Posted on by Fraser Cain

What Color is Neptune?

Neptune, captured by Voyager 2. Image credit: NASA

The color of Neptune is a bright azure blue. During its flyby in 1989, NASA’s Voyager 2 revealed the bright blue color, different from the pale blue color of Uranus. So why does Neptune have this color?

The answer to Neptune’s color comes from its cloud tops. The upper atmosphere of Neptune is made up of 80% hydrogen, 19% helium with a trace 1% amount of methane and other ices, like ammonia and water. Methane absorbs light at 600 nm, which is the red end of the spectrum of visible light.

Like all the planets in the Solar System, the light we see coming from Neptune is actually reflected light from the Sun. These methane clouds absorb the red end of the spectrum, and allow the blue end of the spectrum to bounce back out. So when you see the color of Neptune, you’re seeing reflected sunlight with the red light stripped out.

From a distance, Neptune looks just like a blue ball, but as you get closer you can see variations in its clouds. Lighter clouds of methane hang above the lower cloud deck. Powerful storms whip across the surface of Neptune; the fastest storms in the Solar System are on Neptune, with winds exceeding 2,400 km/hour. Neptune has a large dark storm, similar to the Great Red Spot on Jupiter.

We have written many articles about Neptune on Universe Today. Here’s an article about “movies” of Neptune captured by Hubble. And some additional images captured by Hubble that really show the color of Neptune.

If you’d like more information on Neptune, take a look at Hubblesite’s News Releases about Neptune, and here’s a link to NASA’s Solar System Exploration Guide to Neptune.

We have recorded an entire episode of Astronomy Cast just about Neptune. You can listen to it here, Episode 63: Neptune.

Posted on by Fraser Cain

What is the Atmosphere of Neptune Like?

Neptune, captured by Voyager. Image credit: NASA/JPL

The atmosphere of Neptune is similar to all the large planets in the Solar System; it mostly consists of hydrogen and helium, with trace amounts of methane, water, ammonia and other ices. But unlike the other gas planets in the Solar System, Neptune’s atmosphere has a larger proportion of the ices. It’s the methane in the planet’s upper atmosphere that give it its bright blue color.

At the highest altitudes, where the Neptune’s atmosphere touches space, it consists of about 80% hydrogen and 19% helium. There’s also a trace amount of methane. The light we see from Neptune is actually the reflected light from the Sun. Although the entire spectrum of light hits Neptune. This trace amount of methane absorbs light from the red end of the spectrum, while allowing the blue light to bounce back out. The color of Neptune’s atmosphere is brighter than Uranus, which has a similar atmosphere; astronomers aren’t sure why there’s such a dramatic color difference.

The upper level clouds on Neptune occur at the point where pressures are low enough for methane to condense. Astronomers have photographed these high altitude clouds forming shadows onto the lower cloud deck below. Deeper down inside Neptune, temperatures should get up to 0 C, where clouds of water might form.

As with the other planets, the atmosphere of Neptune is broken up into distinct bands of storms. In fact, the fastest moving winds in the Solar System occur at Neptune – winds have been clocked at 2,400 km/h (1,500 miles per hour). Some storms can grow large and remain for long periods of time. Neptune has its own Great Dark Spot, similar to the Great Red Spot on Jupiter.

We have written many articles on Universe Today about the atmosphere of Neptune and its storms. Here’s an article about the weather in springtime on Neptune, and how Neptune’s south pole might be the warmest place on the planet.

If you’d like more information on Neptune, take a look at Hubblesite’s News Releases about Neptune, and here’s a link to NASA’s Solar System Exploration Guide to Neptune.

We have recorded an entire episode of Astronomy Cast just about Neptune. You can listen to it here, Episode 63: Neptune.

Posted on by Fraser Cain

Volcanoes on the Moon

Basalt deposits on the Moon. Image credit: NASA

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When we look at the Moon, we see a landscape shaped by impact craters. But scientists only discovered the true cause of crater in the last hundred years. Before that, they believed that there were many volcanoes on the Moon, and this is what caused the craters we see today.

Now we know that craters come from meteorite impacts, that still doesn’t answer the question: are there volcanoes on the Moon?

There used to be volcanoes on the Moon. The Moon is much smaller than the Earth. Although it was molten after its formation, it cooled down relatively rapidly. Scientists think that the Moon’s interior remained hot enough to produce magma for about a billion years after the Moon formed. The lava that came out of the Moon cooled quickly, and formed fine-grain, dark rocks called basalt. The Apollo astronauts sampled this material when they landed on the Moon.

When you look at the Moon, you see lighter and darker regions. The lighter regions are the mountainous highlands. The darker regions are vast “seas” of basalt lava that erupted out of the Moon billions of years ago.

Are there volcanoes on the Moon today?

There is recent evidence that there were volcanoes on the far side of the Moon much longer than on the near side. While the near side of the Moon shut down more than 3 billion years ago, there seems to be evidence that there were volcanoes on the surface of the Moon as recent as about a billion years ago.

