Not Kidding – a Comet Is Making Its Closest Pass to Earth Since Its Discovery This April Fool’s Day


Watch it live!

An iconic comet will be zooming past Earth this weekend, just in time for April Fool’s Day. Which, admittedly, does sound a little suspicious, but we promise this is definitely not a prank.

Comet 41P/Tuttle-Giacobini-Kresak was first detected back in 1858, and circles the sun every 5.5 years. This year, it will be making the closest flyby of Earth since its discovery, allowing us to catch an unprecedented glimpse as it zooms past at a very safe distance of around 21.2 million km (13.2 million miles) away.

 That’s a distance of 0.14AU, or a little over a tenth of the distance between Earth and the Sun.

Northern Hemisphere stargazers with small telescopes and potentially even binoculars will have the chance to see the comet from dark vantage points between dusk and dawn from now until mid-April, when it will be passing across the stars of the constellations Ursa Major and Draco.

But on April 1, the viewing will be particularly good, with the comet at its closet point to Earth since its discovery more than 150 years ago.

If you’re more of a hobby skywatcher, are located in the Southern Hemisphere, or are struggling with bad weather, don’t worry, you can watch it live here via Slooh’s coverage from its telescopes on the Canary Islands, starting at Friday 31 March, 8.30pm EDT (Saturday 1 April, 00:30am UTC).

So what can you expect to see? Well, unlike the green comet that streaked past earlier this year, Comet 41P isn’t particularly dazzling.

Comet 41P, as it’s known for short, belongs to a group of comets known as Jupiter comets, which have been captured by Jupiter’s massive gravity, and are now in orbit between the Sun and the gas giant.

 It’s also not particularly large – usually it appears in the night sky as a diffuse blob of light, no brighter than 8th magnitude, which means it’s only as visible as Neptune in the night sky, and is roughly 50 times too faint to be seen with the naked eye.

Good binoculars or small telescopes will be needed to pick it out, as well as a dark, clear, moonless night.

But, this year could provide an exceptional opportunity – scientists are predicting that the comet could undergo a dramatic outburst in brightness as it approaches the Sun.

This happened back in May 1973, just before the comet arrived at perihelion – its closest point to the Sun.

Unexpectedly, the comet’s brightness surged by 10 magnitudes, which meant it became 10,000 times brighter over just a few days, making it visible to the naked eye.

“Nobody knows for sure why the comet abruptly flared in 1973, but careful scrutiny of recent approaches to the sun in 1995, 2001, and 2006 suggest that outbursts in brightness tend to occur around the time [the comet] is passing closest to the Sun,” explains astronomer Joe Rao, from New York’s Hayden Planetarium, for Space.com.

The good news is that this year, perihelion occurs on April 12, just a little over a week after it zooms past Earth, which means we could be in store for another brightening event.

How dramatic that will be, or if it’ll occur at all, is anyone’s guess.

Just in case, we’re going to be watching it from the comfort of our couches over at Slooh.

If nothing else, it’s a good excuse to escape all the craziness of the internet on April Fool’s Day with some much needed perspective about the vast scale of our Solar System, and all the fascinating objects that travel through it.

Happy skywatching!

Source: http://www.sciencealert.com

Ice On Comet Is As Old As The Solar System.


Which came first, the comet or the solar system? At least when it comes to the comet’s ice, the answer is that they both formed around the same time (around 4.6 billion years ago).

Comet 67P/Churyumov-Gerasimenko

In a paper published in The Astrophysical Journal Letters researchers announced that they had discovered that the ice on the surface of comet 67P/Churyumov-Gerasimenko formed at the same time as the solar system itself. The comet is currently being observed by the Rosetta spacecraft

The ice on the comet’s surface is crystalline, meaning the water molecules are arranged in a neat orderly pattern within the ice. This kind of pattern occurs when water is allowed to cool relatively slowly, like in the cooling nebula of an early solar system. The experts believe this ice formed somewhere between -378.4 degrees Fahrenheit and -369.4 degrees Fahrenheit.

