And if you’re interested in looking back, here’s an archive to all the past Carnivals of Space. If you’ve got a space-related blog, you should really join the carnival. Just email an entry to [email protected], and the next host will link to it. It will help get awareness out there about your writing, help you meet others in the space community – and community is what blogging is all about. And if you really want to help out, sign up to be a host. Send an email to the above address.
A powerful X-class solar flare erupting on the sun on July 6, 2012 photographed by the Solar Dynamics Observers. Credit: NASA
Life has existed on Earth for billions of years, appearing shortly after the planet had cooled and liquid water became available.
From the first bacteria to the amazingly complex animals we see today, life has colonized every corner of our planet.
As you know, our Sun has a limited lifespan.
Over the next 5 billion years, it will burn the last of its hydrogen, bloat up as a red giant and consume Mercury and Venus.
This would be totally disastrous for local flora and fauna, but all life on the surface of the Earth will already be long gone.
In fact, we have less than a billion years to enjoy the surface of our planet before it becomes inhospitable.
Because our Sun… is heating up.
You can’t feel it over the course of a human lifetime, but over hundreds of millions of years, the amount of radiation pouring out of the Sun will grow.
This will heat the surface of our planet to the point that the oceans boil.
At the core of the Sun, the high temperatures and pressures convert hydrogen into helium. For every tonne of material the Sun converts, it shrinks a bit making the Sun denser, and a little hotter.
Over the course of the next billion years or so, the amount of energy the Earth receives from the Sun will increase by about 10%. Which doesn’t sound like much, but it means a greenhouse effect of epic proportions.
A TerraSAR-X stripmap image of icebergs.Whatever is left of the ice caps will melt, and the water itself will boil away, leaving the planet dry and parched. Water vapor is a powerful greenhouse gas, this will drive the temperatures even hotter.
Plate tectonics will shut down, and all the carbon will be stripped from the atmosphere.
It’ll be bad.
As temperatures rise, complex lifeforms will find life on Earth less hospitable. It will seem as if evolution is running in reverse, as plants and animals die off, leaving the invertebrates and eventually just microbial life.
This rise in temperature will be the end of life on the surface of Earth as we know it.
Still, there are reserves of water deep underground which will continue to protect microbial life for billions of years.
Perhaps they’ll experience that final baking when the Sun does reach the end of its life.
Even a few hundred million years is an incomprehensible amount of time compared to the age of our civilization.
If humanity does survive well into the future, is there anything we could do about this problem?
As the Sun heats up, making Earth inhospitable, it heats up the rest of the Solar System too. Frozen worlds in the Solar System will melt, becoming more habitable.
Encaladus, a moon of Saturn, as shown in this Voyager 1 image. Credit: NASAIt’s possible that future civilizations could relocate to the asteroid belt, or the moons of Saturn. We could try something even more radical: move the Earth.
By carefully steering asteroids so they barely miss us, an advanced civilization could distort the Earth’s orbit, relocating our planet further from the Sun.
As the Sun heats up, our planet would be continuously repositioned so the surface temperature stays roughly the same. Of course, this would be tricky business. Make the wrong move, and you’re facing the frigid cold of the outer Solar System.
So there’s no need to panic. Life here has a few hundred million years left; a billion, tops. But if we want to continue on for billions of years, we’ll want to add solar heating to our growing list of big problems.
A new app called “Sky Live” was just released from Vito Technologies and it will save you countless planning hours in your stargazing agendas. Vito Technologies, through a super-secret process, has discovered a way to give users a sky watching forecast anywhere in the world for up to 7 days in advance.
Were you planning a camping trip to watch the Perseid Meteor Shower? Is Venus going to be in the perfect spot in the sky to pull out your telescope and have a sky watching party? Sky watching is heavily dependant upon weather conditions and all that careful party planning is out the window when a bank of clouds settles in.
Universe Today and Vito Technologies is giving away 10 free copies of this app. How do you enter your name for this “appy” goodness?
In order to be entered into the giveaway drawing, just put your email address into the box at the bottom of this post (where it says “Enter the Giveaway”) before Monday, October 7, 2013. We’ll send you a confirmation email, so you’ll need to click that to be entered into the drawing.
