Universe Today

November 1, 2013December 23, 2015 by Nancy Atkinson

Announcing a New Comet ISON Photo Contest!

Universe Today is proud to announce that we are partnering with OPT Telescopes and SpaceWeather.com for a brand new Comet ISON Photo Contest, with over $10,000 in prizes to give away!

Comet ISON is one of the most anticipated sky events for years, and already astrophotographers have been busy trying to capture images of this comet. But as it gets closer to the Sun, hopefully it will become even brighter and visible to more people – not just the astrophotographers with the really great equipment!

This new photo contest features several different chances to win some great prizes, thanks to OPT Telescopes, the folks behind this contest. There will be a popular vote on Facebook with winners of first, second and third places, as well as images judged by a panel of experts with three winners in that category as well.

And so its not just about having great equipment. “It’s about the overall image and it can be in any ‘style’ at all,” says OPT Telescopes. “We’ve seen some amazing submissions shot with DSLR’s and point and shoot digital cameras in the past, and encourage everyone, regardless of skill level or equipment owned, to participate.”

Who can participate? Anyone aged 13 years and older who has a valid email address. (Employees of OPT, Universe Today and Spaceweather.com are not eligible for entry.) Images must be the original work of the contestant.

The contest begins today, November 1st, 2013 and ends midnight December 31st, 2013. Winners will be announced by January 7, 2014.

There are two ways to enter:

The first is through Facebook on this OPT Telescope page. Entrants are required to submit their date of birth, email address, real name and technical information about their image and location captured, as well as “liking” OPT Telescopes on Facebook.

Your image will become part of OPT’s Facebook gallery. One image, per day, per entrant is allowed.

If you’d rather not go through Facebook, you may submit via email to this address. Emailed entries are also required to list date of birth, and information about their image in regard to equipment used and location captured. All emailed submissions will be manually entered onto the OPT Facebook gallery to participate in the popular vote. Again, one image, per day, per entrant is allowed.

We also encourage those who enter to also upload their images to Universe Today’s Flickr Group page, so more people can see your images! We also feature many of the images uploaded there in our articles.

What are the prizes? As of November 1st, the prize donations are still rolling in! We now have over $10,000 in astronomy gear to give away to the winners of this contest. Final prize packages will be announced November 5th. So, stay tuned.

See this page for complete details and rules.

Good luck and we can’t wait to see all your images!!

November 1, 2013April 8, 2018 by Nancy Atkinson

Morning Comets Continue to Dazzle in New Images, Timelapses

Comet Lovejoy on November 2, 2013, as seen from Singapore. Credit and copyright: Justin Ng.

While many are anticipating seeing Comet ISON, there’s more in the sky these days than just one comet. There are actually four comets now in the skies in the mornings — in addition to ISON, there’s comets 2013 R1 Lovejoy, 2P/Encke and 2012 X1 LINEAR! Unfortunately, none of these are visible to the naked eye — yet anyway.

Here are some great recent images and video of these comet taken by amateur astrophotographers. Above is Comet Lovejoy, just taken by Justin Ng from Singapore . “Comet Lovejoy will share the same part of the sky as Comet ISON this month and it presents a cool astrophotography opportunity for skywatchers and astronomers,” Justin told Universe Today via email. “This image is a result of stacking 9 images together and each image was captured using a 3 inch telescope at 5 minutes exposure time for about an hour before dawn.”

Comet 2P/Encke on October 30, 2013. The coma is partially obscuring the small barred spiral galaxy NGC 4371. Credit and copyright: Damian Peach.

A gorgeous shot of Comet Encke by Damian Peach. “The fine narrow ion tail is very nicely defined which has recently developed,” Damian said via email.

Below is Damian’s image of Comet Lovejoy. “Looks as though a disconnection event may have occurred within Lovejoy’s gas tail,” Damian said. “Note the broad fan shaped condensation around half way along the tail.”

Comet 2013 R1 Lovejoy on Oct 31, 2013. Credit and copyright: Damian Peach.

Here are two great timelapses of Comet ISON! The first is from Justin Ng from Singapore, taken on October 27:

Journey of Comet ISON on 27 October 2013 from Justin Ng Photo on Vimeo.

And this one is from Maik Thomas/NOVAlapse Timelapse Recordings:

Short Animation of Comet ISON – C/2012 S1 from NOVALAPSE Timelapse Recordings on Vimeo.