Some researchers believe there are still vents that blast out volcanic gasses, but there are no longer active volcanoes on the Moon.

Want more information about the Moon? Here’s NASA’s Lunar and Planetary Science page. And here’s NASA’s Solar System Exploration Guide.

You can listen to a very interesting podcast about the formation of the Moon from Astronomy Cast, Episode 17: Where Did the Moon Come From?

Posted on by Nancy Atkinson

Hanny’s Voorwerp Revealed?

Hanny's Voorwerp. Credit: ASTRON

Ever since Hanny Van Arkel found an unusual object while scanning through images as an enthusiastic Galaxy Zoo volunteer, astronomers and astronomy enthusiasts have wondered what the bizarre object, known as “Hanny’s Voorwerp” actually is. Now, new observations made by radio telescopes may have finally revealed the nature of the Voorwerp (Dutch for “object.”) It appears as though a jet of highly energetic particles is being generated by a massive black hole at the center of IC2497, creating an ionized gas cloud.

While surfing through hundred’s of images over a year ago, Hanny, a Dutch school teacher noticed a huge green irregular cloud of gas of galactic scale, located about 60,000 light years from a nearby galaxy, IC2497. The cloud is enormous and the gas is extremely hot (> 15,000 Celsius) but paradoxically it is devoid of stars.

An international team of astronomers, led by Prof. Mike Garrett, and also Hanny van Arkel herself, have observed IC2497 and the Voorwerp with the Westerbork Synthesis Radio Telescope (WSRT) and an e-VLBI array in which the WSRT also participated.

“It looks as though the jet emanating from the black hole clears a path through the dense interstellar medium of IC 2497 towards Hanny’s Voorwerp”, says Garrett. “This cleared channel permits the beam of intense optical and ultraviolet emission associated with the black hole, to illuminate a small part of a large gas cloud that partially surrounds the galaxy. The optical and ultraviolet emission heats and ionizes the gas cloud, thus creating the phenomena known as Hanny’s Voorwerp.”

One remaining question is where does all the hydrogen gas come from? “There is a lot of gas out there – the WSRT observations detect a huge stream of gas that is extended across hundreds of thousands of light years”, says Dr. Gyula Józsa, another member of the team. According to Józsa the total mass of gas is about 5000 million times the mass of the sun. It’s something Dr. Tom Oosterloo thinks he has seen before: “It has all the hallmarks of an interacting system – the gas probably arises from a tidal interaction between IC 2497 and another galaxy, several hundred million years ago.”
WRST. Credit: ASTRON
Oosterloo also thinks he can identify the culprits, “the stream of gas ends three hundred thousand light years westwards of IC2497 – all the evidence points towards a group of galaxies at the tip of the stream being responsible for this freak cosmic accident”.

Hanny van Arkel, who is visiting the team at ASTRON this week is impressed. “I’m happy we are making progress. Apparently the more we learn about the Voorwerp, the more intriguing it becomes”. Garrett and his team agree – “We think the Voorwerp has a few more secrets to reveal”. The team plan much deeper observations with the WSRT and with other telescopes soon.

Source: ASTRON

Posted on by Nancy Atkinson

Unusual Red Spiral Galaxies “Strangled”

Images of three galaxies from the Galaxy Zoo (top) and STAGES surveys (bottom) show examples of how the newly discovered population of red spiral galaxies on the outskirts of crowded regions in the Universe may be a missing link in our understanding of galaxy evolution.

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Usually a galaxy’s shape corresponds with its color as well as its age. Spiral galaxies appear blue because they are still dynamically forming hot young stars. Elliptical galaxies, on the other hand, are mostly old, dead, and red. But surprisingly, two international collaborations have both separately identified a population of unusual red spiral galaxies. Galaxy Zoo, which uses volunteers from the general public to classify galaxies and the Space Telescope Galaxy Evolution Survey (STAGES) project have found that many of the red galaxies in crowded regions of galaxy clusters are actually spiral galaxies, bucking the trend for red galaxies to be elliptical in shape. However, these galaxies might be in transition, going from young to old, slowly having the life ‘choked’ out of them. “We think what we’re seeing is galaxies that have been gently strangled, so to speak,” said Chris Lintott, Galaxy Zoo team leader from University of Oxford, “where somehow the gas supply for star formation has been cut off, but that they’ve been strangled so gently that the arms are still there.” Sounds like a CSI murder mystery, but in this case astronomers are studying the scene of the crime.

The STAGES team used the Hubble Space Telescope to look in detail at one particular very large cluster of galaxies, known as the A901/902 and found a surprisingly large number of red spiral galaxies. But they didn’t know if what they were seeing was unusual to only that cluster or even that particular region of space. However the Galaxy Zoo team had found red spirals all across the universe. “STAGES had more detailed observations,” said Linott, “but we showed this is something that happens across the population of galaxies. So it’s nice when you can attack it from both ends at once.”

The two teams have concluded that both the mass of a galaxy as well as its local environment are important in determining when and how quickly its star formation is shut down. The red spirals are found on the outskirts of clusters in crowded regions of space where galaxies cluster together. As a blue galaxy is drawn in by gravity from the rural regions to the suburbs, some sort of an interaction with its environment causes a slow-down in star formation. The closer in a galaxy is, the more it is affected.