More info on this app from the Publisher:
What it does: The main screen gives you one number: let’s say 78%.
Same as Fahrenheit degrees in weather, this percentage gives you at-a-glance info on how good tonight is for stargazing. The number is calculated with a special formula that takes into account things like is there anything interesting in the sky tonight, how cloudy, how bright is the Moon, etc.
Why it is different:
The formula for our Stargazing Index is superbly original and highly confidential. Combined with stunning space images, we hope this will be the most beautiful and accurate stargazing forecast on the AppStore.
Highlights:
– New app from the developers of Apple Design Award winning stargazing app with over 7 mln users
– Designed specifically for iOS7 (but will work on everything starting with iOS 5): blur and parallax, stunning graphics
– Detailed info on stargazing conditions for any location in the world for seven days ahead
– Moon phases
– Rise, set, culmination/azimuth for the most important objects: the Sun, the Moon, Mars, Venus, Jupiter, Saturn, and the International Space Station
– Cloudiness
– Weather forecast
– Light pollution
– The International Space Station position over the map
Who knew that destruction could be so informative? Only by smashing particles together with more and more energy, can we truly tease out the fundamental forces of nature. Join us to discover the different kinds of accelerators (both natural and artificial) and what questions they can help us answer.
We record Astronomy Cast as a live Google+ Hangout on Air every Monday at 12:00 pm Pacific / 3:00 pm Eastern. You can watch here on Universe Today or from the Astronomy Cast Google+ page.
Black holes are a spot in the universe where you won’t see the sun shine in, to paraphrase that 1960s rock-musical Hair. But speaking of “hair”, a group of scientists says these singularities may have matter (sometimes referred to as “hair”) that could affect how they appear.
This is a tangled concept to figure out (so to speak), so let’s unpack what the new study in Physical Review Letters means.
When black hole understanding was still in its infancy in the scientific literature, physicist John Wheeler wrote a phrase that is now famous among scientists in that field: “Black holes have no hair.” His phrase referred to how black holes are defined, which he believed came down to only two factors: their mass, and their angular momentum, or the rotation velocity of the hole. (Some sources also say electric charge was included as a third factor.)
Say you have a black hole that was created out of a huge star that imploded. Even though the star itself had distinctive properties, this theory says they would vanish in a black hole. So to take that to a generality, Wheeler’s phrase said all black holes are essentially the same.
Artist concept of matter swirling around a black hole. (NASA/Dana Berry/SkyWorks Digital)
This understanding of black holes dates back to 1963, arising back to a “clean” black hole model first published by Roy Kerr. The new study agrees that Kerr’s work from 50 years ago works with general relativity, a theory from Einstein that (in very simple terms) says the laws of nature are consistent throughout the universe. (More at this past Universe Today article.) As the theory pertains to black holes, strong sources of gravity bend space and time.
Kerr’s theory, however, does not agree with extensions of Einstein’s work, the scientists said. These extensions are known as scalar-tensor theories and there are several variations on this topic. The physics deals with the interactions between two different types of fields, scalar and tensor. Scalar fields, according to this Massachusetts Institute of Technology paper, assign values for every point of space observed. (Think a temperature map of Mars). Tensor fields measure these variables with relation to each other.
This artist’s impression shows the surroundings of the supermassive black hole at the heart of the active galaxy NGC 3783 in the southern constellation of Centaurus (The Centaur). Credit: ESO/M. Kornmesser
The science team included Thomas Sotiriou, a physicist at the International School for Advanced Studies in Italy.
His team, Sotiriou said in a statement, “focused on the matter that normally surrounds realistic black holes, those observed by astrophysicists. This matter forces the pure and simple black hole hypothesized by Kerr to develop a new ‘charge’ (the hair, as we call it) which anchors it to the surrounding matter, and probably to the entire universe.
“According to our calculations,” he added, “the growth of the black hole’s hair is accompanied by the emission of distinctive gravitational waves.”
The current brightest comet in the skies, Comet C/2012 V2 LINEAR, appears to pass by the bright spiral galaxy NGC 2997 in Antlia on September 29, 2013. Credit and copyright: Damian Peach.
