10 degrees).

Because of ISON's close passage to the sun, the tail could appear very bright, while the comet's head might appear zero magnitude (as bright as the stars Vega or Capella), and perhaps brighter. Each morning the tail shoots out from the head like a narrow searchlight beam and will increase conspicuously in length as ISON backs into darker morning skies. The comet's head begins to rise before the onset of morning twilight — about 100 minutes before sunrise — on Dec. 6 and the tail length reaches to perhaps 20 degrees by Dec. 10. The comet's brightness by Dec. 10 should subside to between magnitude +3 (a star of medium brightness) and +5 (a faint star); the comet will have receded to 51.4 million miles (82.7 million kilometers) from the sun.

December 11-20:Comet ISON's altitude at the break of dawn increases from 13 degrees on Dec. 11 to 22 degrees on Dec. 15. The latter date will be the last morning in December that ISON can be viewed in a completely dark sky; the bright Moon that morning sets at 5:25 a.m. local time and twilight begins at 5:33 a.m. local time. So you will have just an eight-minute window of complete darkness. The full moon of December will occur on the following day.

But within a few days, attention will shift to evening visibility as the moon will be setting about an hour later each night while the comet begins to become increasingly evident low in the northwest sky after sunset. On Dec. 20, Comet ISON sets at 6:24 p.m. local time, 14 minutes after the end of evening twilight.

Meanwhile, the distance between the Earth and comet is rapidly decreasing to 42.5 million miles (68.3 million km) by Dec. 20. The comet will be in the constellation of Corona Borealis, the brightness of the head should hover somewhere between magnitude +4 (the brightness of a moderately faint star) and +6 (a very faint star at the threshold of naked-eye visibility). By this time, the ghostly tail may appear to reach 20 degrees to 30 degrees.

December 21-31: With the moon completely absent from the evening sky and Comet ISON climbing noticeably higher in the north-northwest sky with each passing evening, the full splendor of the comet is revealed. But again we stress — observers must get away from the bright lights of cities to view the comet in all its glory — seen against a dark backdrop it could be a sight not to be forgotten.

On Christmas Day, Comet SON has moved far enough northward in declination to become a circumpolar object; that is, it does not rise nor set but remains above the horizon all night long. The comet's closest approach to the Earth comes the following day: At 5:42 p.m. EST (2242 GMT), it will be 39,897,562 miles (64,208,902 km)away. The total light of the coma should continue to hold somewhere between magnitude +4 and +6. As seen against a very dark sky with the unaided eye, the comet's coma may appear half the diameter of the full moon. The gas tail should span many degrees, while the much brighter dust tail will continue to stretch toward the north for at least 20 degrees — even 40 degrees is possible.

January 1-10: The rest of Comet ISON's night sky display will seem anticlimactic, for the comet shrinks and fades rapidly now as it pulls away from both the sun and the Earth, with the magnitude dropping from perhaps +6 to +8 — below the threshold of naked-eye visibility even under a dark sky. The coma is expected to be quite large and diffuse, growing more so daily. Very straight and narrow, the tail initially should be traceable some 10 degrees to 15 degrees shortening to possibly down to 5 degrees by Dec. 10. The Great Comet is now only a ghost of its former self and is best seen in binoculars.

😕

Wow.

Thanks for posting this, HC.

Yea no kidding. I'll be watching.

Image of the solar corona, taken by the SECCHI inner Heliospheric Imager (HI-1)
on the STEREO Ahead observatory on November 26, 2013 at 09:18:01 UT/GMT.
This image was produced from the STEREO space weather beacon telemetry.
Because of the high amount of compression used for the space weather beacon,
the image quality is far lower than in the final science product.

Time can be measured in a number of ways. For instance, we can measure the passage of time via the orbital motion of Earth and other planets in the solar system (Dynamical Time). Or we can measure time based on the rotation of Earth on its axis with respect to the stars (Universal Time). Finally, we can measure time through the oscillations of atoms (International Atomic Time).

Universal Time or UT is the precise measure of time used as the basis for all civil time-keeping. Although their exact definitions differ, most readers can assume that Universal Time is equivalent to Greenwich Mean Time or GMT. Universal Time is actually based on the mean sidereal time as measured in Greenwich, England. It's also approximately equal to mean solar time from Greenwich.