A recent look at ISON from Efrain Morales with black & white matched with a negative view:

Comet ISON C/2012 S1 On October 31st, 09:17-34 UTC. Coma much denser now around the nucleus and possibly both tails (Ion,Dust) on negative image (lower right) 17 x 1 minute exposures. Credit and copyright: Efrain Morales/Jaicoa Observatory — Comet ISON C/2012 S1 On October 31st, 09:17-34 UTC. Coma much denser now around the nucleus and possibly both tails (Ion, Dust) on negative image (lower right) 17 x 1 minute exposures. Credit and copyright: Efrain Morales/Jaicoa Observatory

A nice shot of Comet Lovejoy nearby in the sky to the bright binary star system Procyon in Canus Minor:

Procyon and Comet Lovejoy in the morning sky on October 31, 2013, from Arizona. Credit and copyright: Robert Sparks.

If you want to try and see these comets for yourself (good astronomy equipment needed) check out our article on how to see these four morning comets.

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.

November 1, 2013December 23, 2015 by Nancy Atkinson

Best Halloween Costume Ever … IN SPACE!

Luca Parmitano dresses up for Halloween on the International Space Station. 'Lex Luthor's dream,' he tweeted.

This really happened, on the International Space Station, on Halloween. Awesome.

Follow Luca Parmitano on Twitter

November 1, 2013December 23, 2015 by Nancy Atkinson

Recent Sun Activity Spawns Stunning Aurorae

The auroral view while driving up Atigun Pass, North Slope Borough County, Alaska, US on November 1, 2013. Credit and copyright: Jason Ahrns.

Over the past several days the Sun has unleashed more than half a dozen major flares including four X-class events. The resulting aurora in some parts of the world have been beautiful. Here’s a collection of recent images taken by Jason Arhns in Alaska and one by Frank Olsen in Norway. In the image above, it seems the aurora is blanketing not only the sky, but the landscape as well!

See more below, as well as a video showing 23 of the 26 M- and X-class flares on the Sun between Oct. 23 and Oct. 28, 2013, as captured by NASA’s Solar Dynamics Observatory. It also shows the coronal mass ejections — great clouds of solar material bursting off the Sun into space — during that time as captured by the ESA/NASA Solar and Heliospheric Observatory.

Aurora seen over northern Norway on October 22, 2013. Credit and copyright: Frank Olsen.

You can see more of Frank’s beautiful imagery of aurora, the night sky and more at his Flickr page, his website (he has prints for sale) or his Facebook page.

Aurora over Sukakpak, Yukon-Koyukuk Census Area County, Alaska, US, November 1, 2013. Credit and copyright: Jason Ahrns.

A stunning green aurora almost covers the sky, but peeking through are the Pleiades and the Andromeda Galaxy. Credit and copyright: Jason Ahrns.

November 1, 2013December 23, 2015 by Dan Majaess

10-Year-Old Boy Discovers a 600 Million Year-Old Supernova

Canadian Nathan Gray (right) is likely the youngest person to discover a supernova. The supernova candidate (left) is probably located some 600 million light-years away (image from the ARO--Dave Lane). Follow-up observations will soon be acquired to confirm the supernova's class and nature.

Young Canadian Nathan Gray, age 10, has discovered a supernova candidate in the field of the galaxy designated PGC 61330, which lies in the constellation of Draco (the dragon).

Nathan made the discovery while scanning astronomical images taken by Dave Lane, who runs the Abbey Ridge Observatory (ARO) which is stationed in Nova Scotia. Incidentally, Nathan may unseat his older sister, Kathryn Aurora Gray, as the youngest supernova discoverer by a mere 33 days.

Nothing is visible at the location of the supernova candidate in prior images of the field taken over the past two years, or Digitized Palomar Sky Survey images.

Kathryn Aurora Gray garnered worldwide fame when she discovered a supernova in the galaxy designated UGC 3378 (see the Universe Today article by Nancy Atkinson). The discovery eventually earned her an audience with astronauts such as Neil Armstrong (shown below).

Kathryn Aurora Gray discovery of a supernova earned her the chance to meet Neil Armstrong, Bill Anders (Apollo 8), Victor Gorbakto, and Jim Lovell (Apollo 8 & 13). — Kathryn Aurora Gray’s discovery of a supernova earned her the chance to meet Neil Armstrong, Bill Anders (Apollo 8), Victor Gorbakto, and Jim Lovell (Apollo 8 & 13) (image credit: P. Gray/RASC).