The researchers made this discovery not by analyzing the ice on a molecular level, but by looking at the chemicals trapped inside the ice on the comet’s surface. The ice contained only a tiny amount of Argon, a much smaller amount that would be expected if the ice was amorphous, or had a disordered structure of molecules. If the ice was amorphous that might have meant that the comet’s ice formed outside of the solar system, in interstellar space

When and where to see comet Lovejoy


A once-in-a-lifetime opportunity to see the green Lovejoy comet as it will not return for another 8,000 years.

'Star of wonder' seen in East'Star of wonder' seen in East

The comet, which was discovered in August by Australian amateur astronomer Terry Lovejoy, is travelling around 15 miles per second and has been billed as one of the brightest comets in years.

It has already reached its closest point to the Earth, a distance of 44 million miles, but it will remain easy to spot for about the next two weeks.

Although this would technically make this a naked-eye object, its diffuse fuzziness means that most viewers, who live under light pollution, will still need binoculars.

It has been visible for the past few weeks will reach its brightest point of magnitude 4 on Wednesday night.

Stargazers will still be able to see C/2014 Q2, albeit at a dimmer level, in total for the first three weeks of January.

Where is best to catch a glimpse of the comet?

You need to be in a dark sky area to get the best view of the comet.

It can be found by looking to the right of Orion, about two hand widths below the “seven sisters” Pleiades star cluster.

Dark Sky Discovery has a map of areas with little light pollution for the best chance of spotting Comet Lovejoy over the coming weeks.

Below are various dark sky areas and reserves around the UK, which are popular with astronomers.

London: The WaterWorks Nature Reserve, between Clapton and Leyton Midland Road rail station. You can also head out of the city to Surrey or Kent, to reduce the likelihood of light pollution.

Manchester: Heaton Park is the largest municipal park in the city, covering 600 acres. It also contains an astronomy club.

Birmingham: Warley Woods is accessible by bus or car from the city. Those driving should take the A456 Hagley Road westbound from the centre.

Newcastle: Northumberland National Park is an internationally designated Dark Sky Park.

Cardiff: Brecon Beacons offers some of the darkest skies in the UK. For more information on the best areas within the National Park

Belfast: Oxford Island National Nature Reserve is around 25 miles from the city, located on the shores of Lough Neagh.

Edinburgh: Newbattle Abbey College, off the B703 Newbattle Road, is part of Dark Sky Scotland.

Why does Comet Lovejoy have a green glow?

The comet gets its eye-catching colour from two gases, cyanogen and diatomic carbon, which both glow green when sunlight passes through them.

Its green hue is produced by molecules of diatomic carbon in the coma that fluoresce under the Sun’s ultraviolet rays.

In contrast, the comet’s delicate gas tail is tinted blue thanks to fluorescing charged molecules of carbon monoxide.

View image on Twitter

UK team’s data bonanza from comet


UK Researchers received “rich” data from the Philae lander just before its power died.

 

LanderScientists peer through the glass at a monitor (below) showing Philae’s dwindling power levels
Philae dies

Scientists say they detected what might be complex carbon compounds on the surface of the comet the craft landed on two weeks ago.

The results are from the Ptolemy instrument, which is a miniaturised on-board laboratory.

The detection of carbon supports a view that comets may have brought key chemicals to Earth to kick-start life.

“Start Quote

Now we have some data and it’s: Wow! This is what scientists do this stuff for”

Prof Ian WrightOpen University

The team leader, Prof Ian Wright, told BBC News: “We can say with absolute certainty that we saw a very large signal of what are basically organic (carbon) compounds.

“There is a rich signal there. It is not simple. It is not like there are two compounds; there are clearly a lot of things there – a lot of peaks. Sometimes a complicated compound can give a lot of peaks.”

The “peaks” refer to the graph produced by the Ptolemy instrument of the different molecules it detected. The result is in line with initial observations made by a similar German-led instrument on Philae.

In an exclusive interview with BBC News, Prof Wright explained that Ptolemy had gathered huge amounts of scientific data. Normally a quiet, understated man, he was marginally better at containing his enthusiasm than his co-worker and wife, Prof Monica Grady, whojumped for and then wept with joy and relief when Philae landed.

Prof Wright told me: “I am as excited now as I was a couple of weeks ago. It’s tremendous!”

Ptolemy team
Tense moments as the Ptolemy team waits to see how much of data will be streamed back from Philae

“For years, I’ve been giving public lectures about what we plan to do. Now we have some data and it’s: Wow! This is what scientists do this stuff for.”