Just in from the pretty pictures department: Award-winning Astrophotographer Damian Peach from the UK took this gorgeous image this morning of Comet C/2012 V2 LINEAR passing by bright spiral galaxy NGC 2997. While the cosmic duo looks like they are right next to each other, Damian notes that in reality, the comet is 17 light minutes away from Earth while NGC 2997 is 38 million light years away.
The specs: 0.11m F5.6 with STL-11k. LRGB. L: 5x3mins. RGB: 1x2mins.
Want to get your astrophoto featured on Universe Today? Join our Flickr group or send us your images by email (this means you’re giving us permission to post them). Please explain what’s in the picture, when you took it, the equipment you used, etc.
This week the Virtual Star Party crossed off one of the items on my bucket list: star trails. During the star party, Cory Schmitz kept the shutter going on his Canon 5D and took a series of images of the stars turning around the celestial North Pole. Once the timelapse was complete, we had a beautiful set of star trails, showing how much the Earth rotates during an hour.
The Upside Down AstronomerPaul Stewart jumped in with an amazing view of the Sun from New Zealand. We could see prominences and granules on the surface of the Sun, especially when he zoomed in.
And while all this was going on, we also got a chance to see beautiful clusters, nebulae and galaxies.
We hold the Virtual Star Party every Sunday night as a live Google+ Hangout on Air. You can find out more information from the Virtual Star Party. We start when it gets dark on the West Coast of North America.
The Cygnus cargo spacecraft is just a few feet away from the International Space Station's Canadarm2 during rendezvous and berthing on Sept 29, 2013. Credit: NASA
The Cygnus cargo spacecraft is just a few feet away from the International Space Station’s Canadarm2 during rendezvous and berthing on Sept 29, 2013. Credit: NASA
Updated – See Falcon 9 launch video below[/caption]
Today (Sept. 29) was a doubly historic day for private spaceflight! And a boon to NASA as well!
Early this morning the Orbital Sciences Cygnus commercial cargo ship docked at the International Space Station (ISS) speeding along some 250 miles (400 km) overhead in low Earth orbit.
Barely a few hours later the Next Generation commercial SpaceX Falcon 9 rocket soared to space on a demonstration test flight from the California coast carrying a Canadian satellite to an elliptical earth orbit.
These missions involved the dramatic maiden flights for both Cygnus and the upgraded Falcon 9.
And both were high stakes endeavors, with literally billions of dollars and the future of commercial spaceflight, as well as the ISS, on the line. Their significance cannot be overstated!
Falcon 9 lifts off from SpaceX’s pad at Vandenberg on Sept 29, 2013, carrying Canada’s CASSIOPE satellite to orbit. Credit: SpaceX
Both Cygnus and Falcon 9 were developed with seed money from NASA in a pair of public-private partnerships between NASA and Orbital Sciences and SpaceX under NASA’s COTS commercial transportation initiative aimed at fostering the development of America’s private space industry to deliver critical and essential supplies to the ISS.
The powerful new Falcon 9 will also be used to send cargo to the ISS.
America completely lost its capability to send humans and cargo to the ISS when NASA’s space shuttles were retired in 2011. Orbital Sciences and SpaceX were awarded NASA contracts worth over $3 Billion to restore the unmanned cargo resupply capability over 20 flights totally.
The Cygnus spacecraft put on a spectacular space ballet – and was no worse for the wear after its docking was delayed a week due to an easily fixed communications glitch.
The Cygnus commercial resupply craft is installed by the Canadarm2 to the Harmony node. Credit: NASA TV
Cygnus is a privately developed resupply vessel built by Orbital Sciences Corp and Thales Alenia Space that is a crucial railroad to orbit for keeping the massive orbital lab complex well stocked with everyday essentials and science experiments that are the purpose of the ISS.
Cygnus was grappled in free drift by Expedition 37 space station astronauts Luca Parmitano and Karen Nyberg at about 7 a.m. EDT Sunday morning.
The pair were working at two robotics work stations from inside the Cupola and Destiny modules. They used the stations 57 foot long Canadarm2 to snare Cygnus at a distance of about 30 feet (10 meters). They gradually motioned the arm closer.
Running a bit ahead of schedule they successfully berthed Cygnus at the earth facing port of the Harmony module by about 8:44 a.m. EDT.