Caroline Moore held the record prior to Kathryn as the youngest person to discover a supernova (Caroline was 14 at the time). Caroline subsequently had the honor of meeting President Obama at the White House (see the video below).

Supernova are immense explosions linked to the evolutionary end-state of certain stars. The explosions are so energetic that they can be observed in distant galaxies. Indeed, Nathan’s supernova could be some 600 million light years distant. Gazing into space affords humanity the opportunity to peer back in time. Despite the (finite) speed of light being a remarkable 300000 km/s, the light-rays must travel over “astronomical” distances.

There are several different classes of supernovae. For example, Type II supernovae are associated with larger mass stars. The Sun will not terminate as a supernova, but may potentially evolve into a standard (or not) planetary nebula (see the Universe Today post “Astronomers Hint that our Sun won’t Terminate as the Typical Planetary Nebula”).

Nathan’s discovery has been posted on the International Astronomical Union’s site, and its presence confirmed by US and Italian-based observers. Its provisional name is: PSN J18032459+7013306, and to get an official supernova designation a large telescope needs to confirm the unique supernova light signature (via a spectrum). Is the target a bona fide supernova?

“Given no motion, large distance from the galactic plane (ie. not likely a nova), and several optical confirmations, as well as its very close angular proximity to a faint galaxy, it is a supernova at any reasonable certainty,” said Lane, an astronomer in the Dept. of Astronomy & Physics at Saint Mary’s University, as well as the director of the Burke-Gaffney and Abbey Ridge astronomical observatories. “A significant fraction of
the supernova discoveries these days are not observed spectrographically due to the sheer number of them vs. telescope time.”

Nathan Gray is the son of Paul and Susan Gray.

*2013 10 31.9053 – update from the IAU: SN to be confirmed in PGC 61330 detected with 3 x 3 min images (exp 9 min). Astrometry: RA 18 03 24.12 Dec +70 13 26.4 (ref stars UCAC2) Photometry: 17.00CR +/-0.02 (USNO A2R Ref stars 163R, 170R, 172R, 173R). Measure on unfiltered image. Observer and measurer: Xavier Bros, ANYSLLUM OBSERVATORY, Ager, Spain. T-350mm f4.6. Link to image and further information: http://www.anysllum.com/PSN_PGC61330.jpg

November 1, 2013December 23, 2015 by David Dickinson

Watch Live: Sunday’s “Hybrid Solar Eclipse”

Totality! As seen during the November 13th, 2012 total solar eclipse. (Image credit: Narayan Mukkavilli, used with permission).

The chase is on. On Sunday, November 3^rd, the shadow of the Moon will cross the Earth for one last time in 2013. We recently wrote about the prospects for viewing this “hybrid” annular-total solar eclipse as it crosses the Atlantic and central Africa. Viewers from northern South America across the U.S. Eastern Seaboard up into the Canadian Maritimes will also be treated to a brilliant rising partial eclipse over the Atlantic at sunrise. Tickets are already in hand for many, as umbraphiles wing their way (cue Indiana Jones music) to dusty and exotic far off locales to stand briefly in the shadow of our Moon…

But what if it’s cloudy?

Once the bane of eclipse-chasers, you can now thwart our sometimes murky atmosphere by catching the solar eclipse online.

I remember our first experience with eclipse-chasing on the internet, trying to catch an eclipse broadcast on ye ole dial up modem from an internet café (remember internet cafes?) way back in the late 90s. This was pre-You Tube, pre-UStream. Needless to say, the tenuous connection afforded nary a frozen glimpse of the partially eclipsed Sun, and crashed all together at the onset of totality.

Fast forward to 2013, when ginormous data packets routinely fly around the globe.

True, this eclipse presents a challenge, as it crosses some pretty wild and unconnected terrain. But one standby that we can expect is the good people at Slooh, who have dispatched a broadcast team to the African nations of Gabon and Kenya:

As of this writing, Slooh looks to be going live at around 11:45 UT on Sunday November 3^rd. This is 6:45 AM EST, which takes into account our “falling back” one hour to UT -5 hours on Sunday morning. Astronomer Brian Cox will be broadcasting live from Kenya, and the broadcast starts just over two hours prior to the first landfall of totality at just before 14:00 UT. From Gabon, Maximum totality will be a brief 1 minute and 5 seconds, and will dwindle to an even briefer 14 seconds over Lake Turkana in Kenya before ending as a brilliant sunset eclipse over Somalia and Ethiopia. A backup broadcast of the partial phases of the eclipse is also planned from Slooh’s home base site in the Canary Islands.