Much of the data gathered by Ptolemy was collected on the fly. Shortly after the Rosetta spacecraft was activated in January, Prof Wright and his team saw the opportunity to analyse the comet’s tail as the spacecraft approached.

“It is not something we had planned to do, but it became obvious that it was something we could do.”

The early data suggests that the composition of the gases changed as the spacecraft got closer to the comet.

Prof Wright also explained that Philae’s bouncy landing suited his experiment. Among Ptolemy’s capabilities is the ability to analyse gases and particles around it, and so it was pre-programmed to sniff its environment shortly after landing.

Pictures from Rosetta show that the first landing created a dust cloud, providing Ptolemy with a feast of data.

Philae
An heroic demise for the little lander. With its last ounce of strength, Philae sent back precious data

But Philae’s bouncy landing and eventual resting place in the shade meant that it would not be able to recharge its solar powered batteries. The Ptolemy team had a few hours to rethink its scientific programme and upload a much curtailed set of experiments to the instrument.

Fuelled by the drama of the landing, and feeling the weight of history on their shoulders, all the various Philae instrument teams spent the night feverishly working to make the best use of the precious few days of operating life that the lander had left.

The hardest moment for the Philae team was having to abandon plans to analyse material drilled from underneath the comet’s surface. Overall, programme managers deemed that there was only sufficient battery power to drill for one sample, rather than two as was originally planned. A collective decision was therefore made that any sample should be analysed by the German-led COSAC instrument – not Ptolemy.

67P Comet
Philae should tell us what comets are made from, and what happened at the dawn of the Solar System

It is unclear whether the drill successfully managed to get a sample to COSAC.

But mission planners did grant the UK team Philae’s last ounce of strength to operate Ptolemy’s oven, to heat up all the debris that had collected inside the instrument to 200C and analyse the gases that came off.

Prof Wright confirms that this experiment was successfully carried out and that the results could give an indication of the composition of the carbon and nitrogen on the comet. These results may in turn help piece together what happened in the early years of the Solar System when the planets were forming.

The team wishes that Ptolemy could have carried out its full mission, but Prof Wright says the group is delighted with the results it has obtained. It also has the optimistic possibility of Philae coming back to life in the weeks ahead as the comet moves closer to the Sun and lighting conditions improve at the landing site.

“If you ask me whether we have done all we could have done, the answer is ‘no’. But I remain optimistic that the thing may come back to life and we will get the chance to do those things,” he said.

First comet landing site to be revealed


The European Space Agency (ESA) has planned to reveal the site selected for the first landing of a comet this week.

Philae, a landing module weighing about 100 kg that is part of Rosetta (robotic space probe), will probably touch down on Nov 11 on the surface of Comet Churyumov-Gerasimenko, which the unmanned spacecraft has been orbiting and observing from a distance of less than 100 km since Aug 6.

The ESA announced Aug 25 the five possible landing sites, photos of which scientists were examining in detail for three weeks to work out the operating and orbital strategies needed to get the probe to each one.

To do that, Rosetta approached to about 50 km from the comet, which allowed scientists to “gather more detailed information about each site”, in particular high-definition photos of the comet’s rocky, dusty and uneven surface, temperature readings and pressure measurements of the density of the gas surrounding the nucleus.

The ESA on Monday will announce the prime landing site and a backup site, and discuss what the specific challenges are with each one, and also other scientific results acquired so far.

Authorities have warned that the landing manoeuvre will be “complicated” and could last several hours because of the relatively small mass — and corresponding very light gravity — of the comet, which looks something like a potato the size of a mountain.

Once the probe has landed and attached itself to the surface, it is expected that Philae will be able to deliver valuable information to scientists for a period of about four months.

The orbiting module will continue observing the evolution of the comet’s activity through the end of 2015.

Rosetta was launched in 2004, and, over the past 10 years, has travelled almost 6.4 billion km on its odyssey to try and obtain data relating to the solar system’s origin.

 

Comet Swarms Around Nearby Star Hint At Huge, Unseen Exoplanet (VIDEO, PHOTOS)


Astronomers have detected bizarre swarms of comets around a nearby star, icy bodies that may have been trapped by the powerful gravitational pull of a huge, undiscovered exoplanet.