Like most other astronomical calculations, eclipse predictions are usually presented in terms of Universal Time. In order to convert eclipse predictions from UT to local time, you need to know what time zone you are in. For North Americans, the conversion from UT to local time is as follows:

Atlantic Standard Time (AST) = UT - 4 hours
Eastern Standard Time (EST) = UT - 5 hours
Central Standard Time (CST) = UT - 6 hours
Mountain Standard Time (MST) = UT - 7 hours
Pacific Standard Time (PST) = UT - 8 hours

If Daylight Saving Time is in effect in the time zone, you must ADD one hour to the above standard times.

To translate UTC into your local time, use the following table:

United States
|Atlantic Daylight Time|>. subtract 3 hours from UTC|
|Atlantic Standard Time|>. subtract 4 hours from UTC|
|Eastern Daylight Time|>. subtract 4 hours from UTC|
|Eastern Standard Time|>. subtract 5 hours from UTC|
|Central Daylight Time|>. subtract 5 hours from UTC|
|Central Standard Time|>. subtract 6 hours from UTC|
|Mountain Daylight Time|>. subtract 6 hours from UTC|
|Mountain Standard Time|>. subtract 7 hours from UTC|
|Pacific Daylight Time|>. subtract 7 hours from UTC|
|Pacific Standard Time|>. subtract 8 hours from UTC|
|Alaska Daylight Time|>. subtract 8 hours from UTC|
|Alaska Standard Time|>. subtract 9 hours from UTC|
|Hawaii-Aleutian Standard Time|>. subtract 10 hours from UTC|
|Samoa Standard Time|>. subtract 11 hours from UTC|

Europe/Middle East
|Greenwich Mean Time|>. same as UTC|
|British Summer Time|>. add 1 hour to UTC|
|Central European Time|>. add 1 hour to UTC|
|Central European Summer Time|>. add 2 hours to UTC|
|Eastern European Time|>. add 2 hour to UTC|
|Eastern European Summer Time|>. add 3 hours to UTC|
|Charlie Time (Mid East)|>. add 3 hour to UTC|
|Delta Time (Mid East)|>. add 4 hour to UTC|

Australia
|Western Standard Time|>. add 8 hours to UTC|
|Western Summer Time|>. add 9 hours to UTC|
|Central Standard Time|>. add 9:30 hours to UTC|
|Central Summer Time|>. add 10:30 hours to UTC|
|Eastern Time|>. add 10 hours to UTC|
|Eastern Summer Time|>. add 11 hours to UTC|

its amazing how fucking nasa can't do their times right, fuck you Project Manager: Fred Espenak

http://www.worldtimezone.com/

Astronomers are anxiously waiting to see if a comet survives its encounter with the Sun.

Comet Ison will reach its closest approach to our star at approximately 1835 GMT on Thursday.

It has been billed as a potential "comet of the century", but the Sun's heat and gravitational tug could destroy it before it has a chance to light up the skies.

Some scientists believe it is already starting to buckle under the onslaught.

Prof Tim O'Brien, associate director of the UK's Jodrell Bank Observatory, said: "It's like throwing a snowball into fire: it's going to be tough for it to survive.

"But luckily, it's a big object and it moves fast, so it won't spend too much time close to the Sun. There is a lot of uncertainty."

Comet Ison came from the Oort Cloud, an mysterious, icy region at the furthest reaches of our Solar System.

It has been hurtling towards the Earth, travelling at more than a million kilometres an hour.

Now it is entering the most perilous stage of its epic journey.

It will pass the Sun at a distance of just 1.2 million km, effectively grazing its surface.

Professor Mark Bailey, from Armagh Observatory in Northern Ireland, said: "It's going to be exposed to the worst that the Sun can throw at it.

"It will be getting exposed to more and more intense solar heat, and that will start to sublimate the ices (turning them into gas) at an increasing rate."

The Sun's intense gravitational field produces tidal forces that will also have a major effect on the comet.