Cygnus was launched to orbit on its inaugural flight on Sept. 18 atop Orbital’s commercial Antares rocket from NASA’s Wallops Flight Facility on the Eastern shore of Virginia.
Hatches to Cygnus will be opened on Monday, Sept. 30 after completing leak checks.
“Today, with the successful berthing of the Orbital Sciences Cygnus cargo module to the ISS, we have expanded America’s capability for reliably transporting cargo to low-Earth orbit, “ said NASA Admisistrator Charles Bolden in a statement.
“It is an historic milestone as this second commercial partner’s demonstration mission reaches the ISS, and I congratulate Orbital Sciences and the NASA team that worked alongside them to make it happen.”
“Orbital joins SpaceX in fulfilling the promise of American innovation to maintain America’s leadership in space. As commercial partners demonstrate their new systems for reaching the Station, we at NASA continue to focus on the technologies to reach an asteroid and Mars,” said Bolden.
Cygnus delivers about 1,300 pounds (589 kilograms) of cargo, including food, clothing, water, science experiments, spare parts and gear to the Expedition 37 crew.
The upgraded SpaceX Falcon 9 blasted off from Space Launch Complex 4 at Vandenberg Air Force Base in California at 9 a.m. PDT (12 p.m. EDT).
Here’s a video of the launch:
It successfully deployed Canada’s 1,060 pound (481 kg) Cascade, Smallsat, and Ionospheric Polar Explorer (CASSIOPE) weather satellite and several additional small satellites.
This powerful new version of the Falcon 9 dubbed v1.1 is powered by a cluster of nine of the new Merlin 1D engines that are about 50% more powerful compared to the standard Merlin 1C engines and can therefore boost a much heavier cargo load to the ISS and beyond.
The next generation Falcon 9 is a monster. It’s much taller than a standard Falcon 9 – some 22 stories vs. 13.
It could launch from Cape Canaveral as early as this Fall.
Learn more about Cygnus, Antares, SpaceX, Curiosity, Mars rovers, MAVEN, Orion, LADEE and more at Ken’s upcoming presentations
Oct 3: “Curiosity, MAVEN and the Search for Life on Mars – (3-D)”, STAR Astronomy Club, Brookdale Community College & Monmouth Museum, Lincroft, NJ, 8 PM
Oct 8: NASA’s Historic LADEE Lunar & Antares/Cygnus ISS Rocket Launches from Virginia”; Princeton University, Amateur Astronomers Assoc of Princeton (AAAP), Princeton, NJ, 8 PM
Antares rocket lifts off at 10:58 a.m. EDT Sept 18 with commercial Cygnus cargo resupply ship bound for the International Space Station (ISS) from Mid-Atlantic Regional Spaceport Pad-0A at NASA’s Wallops Flight Facility in Virginia. Credit: Ken Kremer (kenkremer.com)Antares and Cygnus streak to space and the ISS from NASA Wallops on Sept. 18, 2013. Credit: Ken Kremer (kenkremer.com)
Opportunity starts scaling Solander Point See the tilted terrain and rover tracks in this look-back mosaic view from Solander Point peering across the vast expanse of huge Endeavour Crater. Moasic assembled from navcam raw images taken on Sol 3431 (Sept.18, 2013). Credit: NASA/JPL/Cornell/Marco Di Lorenzo/Ken Kremer - kenkremer.com
Opportunity starts scaling Solander Point – her 1st mountain climbing goal
See the tilted terrain and rover tracks in this look-back mosaic view from Solander Point peering across the vast expanse of huge Endeavour Crater. Opportunity will ascend the mountain looking for clues indicative of a Martian habitable environment. This navcam camera mosaic was assembled from raw images taken on Sol 3431 (Sept.18, 2013). Credit: NASA/JPL/Cornell/Marco Di Lorenzo/Ken Kremer (kenkremer.com). See the complete panoramic view below[/caption]
NASA’s intrepid Opportunity rover has begun an exciting new phase in her epic journey – the ascent of Solander Point, the first mountain she will ever climb, after roving the Red Planet for nearly a decade. See the rovers tilted look-back view in our Sol 3431 mosaic above.
Furthermore, ground breaking discoveries providing new clues in search of the chemical ingredients required to sustain life are sure to follow as the rover investigates intriguing stratographic deposits distributed amongst Solander’s hills layers.