An international team of scientists spotted an enormous belt of carbon monoxide (CO) gas in the disk of debris surrounding Beta Pictoris, a young star that lies 63 light-years from Earth. The source of the gas is probably comets, and lots of them; one large comet must be getting destroyed every five minutes to keep replenishing the CO, which is destroyed by starlight, researchers said. You can see a video description of the mystery planet around Beta Pictoris here.

The swarms are likely corralled by a big, Jupiter-like alien planet orbiting far from Beta Pictoris, which is already known to host one gas giant (known as Beta Pictoris b) much closer in.

mystery planet
The ALMA radio telescope image of carbon monoxide around the star Beta Pictoris (above) can be deprojected (below) to simulate a view looking down on the system, revealing the large concentration of gas in its outer reaches. For comparison, orbits within our solar system are shown for scale. Image released March 6, 2014.

“Detailed dynamical studies are now underway, but at the moment we think this shepherding planet would be around Saturn’s mass and positioned near the inner edge of the CO belt,” study co-author Mark Wyatt, from the University of Cambridge in England, said in a statement. “We think the Beta Pictoris comet swarms formed when the hypothetical planet migrated outward, sweeping icy bodies into resonant orbits.”

The astronomers used the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile to map out millimeter-wavelength light from dust and carbon monoxide in the disk around Beta Pictoris, which is just 20 million years old.

ALMA’s observations revealed a giant belt of CO totaling more than 200 million billion tons — about one-sixth the mass of Earth’s oceans, researchers said. Much of the gas is contained in a single cloud 8 billion miles (13 billion kilometers) from the star. (For comparison, Earth orbits the sun at an average distance of 93 million miles, or 150 million km).

But there may actually be two clouds — and therefore two comet swarms — at this distance, researchers said. Because ALMA viewed the Beta Pictoris system edge-on, a separate cloud on the other side of the star may have been missed.

Researchers favor the two-cloud scenario, which implies the existence of a bigexoplanet orbiting far from Beta Pictoris — perhaps 10 times farther away than Beta Pictoris b lies. This idea has a parallel in our own solar system: Jupiter has corralled the space rocks in the asteroid belt into two clumps, with one group leading and the other trailing as they cruise around the sun.

beta pictoris
The star Beta Pictoris (center) is located 63 light-years from Earth in the constellation Pictor, the Painter, and is about 12 million years old and 75-percent more massive than our sun. Image from the European Southern Observatory’s Digitized Sky Survey 2.

But the thinking changes if Beta Pictoris is determined to contain just a single comet swarm. In that case, the most likely explanation would be a mammoth smashup between two icy, Mars-size planets about 500,000 years ago, researchers said. Ongoing collisions among the fragments generated by this original crash could replenish the CO cloud.

The presence of CO around Beta Pictoris also suggests that the system may eventually become a good candidate to host life as we know it, researchers said.

“Carbon monoxide is just the beginning — there may be other more complex pre-organic molecules released from these icy bodies,” co-author Aki Roberge, of NASA’s Goddard Space Flight Center in Greenbelt, Md., said in a statement.

Comet ISON dies as it rounds the Sun.


Our star apparently destroyed this surprisingly fragile celestial visitor during their close encounter.
Time-lapse image of Comet ISON from SOHO
Comet ISON comes in from the bottom right and moves out toward the upper right, getting fainter and fainter, in this time-lapse image from the ESA/NASA Solar and Heliospheric Observatory. The image of the sun at the center is from NASA’s Solar Dynamics Observatory.
ESA/NASA/SOHO/SDO/GSFC
Comet ISON (4.5 billion B.C. – A.D. 2013) survived for more than 4.5 billion years in the frigid depths of the solar system, but it fizzled during its brief moment in the Sun on November 28. Through a combination of ISON’s delicate makeup, the Sun’s intense heat, and — most importantly — our star’s powerful tidal forces, the comet’s nucleus failed to survive its brush within 730,000 miles (1.16 million kilometers) of the Sun’s surface.As the comet approached perihelion (its least distance from the Sun) November 28, it continued to brighten at roughly the rate astronomers had predicted. Late on the evening of the 27th (in North America), ISON peaked at magnitude –2.0. Images from coronagraphs aboard both the Solar and Heliospheric Observatory (SOHO) and the Solar Terrestrial Relations Observatory (STEREO) showed the comet as a bright point of light trailed by one distinct dust tail and a narrow dust streamer.