Scientists fear it could follow the path of Comet Lovejoy, which broke apart after it passed near the Sun in 2011. Or it could run out of fuel and fizzle out. Hopefully, Ison's large size could protect it.

Astronomers estimate that its nucleus could be several kilometres in diameter, helping it to withstand the solar assault.

If it does remain largely intact, the heat from the Sun will excite the dust and gas in its core, allowing it to blaze a trail across the night skies. But whether it really will be a "comet of the century" is unclear.

"If it survives, the best chance of seeing it will be in early December," explained Dr Robert Massey from the Royal Astronomical Society.

"I very much doubt Ison is going to be the sort of object where you go out in the morning, just before sunrise, and see this amazingly spectacular thing across the night sky.

"It's much more likely, at the optimistic end, that it's visible with the naked eye, and with binoculars - you could see the comet's head and a nice long tail coming from that."

There has been some debate already about whether Ison is starting to break up, and telescopes such as the Esa/Nasa Soho Sun-observing satellite will be trained on the star during the approach.

"There is a lot of uncertainty, but it's going to be exciting to watch," added Prof O'Brien.

http://www.bbc.co.uk/news/science-environment-25129711

well it looks like that shit broke up

The comet died?!!

Argghhh 😭

it only looks like a little piece made it out



its not like before

Ahh...it was a fascinating ride, while it lasted! 🙂

http://www.nasa.gov/content/goddard/comet-ison-fizzles-as-it-rounds-the-sun/index.html#.UpftdOJZWoY<BR>

Great thread! 🙂

Comet Ison, or some part of it, may have survived its encounter with the Sun, say scientists.

The giant ball of ice and dust was initially declared dead when it failed to re-emerge from behind the star with the expected brightness.

All that could be seen was a dull smudge in space telescope images - its nucleus and tail assumed destroyed.

But recent pictures have indicated a brightening of what may be a small fragment of the comet.

Astronomers admit to being surprised and delighted, but now caution that anything could happen in the coming hours and days.

This remnant of Ison could continue to brighten, or it could simply fizzle out altogether.

"We've been following this comet for a year now and all the way it has been surprising us and confusing us," said astrophysicist Karl Battams, who operates the US space agency-funded Sungrazing Comets Project.

"It's just typical that right at the end, when we said, 'yes, it has faded out, it's died, we've lost it in the Sun', that a couple of hours later it should pop right back up again," he told BBC News.

The European Space Agency, too, which had been among the first organisations to call the death of Ison, has had to re-assess the situation. A small part of the nucleus may be intact, its experts say.

Vaporised rapidly

How much of the once 2km-wide hunk of dirty ice could have survived is impossible to say.

Passing just 1.2 million km above the surface of the Sun would have severely disrupted Ison. Its ices would have vaporized rapidly in temperatures over 2,000C. And the immense gravity of the star would also have pulled and squeezed on the object as it tumbled end over end.

Karl Battams said: "We would like people to give us a couple of days, just to look at more images as they come from the spacecraft, and that will allow us to assess the brightness of the object that we're seeing now, and how that brightness changes.

"That will give us an idea of maybe what the object is composed of and what it might do in the coming days and weeks."

Whatever happens next, comets are going to be a big feature in the news over the next year.

In 11 months' time, Comet Siding Spring will breeze past Mars at a distance of little more than 100,000km. And then in November 2014, the European Space Agency's Rosetta mission will attempt to place a probe on the nucleus of Comet 67P/Churyumov-Gerasimenko.

fuck what a bitch it is to get on the soho site

lol, whoever claimed this comet was destroyed is probably kicking himself now. 😛

its going to take a few days while people with big telescopes and pricey satellites look at the surviving piece and in the meanwhile the media speculates. it was probably moving faster than its own gases could jet out or a teensy piece made it.

http://www.nbcnews.com/science/comet-isons-leftovers-fade-away-right-satellites-eyes-2D11674277<BR>

But the fading glow suggests that ISON is now little more than a dissipating cloud of cosmic dust in the solar wind. Late Friday, Battams estimated that the cloud's brightness was magnitude +5 and fading fast. If that trend holds, ISON's remnants won't be visible to the naked eye.