Why ? Because NASA’s powerful Mars Reconnaissance Orbiter (MRO) circling overhead has also recently succeeded in collecting “really interesting” new high resolution survey scans of Solander Point! Read my prior pre-survey account – here.
So says Ray Arvidson, the mission’s deputy principal scientific investigator, in an exclusive Opportunity news update to Universe Today. The new MRO data are crucial for targeting the rover’s driving in coming months.
After gaining approval from NASA, engineers successfully aimed the CRISM mineral mapping spectrometer aboard MRO at Solander Point and captured reams of new high resolution measurements that will inform the scientists about the mineralogical make up of Solander.
“CRISM data were collected,” Arvidson told Universe Today.
“They show really interesting spectral features in the [Endeavour Crater] rim materials.”
Opportunity starts scaling Solander Point – her 1st mountain climbing goal
See the tilted terrain and rover tracks in this look-back panoramic view from Solander Point peering across the vast expanse of huge Endeavour Crater. Opportunity will ascend the mountain looking for clues indicative of a Martian habitable environment. This navcam camera mosaic was assembled from raw images taken on Sol 3431 (Sept.18, 2013). Credit: NASA/JPL/Cornell/Marco Di Lorenzo/Ken Kremer (kenkremer.com).
Solander Point is an eroded ridge located along the western rim of huge Endeavour Crater where Opportunity is currently located.
“Opportunity is on the bench at the tip of Solander Point,” Ray Arvidson told Universe Today exclusively. Arvidson is the mission’s deputy principal scientific investigator from Washington University in St. Louis, Mo.
At the bench, the long lived rover has begun scaling Solander in search of science and life giving sun.
“The CRISM data are being discussed by the MER [Mars Exploration Rover] Team this week,” Arvidson told me.
And it will take some time to review and interpret the bountiful new spectral data and decide on a course of action.
“For the CRISM data analysis we will have the MER Team see the results and agree.”
Expect that analysis to take a “couple of weeks” said Arvidson.
The new CRISM survey from Mars orbit will vastly improve the spectral resolution – from 18 meters per pixel down to 5 meters per pixel.
Above is the Pancam panorama acquired on sol 3375 when Opportunity was still approaching Solander Point. On it I have plotted the subsequent drives along the east side of the point, and the location on the contact as of September 18. The approximate places where we need to be by later this fall are shown here for anyone following along. It’s a new unexplored land with new scenes. Caption and Credit: NASA/JPL/Larry Crumpler
Another important point about ‘Solander Point’ is that it also offers northerly tilted slopes that will maximize the power generation during Opportunity’s upcoming 6th Martian winter.
In order to survive those Antarctic like, ‘bone chilling” winter temperatures on the Red Planet and continue with her epic mission, the engineers must drive the rover so that the solar wings are pointed favorably towards the sun.
And don’t forget that winter’s last six full months – that’s twice as long on Mars as compared to Earth.
The daily solar power output has been declining as Mars southern hemisphere enters late fall.
In the above Navcam panorama acquired on mid-morning on September 18 (sol 3431), you can see the contact between the younger Burns Formation sulfate-rich sands on the right and the older rocks of Endeavour crater on the left. We will probably follow this contact for ways to the south before starting the climb next week. Caption and Credit: NASA/JPL/Larry Crumpler
After traversing several months across the crater floor from the Cape York rim segment to Solander, Opportunity arrived at the foothills of Solander Point.
Solander and Cape York are part of a long chain of eroded segments of the crater wall of Endeavour crater which spans a humongous 14 miles (22 kilometers) wide.
Solander Point may harbor deposits of phyllosilicate clay minerals – which form in neutral pH water – in a thick layer of rock stacks indicative of a past Martian habitable zone.
The science team is looking at the new CRISM measurements, hunting for signatures of phyllosilicate clay minerals and other minerals and features of interest.
“Opportunity is on the bench on the northwest side of the tip of Solander Point,” Arvidson explained.
Since pulling up to Solander, the robot has spent over a month investigating the bench surrounding the mountain to put it the entire alien Martian terrain in context for a better understanding of Mars geologic history over billions of years.
Eons ago, Mars was far warmer and wetter and more hospitable to life.