But ISON started to fade even before its closest approach to the Sun. The Solar Dynamics Observatory (SDO), which is equipped with the best cameras for close-up observations of our star and its surroundings, failed to see the comet at perihelion. And once ISON had moved far enough beyond the Sun that it could reappear in SOHO’s coronagraphs, it was nowhere to be found.

As astronomers began to write their post-mortems, however, the unpredictable comet rose from the dead like the legendary Phoenix. Some 24 hours after perihelion, SOHO once again captured images of ISON showing a thin dusty tail and a diffuse central condensation that some interpreted as a small remnant of the comet’s nucleus. But the revival soon began to peter out — by late on November 29, the glow had faded to around 6th magnitude.

It appears that the show amateur astronomers were hoping ISON would produce once it emerged from the Sun’s glare in early December won’t take place. Most scientists think the nucleus has dissipated, and any remaining dust likely will be too faint to see through anything but large telescopes. Even though ISON’s saga seems over, astronomers will spend months poring over their observations of this one-of-a-kind visitor.

 

ISON’s Ghost: ‘Comet of the Century’ is Now Ex-Comet


Sad news, comet fans: ISON is no more. It’s a vaporized husk of its former self. A sublimated dirty snowball. Comet ISON is an ex-comet and this time it’s not playing.

This sad turn of events is brought to you by the joint NASA/ESA Solar and Heliospheric Observatory (SoHO)’s LASCO instrument that gives a wide-angle view of the sun’s atmosphere (pictured above). For the duration of Comet ISON’s close approach to our nearest star, LASCO has been carefully tracking the comet’s progress. After many heart-stopping hours post-perihelion on Nov. 28, space experts nearly gave up hope — ISON had vanished from LASCO’s view, apparently not surviving the sun’s extreme tidal forces and powerful radiation.

But then, just as the U.S. was recovering from Thanksgiving turkey and wine, ISON re-energized; a component of its roasted nucleus had survived the turmoil and was brightening.

Unfortunately, the brightening was short-lived. Despite a couple of days of hope, Comet ISON’s nucleus has all but disappeared, leaving a ghostly wisp of dust behind.

The “Comet of the Century” is now, officially, the Turkey of the Century.

“Among experts, a consensus is building that the comet broke apart shortly before perihelion (closest approach to the sun),” writes Tony Phillips, NASA astronomer and curator of Spaceweather.com.

Like the countless sungrazing comets that have come before it, ISON succumbed to the close solar pass. Although hopes were high that the comet would survive the plunge, no one really knew what ISON was going to do. As a “virgin” comet from the Oort Cloud (a hypothetical cloud of cometary objects approximately one light-year from the sun), this was ISON’s first visit to the inner solar system. With little information on the comet’s composition, cometary fragmentation was always a possibility.

All that remains of Comet ISON seems to be a fan-shaped debris field of small fragments of the once-mighty cometary nucleus, each shard frantically venting the remaining ices into space. Any hope of seeing a dazzling naked-eye comet just in time for Christmas is vaporizing faster than the sublimating ISON fragments that now litter interplanetary space.

Hubble Spots Odd Asteroid With Six Tails.


Silly asteroid, tails are for comets! Around five months ago, an asteroid called P/2013 P5 was seen to be kicking off dust, making it look like it had a tail like a comet. Use of more detailed imaging would show that the asteroid actually has an unprecedented six tails.

In August, researchers had noticed P/2013 P5, an asteroid with a nucleus 1400 feet (427 meters) long, looked somewhat blurred through the Panoramic Survey Telescope & Rapid Response System (Pan-STARRS). Traditionally, asteroids appear as a sharp point of light, and this anomaly piqued the curiosity of the researchers. They figured that it might have begun rotating extremely quickly, causing it to kick off some of its surface dust and look like a comet.

On September 10, the team used the Hubble Space Telescope to get more detailed images of the oddball asteroid. The results completely dumbfounded the researchers: the asteroid had six tails that jut out in all directions, like spokes on a bicycle wheel! Even more amazing was the fact that when the team looked at it again less than two weeks later, the tails looked completely different.