Another fascinating potential broadcast may come our way from the BRCK organization basing their observations of the eclipse from the shores of Lake Turkana in Kenya. Billed as “Your Backup Generator for the Internet,” BRCK’s mission is to bring broadband access internet to people in remote regions of the world. This weekend’s eclipse certainly qualifies. As of writing this on Halloween, October 31^st, the BRCK team had gone into the field to “stress test” their webcasting capability onsite; follow them on Twitter as @brcknet for the latest updates. As of yet, there’s no embed for the broadcast, though we’ll be sure to drop it in if it surfaces!

There’s also some interesting science afoot during this eclipse as well. A recent press release out from Williams College notes that Field Memorial Professor of Astronomy and chair of the International Astronomical Union’s Working Group on Eclipses Jay Pasachoff will observe the eclipse, along with a student and tourist expedition from Gabon. A veteran eclipse chaser, Pasachoff will be working in concert with Dr. Vojtech Rusin of the Astronomical Institute of Slovakia, solar researchers Aris Voulgaris and Robert Lucas and William College students to study the ethereal solar corona. Satellite-based coronagraphs, such as the one employed by SOHO, can create an “artificial eclipse” of the Sun to study the corona, but also face the challenge of scattered light via a phenomenon known as Fresnel-diffraction. Pasachoff and team hope to combine their observations with those being routinely carried out by NASA, the European Space Agency and the Royal Observatory in Belgium to characterize the solar corona and improve our understanding of the space weather environment. Pasachoff’s expedition is being assisted via support from the South African Astronomical Observatory, Nommo Astronomia, the Gabon Astronomy Society and the Gabon Space Agency. Veteran eclipse chaser and historian Michael Zeiler (@EclipseMaps) has also joined up with Pasachoff’s group in Gabon.

In space, the NASA/JAXA joint solar observing Hinode spacecraft and ESA’s Sun watching Proba-2 will also catch several partial eclipses from their respective perches in low Earth orbit. Expect to see these pics in the days following Sunday’s eclipse.

We’ll be dropping in more broadcasts as they come to our attention this weekend here at Universe Today. Planning an ad-hoc webcast of the eclipse? Let us know in the comments below! Even if it’s just a brief view of the rising partially eclipsed Sun from the beach, its worth the effort. Just remember that you’ll need a fairly long focal length (in the range of 200mm or longer) and a proper solar filter for the Sun to appear like anything more than a washed out dot in the broadcast. And always run a test of your rig beforehand!

Good luck, happy eclipse chasing, and don’t forget to send those eclipse pics to Universe Today!

October 31, 2013December 23, 2015 by Elizabeth Howell

What Are The Odds Of Spotting A Milky Way Supernova From Earth?

Artist illustration of supernova. Credit: NASA

An exploding star in our home galaxy might be visible to Earth in the next 50 years, astronomers say in a new calculation of the odds of a nearby supernova.

This explosion would be too faint to prove a hazard to Earthlings, and in fact it may not even be visible with the naked eye in the starry sky. Its heat signature, however, would be seen in the right kind of camera as long as we could swing a telescope there fast enough.

“For [researchers], this study suggests that they have a solid chance of doing something that’s never been done before: detect a supernova fast enough to witness what happens at the very beginning of a star’s demise,” wrote Ohio State University in a press release about the research, which was led by university astronomer researcher Scott Adams.

Fishing Boats Meet the Milky Way on the Isle of Wight (south of England) on May 16, 2013. Credit and copyright: Chad Powell.

The challenge with observing a supernova in our own galaxy is the presence of cosmic dust that can sometimes obscure supernovae and other phenomena from our view. However, infrared light is not as badly affected by this and may be able to see something through the obscurity.

To jump on the supernova as it is happening, the scientists propose having a network in place to send out neutrino alerts when these particles, which would arrive at Earth first after an explosion, are detected on Earth. The key is to figure out the difference between neutrinos from space and neutrinos from other sources, such as nuclear reactors, the sun or even spurious glitches.