“The rover is finishing up work on defining the stratigraphy, structure, and composition of the bench materials.”
“We are working our way counterclockwise on the bench to reach the steep slopes associated with the Noachian outcrops that are part of the Endeavour rim,” Arvidson elaborated.
“Opportunity is slightly tipped to the north to catch the sun.”
“Probably this week we will direct the rover to head south along the western boundary between the bench and the rim materials, keeping on northerly tilts,” Arvidson told me.
How does the bench at Solander compare to other areas investigated at Endeavour crater, I asked.
“The Solander Bench looks like the bench we saw around Cape York and around Sutherland Point and Nobbys Head,” replied Arvidson.
Opportunity scans Solander Point from a slope at the northern tip as she circles around the surrounding bench. This navcam camera mosaic was assembled from raw images taken on Sol 3423 (Sept. 2013). Credit: NASA/JPL/Cornell/Marco Di Lorenzo/Ken Kremer
The rover recently investigated an outcrop target called ‘Poverty Bush’. She deployed her 3 foot long (1 meter) robotic arm and collected photos with the Microscopic Imager (MI) and collected several days of spectral measurements with the Alpha Particle X-ray Spectrometer (APXS).
Thereafter she resumed driving to the west/northwest around Solander.
“On September 13, Opportunity finally landed on the bed rock of Solander Point,” wrote Larry Crumpler, a science team member from the New Mexico Museum of Natural History & Science, in his latest field report about the MER mission.
“The terrain right here is awesome,” according to Crumpler.
“There are several geologic units that are overlapping here. And Opportunity is sitting on the contact.”
“On the east side of the contact are rocks maybe a billion years older than those on the west side of the contact. This sort of age progression is what geologists look for when trying to understand the past by reading the rocks.”
“Opportunity is allowing us for the first time to do not only fundamental geographic exploration, but it is enabling on the ground geologic study of past climatic history on Mars,” notes Crumpler.
Today marks Opportunity’s 3441st Sol or Martian Day roving Mars – for what was expected to be only a 90 Sol mission.
Traverse Map for NASA’s Opportunity rover from 2004 to 2013
This map shows the entire path the rover has driven during more than 9 years and over 3431 Sols, or Martian days, since landing inside Eagle Crater on Jan 24, 2004 to current location at foothills of Solander Point at the western rim of Endeavour Crater. Rover is now ascending Solander. Opportunity discovered clay minerals at Esperance – indicative of a habitable zone. Credit: NASA/JPL/Cornell/ASU/Marco Di Lorenzo/Ken Kremer
So far she has snapped over 184,500 amazing images on the first overland expedition across the Red Planet.
Her total odometry stands at over 23.82 miles (38.34 kilometers) since touchdown on Jan. 24, 2004 at Meridiani Planum.
Meanwhile on the opposite side of Mars, Opportunity’s younger sister rover Curiosity is trekking towards gigantic Mount Sharp and just discovered water altered pebbles at the intriguing ‘Darwin’ outcrop.
And NASA is in the final stages of processing of MAVEN, the agencies next orbiter, scheduled to blast off from Cape Canaveral on Nov.18 – see my upcoming up close article.
Learn more about Curiosity, Mars rovers, MAVEN, Orion, Cygnus, Antares, LADEE and more at Ken’s upcoming presentations
Oct 3: “Curiosity, MAVEN and the Search for Life on Mars – (3-D)”, STAR Astronomy Club, Brookdale Community College & Monmouth Museum, Lincroft, NJ, 8 PM
Oct 8: NASA’s Historic LADEE Lunar & Antares/Cygnus ISS Rocket Launches from Virginia”; Princeton University, Amateur Astronomers Assoc of Princeton (AAAP), Princeton, NJ, 8 PM
NASA’s MAVEN Mars orbiter, chief scientist Prof. Bruce Jakosky of CU-Boulder and Ken Kremer of Universe Today inside the cleanroom at the Kennedy Space Center on Sept. 27, 2013. MAVEN launches to Mars on Nov. 18, 2013 from Florida. Credit: Ken Kremer/kenkremer.com
Comet ISON, photographed with a 3-inch (80mm) telescope on this morning Sept. 28 shows a circular green coma and short dust tail pointing northwest. Click to enlarge. Credit: Michael Jaeger
As NASA and the European Space Agency prepare their remote photojournalists – Mars Express, Mars Reconnaissance Orbiter and the Curiosity and Opportunity rovers – to capture photos of Comet ISON’s flyby of Mars early next week, amateur astronomers continue to monitor and photograph the comet from backyard observatories across the blue Earth. Several recent color photos show ISON’s bright head or nucleus at the center of a puffy, green coma. Green’s a good omen – a sign the comet’s getting more active as it enters the realm of the inner solar system and sun’s embrace.