After extensive analysis, it was determined that the tails are most likely the byproducts from six different dust-ejection events that were pulled out like tails by solar radiation pressure. That pressure is also believed to be what caused the asteroid to begin spinning so quickly in the first place, in a phenomenon known as radiation torque. If an asteroid is spinning too fast, its small amount of gravity is not enough to hold itself together and the dust goes flying off. Because the dust pattern does not suggest that a lot of material was ejected from the asteroid at once, the researchers are currently discounting the idea that these tails are the products of a collision. The results were published in Astrophysical Journal Letters.

So far, only a small percentage of its mass has been sloughed off into the tails, but this could be the beginning of the end for the asteroid. Future analysis will show if the dust is being ejected around the asteroid’s equator, which will be the best evidence that the asteroid is in the process of a rotational breakup.

While this is the first six-tailed asteroid that has ever been documented, researchers are confident that if there is one, there are probably many more waiting to be discovered.

– See more at: http://www.iflscience.com/space/hubble-spots-odd-asteroid-six-tails#sthash.QARL11oh.dpuf

What Will Comet ISON Do?


plumer_cometison_tail.jpg.CROP.original-originalSOHO_ISON_orbit.jpg.CROP.original-original

Now that comet Pan-STARRS has started to move on after a showy appearance in the twilight skies, it’s time to turn our attention to the next comet that could turn out to be a show-stopper: C/2012 S1 (ISON), generally just called ISON.

The comet was discovered in September 2012 by the Russian observatory called International Scientific Optical Network—ISON—using only a 40 centimeter (16”) telescope. Like most comets, it’s a chunk of ice and rock a few kilometers across. As it nears the Sun the ice will turn directly into a gas, and it will shed dust to form a tail. As the dust and gas around it expand and reflect sunlight, the comet will get brighter, though exactly how bright is hard to say.

The basic stuff you want to know is this:

  • Its orbit is nearly a perfect parabola, meaning this is probably its first ever pass into the inner solar system.
  • It’s a Sun-grazer, meaning it’ll dip really close to the Sun before heading back out again.
  • It’s been pretty active, blowing out lots of material despite being over 700 million kilometers from the Sun.
  • That means it may get much brighter as it gets closer, and some estimates put it as easily outshining Venus! But it’s hard to predict.
  • We are in no danger from this comet, which never gets closer than about 60 million kilometers from Earth, but we may pass through its debris early next year, sparking a cool meteor shower.

So here’s the scoop.

Its orbit is nearly a perfect parabola, meaning this is probably its first ever pass into the inner solar system.

Objects orbit the Sun in different kinds of paths. A closed path like a circle or ellipse means the object will orbit the Sun essentially forever—think planet or asteroid. Comets, though, tend to have very elongated orbits. There are probably trillions of icy chunks orbiting the Sun way out past Neptune, hundreds of billions of kilometers out. They spend vast amounts of time out there, and sometimes, slooowwwlllllyyyy start to drop toward the Sun, speeding up as they fall in.

Comet orbits typically are incredibly elongated ellipses, so long they start to look more like parabolae. Mathematically, a parabola is what you get if the comet drops literally from infinity, but starting a couple of hundred billion kilometers out is close enough. ISON may in fact have an even more extreme type of orbit called hyperbolic, which means it may have gotten a bit of an extra kick from a planet like Jupiter, giving it a scosh more energy. If this is the case, it will pass through the inner solar system with so much velocity it will never come back. Ever. It’ll travel out into interstellar space, and wander the galaxy.

So that’s pretty cool. This also means the comet is a virgin, so to speak. That makes it more interesting, astronomically: Every time a comet gets near the Sun it dies a little bit, losing gas and dust to space. If this is ISON’s first pass, that means it has a full quiver of material to shed, so it could be pretty bright.

Not only that, on Nov. 28, when it reaches perihelion (its closest point to the Sun) it’ll practically skim the star’s surface at a distance of only 1.2 million km (700,000 miles), about three times the distance of the Moon from the Earth, for comparison. That’s amazingly close! From that distance the Sun will be nearly 100 times bigger than we see it from the Earth. For the comet, it’ll be like sticking its head in a 5000 degree oven.