A University of Tokyo group led the building of a model of a new kind of neutrino detector, a model that is now operating underground in Japan. Called EGADS (Evaluating Gadolinium’s Action on Detector Systems), the water in the system would be “spiked” with a bit of gadolinium, which would reportedly assist with neutrino detections from outside of Earth.

The supernova that produced the Crab Nebula was detected by naked-eye observers around the world in 1054 A.D. This composite image uses data from NASA’s Great Observatories, Chandra, Hubble, and Spitzer, to show that a superdense neutron star is energizing the expanding Nebula by spewing out magnetic fields and a blizzard of extremely high-energy particles. The Chandra X-ray image is shown in light blue, the Hubble Space Telescope optical images are in green and dark blue, and the Spitzer Space Telescope’s infrared image is in red. The size of the X-ray image is smaller than the others because ultrahigh-energy X-ray emitting electrons radiate away their energy more quickly than the lower-energy electrons emitting optical and infrared light. The neutron star is the bright white dot in the center of the image. — The supernova that produced the Crab Nebula was detected by naked-eye observers around the world in 1054 A.D. This composite image uses data from NASA’s Great Observatories, Chandra, Hubble, and Spitzer, to show that a superdense neutron star is energizing the expanding Nebula by spewing out magnetic fields and a blizzard of extremely high-energy particles.

“When a neutrino from a Milky Way supernova enters the tank, it can collide with the water molecules and release energy, along with some neutrons,” Ohio State added. “Gadolinium has a great affinity for neutrons, and will absorb them and then re-emit energy of its own. The result would be one detection signal followed by another a tiny fraction of a second later—a “heartbeat” signal inside the tank for each detected neutrino.”

But what about a naked-eye supernova? The researchers say the probability of that is just 20% to 50% in the next century, with southern hemisphere residents having a better chance since more of the galaxy is visible there. The last instance of this happening, by the way, was in 1604.

The research paper is available now on prepublishing site Arxiv and will soon be published in the Astrophysical Journal.

Source: Ohio State University

Correction: This article has been changed to remove a reference to Ohio State University in the EGADS collaboration.

October 31, 2013December 23, 2015 by Nancy Atkinson

Halloween Astrophoto: The Witch Head Nebula

The Witch Head Nebula, taken on October 24, 2013. Credit and copyright: ftherrmann on Flickr.

Boo! Here’s a great shot of the Witch Head nebula, so named because it resembles the profile of a wicked witch. This nebula’s ‘official’ name is IC 2118, and it is just a cloud of interstellar gas and dust — nothing to be afraid of! The eerie shape is sculpted in part by radiation from the supergiant star Rigel, the brightest star of Orion. In fact, Rigel illuminates the nebula by reflecting off the dust grains, making it glow. Inside the nebula, young stars are being born. This image was taken by a former NASA scientist/engineer Fred Herrmann of the Owl Mountain Observatory near Huntsville, Alabama — ftherrmann2012 on Flickr. You can see an infrared image of this same nebula taken by the WISE spacecraft.

You can see more great images on Universe Today’s Flickr group page (click here to access, or see the new “Photos” tab at the top of our page) and feel free join the group and upload any astronomical images you have taken.

Happy Halloween from all of us here at Universe Today!

The Witch Head nebula is estimated to be hundreds of light-years away in the constellation of Orion. This image was taken by the WISE spacecraft. Credit: NASA.

October 31, 2013December 23, 2015 by Elizabeth Howell

SpaceX Signs Pact To Start Rocket Testing At NASA Stennis

The SpaceX Dragon capsule is snared by the International Space Station's Canadarm 2. Credit: NASA

SpaceX — the maker and operator of the Dragon spacecraft that runs periodic cargo flights to the International Space Station — has signed a contract to research, develop and test Raptor methane rocket engines at the NASA Stennis Space Center in southern Mississippi.

The California-based company plans to use the E-2 test stand at Stennis, which is able to support both vertical and horizontal rocket engine tests. (Here are some more technical details from NASA on its capabilities.)

“We have been talking with SpaceX for many years about working at Stennis Space Center, and I am pleased to officially welcome them to our Mississippi family. I hope this is just the beginning of their endeavors in our state,” stated U.S. Senator Thad Cochran (R-Miss) in response to the news. A press release from his office said the presence of the private space company would boost jobs in the region.