Another great photo of the “greening” of Comet ISON taken on Sept. 24 with a 17-inch (43-cm) telescope. Click to enlarge. Credit: Damian Peach
Sunlight beating down on the comet’s nucleus (core) vaporizes dust-impregnated ice to form a cloud or coma, a temporary atmosphere of water vapor, dust, carbon dioxide, ammonia and other gases. Once liberated , the tenuous haze of comet stuff rapidly expands into a huge spherical cloud centered on the nucleus. Comas are typically hundreds of thousands of miles across but are so rarified you could wave your hand through one and not feel a thing. The Great Comet of 1811 sported one some 864,000 miles (1.4 million km) across, nearly the same diameter as the sun!
Among the materials released by solar heating are cyanogenand diatomic carbon. Both are colorless gases that fluoresce a delicious candy-apple green when excited by energetic ultraviolet light in sunlight.
Sounds like a plan. Newspaper clipping from 1910.
Cyanogen smells pleasantly of almonds, but it’s a poisonous gas composed of one atom each of carbon and nitrogen. Diatomic carbon or C2 is equally unpleasant. It’s a strong, corrosive acid found not only in comets but also created as a vapor in high-energy electric arcs. But nature has a way of taking the most unlikely things and fashioning them into something beautiful. If you’re concerned about the effects of cometary gas and dust on people, rest easy. They’re spread too thinly to touch us here on Earth. That didn’t stop swindlers from selling “comet pills” and gas masks to protect the public from poisoning during the 1910 return of Halley’s Comet. Earth passed through the tail for six hours on May 19 that year. Amazingly, those who took the pills survived … as did everyone else.
Comet ISON’s location and approximate appearance on October 1 seen from the Curiosity Rover. ISON will pass only 6.7 million miles (10.8 million km) from Mars on Tuesday Oct. 1. Stellarium
While Comet ISON is still too faint for visual observers to discern its Caribbean glow, that will change as it beelines for the sun and brightens. If you could somehow wish yourself to Mars in the next few days, I suspect you’d easily see the green coma through a telescope. The comet – a naked eye object at magnitude 2.5-3 – glows low in the northern sky from the Curiosity rover’s vantage point 4.5 degrees south of the Martian equator.
Comet Hale-Bopp shows off its bright dust tail and fainter, blue ion tail in early spring 1997. Credit: Bob King
I’ve noticed that when a comet reaches about 7th magnitude, the green coloration becomes apparent in 8-inch (20 cm) and larger telescopes. Bright naked eye comets often display multiple subtle colors that change chameleon-like over time. Dust tails, formed when sunlight pushes dust particles downwind from the coma, glow pale yellow. Gusty solar winds sweep back molecules from the coma into a second “ion” tail that glows pale blue from jazzed up carbon monoxide ions fluorescing in solar UV.
One of the highlights of seeing Comet L4 PANSTARRS through a small telescope was its brilliant, pea-like false nucleus glowing yellow from sunlit dust. The real comet nucleus – the actual comet – lies within the false nucleus and hidden by dust. Drawing: Bob King
During close encounters with the sun, millions of pounds of dust per day boil off a comet’s nucleus, forming a small, intensely bright, yellow-orange disk in the center of the coma called a false nucleus. Earlier this year, when Comet C/2011 L4 PANSTARRS emerged into the evening sky after perihelion, not only was its yellow tail apparent to binocular users but the brilliant false nucleus glowed a lovely shade of lemon in small telescopes.
With ISON diving much closer to the sun than L4 PANSTARRS, expect a full color palette in the coming weeks. While it may not be easy being green for Sesame Street’s Kermit the Frog, comets do it with aplomb.