It’ll probably survive—the close encounter will last a few days, not long enough to totally vaporize the comet—and at closest approach will be traveling at something like 600 kilometers per second. That’s well over a million miles per hour. If that doesn’t hurt your brain, think of it this way: That’s 0.2 percent the speed of light. Yowza.

For a brief time, that close to the Sun, it’ll blaze brightly, reflecting that dazzling light. But it doesn’t have to be close to be bright…

In January of 2013 NASA’s Swift satellite used its Ultraviolet and Optical Telescope (UVOT) to take a look at ISON. Frozen water in the comet is already turning into gas due to sunlight, and when it gets hit by solar UV the water breaks down into atomic hydrogen and hydroxyl (OH)*. Hydroxyl itself will then emit UV light, which Swift can see and use to estimate the amount of water in the comet.

Observations indicate that the comet is shedding about one kilogram (2.2 pounds) of water every second! That may sound like a lot, but a comet can have a lot of water. Estimates give the size of the comet as about three kilometers across, a bit smallish, but it still could have trillions of kilos of water inside. It’s good for a while.

It’s also blowing out a lot of dust, far more than water: about a ton per second. Mind you, at the time Swift was looking the comet was farther from the Sun than Jupiter! It’s cold out there, so the fact the comet is doing this at all is hinting at a pretty dynamic time coming soon.

That means it may get much brighter as it gets closer, and some estimates put it as easily outshining Venus! But it’s hard to predict.

Predicting how bright a comet will get is really hard. Sometimes they fizzle. That can happen if it slows blowing out material, for example. Comet Kohoutek in the 1970s is the poster child for this, never getting as bright as hoped.

ISON will get very close to the Sun, so it will certainly get bright then, but it’ll be so close it’ll be hard to see. In 2007 I saw comet McNaught at noon! But it was so close to the Sun it was really hard to do. Maybe we’ll get lucky this time, and ISON will do well. I’ve seen estimates that actually predict it could get as bright as the full Moon, but again you have to take those with a pretty good dose of NaCl.

One way or another it should start getting easy to see in small telescopes over the summer, and hopefully be naked-eye visible by fall.

We are in no danger from this comet, which never gets closer than about 60 million kilometers from Earth, but we may pass through its debris early next year, sparking a cool meteor shower.

It bugs me to have to say it, but given the fear-mongering I see all the time online, it behooves me to say clearly that this comet poses no threat to Earth. It never gets very close to us, and its orbit is nearly perpendicular to ours.

However, the Earth will pass through the path of the comet a few weeks after the comet goes by, and since it’s shedding material we may get plow through some debris. This happens all the time with comets, and we call those events meteor showers. Given this comet is new, we may get a nice shower. Or, we very simply may not. Time will tell.

Interestingly, Mars will get a closer pass from ISON. On Oct. 1, 2013, the comet will pass roughly 10 million km (six million miles) from Mars. That’s far enough that the gravity of the planet won’t do much, and still pretty much guarantees Mars won’t see any impacts from the debris cloud.

But it’ll be a nice warm-up for 2014, when the comet C/2013 A1 (Siding Springs) will pass a few tens of thousands of kilometers from the planet! I suspect JPL engineers will use the near pass of ISON to test systems on the spaceprobes orbiting (and on) Mars now, getting observations of ISON as it blows past. That will help them understand better what to do when Siding Springs passes. I still wo

I’ll note that ISON has a weirdish orbit, coming in from north of the Earth’s orbital plane, dipping briefly south, then popping back up north. That means those of us above the equator will have a pretty good view. I expect we’ll be getting lots of amazing pictures of it, and I’m hoping to be one of the folks taking them.

But that’s months from now. I just wanted to give you a heads-up now, since you’ll be hearing a lot more about this celestial visitor in the months to come. As time goes on I’ll have more info, including more detailed star charts so you can see it yourself (like the one above), and instructions on how to safely view it (I add the adverb since it will be brightest when it’s close to the Sun, so observing has to be done with care).

So stay tuned. There may be lots more to come(t).

watch the video of it’s path on youtube.URL : http://www.youtube.com/watch?feature=player_embedded&v=40wICUY5VmU

Source: http://www.slate.com/blogs