The E-2 test stand at NASA Stennis Space Center in southern Mississippi. The stand is used for vertical and horizontal rocket engine tests, among other things. Credit: NASA

There’s little information on SpaceX’s website about what the Raptor engine is or specific development plans, but Space News reports that it would be used for deep-space missions. SpaceX CEO Elon Musk has mentioned the engine previously when talking about Mars missions, according to multiple media reports.

“We are looking to test the whole engine at Stennis, but the first phase starts with the components,” SpaceX spokesperson Emily Shanklin said in the Space News report. “The E-2 stand at Stennis is big enough for components, but we would need a bigger stand for the whole Raptor.”

The two sides are reportedly hashing out a Space Act agreement to establish user fees and other parameters. Once that’s finished, the testing will begin, perhaps as early as next year. SpaceX currently does most of its rocket testing in Texas.

Other parties in the agreement — which was signed by Governor Phil Bryant — include the Mississippi Development Authority, the Harbor Commission and Hancock County Port.

October 31, 2013December 23, 2015 by Elizabeth Howell

Antarctic Sea Ice Takes Over More Of The Ocean Than Ever Before

Antarctica's sea ice on Sept. 22, 2013. Scientists say there was more ice on the ocean then than in any time in recorded satellite history. Data came from the Advanced Microwave Scanning Radiometer 2 (AMSR2) sensor on Japan’s Global Change Observation Mission 1st-Water (GCOM-W1) satellite. You can see the land in dark gray and ice shelves in light gray. The yellow line represents the average distribution of sea ice between 1981 and 2000. Credit: NASA/Jesse Allen, using data from the Advanced Microwave Scanning Radiometer 2 (AMSR2) sensor on the Global Change Observation Mission 1st-Water (GCOM-W1) satellite.

Antarctica’s sea ice is creeping further out in the ocean! New data from a Japanese satellite shows that sea ice surrounding the southern continent in late September reached out over 7.51 million square miles (19.47 million square kilometers).

The extent — a slight increase over 2012’s record of 7.50 million square miles (19.44 million square km) — is the largest recorded instance of Antarctica sea ice since satellite records began, NASA said. Data was recorded using the Advanced Microwave Scanning Radiometer 2 (AMSR2) sensor on the Global Change Observation Mission 1st-Water (GCOM-W1) satellite.

“While researchers continue to study the forces driving the growth in sea ice extent, it is well understood that multiple factors—including the geography of Antarctica, the region’s winds, as well as air and ocean temperatures—all affect the ice,” NASA stated.

Update — see below for a more detailed description of why this is an important clue that climate change IS happening.

“Geography and winds are thought to be especially important. Unlike the Arctic, where sea ice is confined in a basin, Antarctica is a continent surrounded by open ocean. Since its sea ice is unconfined, it is particularly sensitive to changes in the winds. As noted by the National Snow and Ice Data Center, some research has suggested that changes in Antarctic sea ice are caused in part by a strengthening of the westerly winds that flow unhindered in a circle above the Southern Ocean.”

For those thinking that increased sea ice means we can relax about climate change, this humorous video explains the difference between land ice (glaciers) and sea ice (which is generated from snow, rainfall and fresh water). It’s definitely worth four minutes of your time. The part about sea ice starts around 2:45.

UPDATE: Just to clarify:

Here’s what the graphic says: “The water around Antarctica is more fresh than it has been in previous years because of increased snow and rainfall as well as in increased contribution of fresh water from melting land ice. This fresh cold water is less dense than the warmer, saltier water below. Previously, that warm salty water would rise, melting the sea ice. But now, bcaus of the lighter fresh water on top, there is less mixing of the ocean’s layer and the surface stays cooler longer. “

And so, there is increased fresh water because of the melting land ice – due to climate change. There is a fundamental difference between sea ice and land ice. Antarctic land ice is the ice which has accumulated over thousands of years on the Antarctica landmass through snowfall. Antarctic sea ice is entirely different as it is ice which forms in salt water during the winter and almost entirely melts again in the summer.

Importantly, when land ice melts and flows into the oceans global sea levels rise on average; when sea ice melts sea levels do not change measurably but other parts of the climate system are affected, like increased absorption of solar energy by the darker oceans.

See this article on SkepticalScience for additional information.

Source: NASA Earth Observatory