Also, the red spirals were also the more massive galaxies, presumably because the smaller ones are transformed more quickly.

So what causes the transformation? The two teams don’t think it was any type of violent interaction.

“Usually, anything disruptive enough to get rid of the gas that fuels the star formation would have disrupted the spiral arms,” said Lintott. “But not so, at least particularly on the outskirts of clusters.” said Lintott.

The cause might be just the galaxy’s gentle interaction with the cluster. “The kind of thing we’re imagining,” explained Lintott, “as the galaxy moves into a denser environment, there’s lot of gas in clusters as well as galaxies, and it’s possible the gas from the galaxy just gets stripped off by the denser medium it’s plowing into.”

The teams have ruled out that a huge quantity of dust in these galaxies is masking a large amount of blue star formation. “Whenever you show a red object to an astronomer they immediately blame dust,” said Lintott, “because dust can absorb light and re-scatter it at a longer wavelength. So the temptation is to say they are just normal galaxies with just lots of dust. But there’s something else going on here, because then you’d expect the effect to be stronger if the spiral was face-on rather than edge- on because you’re looking at more of the galaxy. But we see the red spirals even in galaxies that are face-on. So we know it’s not just the effect of dust and inclination. So the obvious explanation is gone.”

Galaxy Zoo’s armchair astronomers’ biggest contribution wasn’t just the amount of galaxies they could look at (although the 100,000 plus they classified from the Sloan Digital Sky Survey was key) but more importantly, they are classifying galaxies purely by shape. “Since most elliptical galaxies are red and most spirals are blue,” said Lintott, ” if you’re sorting galaxies in an automated way, it’s very tempting to use color to sort them. But because we have people doing this we could separate the two out. So first we found all the spirals, and then we looked at their colors.”

This work is just the beginning of more investigations into these unusual red spiral galaxies. “This paper is our first look at all of this,” Lintott said. “One thing we’re particularly excited about that we’re working on now is looking to see what the black holes in these galaxies are doing. Whenever you see star formation being turned off, we like to blame the black hole. So it will be interesting to see what’s going on there.”

For more information:
Galaxy Zoo
STAGES

Galaxy Zoo’s paper
STAGES paper

Sources: RAS, interview with Chris Lintott

Posted on by Nicholos Wethington

Supersonic Bubbles Blown By Black Holes Regulate Size

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Apparently, black holes can walk and chew gum at the same time. Or at least they can chew up gas and dust and blow supersonic bubbles with it at the same time. Analysis into the formation of large bubbles of plasma formed by supermassive black holes reveals that creating the bubbles may stunt the growth of the black hole, as well as curb star formation in elliptical galaxies.

Many galaxies (including our own Milky Way) contain a black hole at the center, which constantly sucks in material from the surrounding regions. As the material gets close to the black hole, it bunches up, jostling with other material being sucked into the black hole and giving off energy. This process powers quasars – jets of radio and light emissions beamed into space.

A team of international astronomers imaged the elliptical galaxy M84 using the Chandra X-ray observatory. M84 has just such a black hole, and at the ends of each of its jets large cavities of ionized gas (plasma) form. The bubbles measure 13,000 light years across, and are formed about every 10 million years.

The constant cycle of bubbles being blown inside of each other, then “popping” and releasing their energy to the may slow the stream of matter that flows into the black hole.

As the outer bubble leaks its energy into the surrounding interstellar medium and disperses, the next bubble expands to take its place. Colder matter surrounding a black hole (outside the event horizon) is absorbed more readily than warmer matter. In the same way that heat rises in your house, hot gas surrounding the black hole is harder for it to capture, so the bubbles slow the growth of the black hole by siphoning off the matter and energy it could potentially feed on.

Four bubbles surrounding the M84 galaxy's black hole. The top bubble is bursting and spilling its energy away from the black hole Image Credit: A.Finoguenov et al.

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And as if bubbles of plasma 13,000 light years across surrounding a black hole weren’t impressive enough, the transfer of thermal energy into mechanical energy creates shock waves traveling at hypersonic speeds that expand the bubbles. Try getting your standard bubble blowing apparatus to do that!

The transfer of energy into the gas contained in an elliptical galaxy could potentially limit the amount of star formation there, in addition to stunting the growth of the supermassive black hole. Stars form out of the dust and gas in the interstellar medium, and the hotter the gas and dust is, the less likely it is to clump up due to gravitational interaction with surrounding material and snowball enough to create a star.

The results are be published in the Oct. 20th issue of the Astrophysical Journal, and the pre-print article can be found on Arxiv.

Source: Space.com

Posted on by Nancy Atkinson

Sources of Earth-Bombarding Cosmic Rays May Have Been Located

The cosmic ray hot spots were identified in the two red-colored regions near the constellation Orion. Courtesy John Pretz, LANL

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Last week’s announcement of a puzzling and unknown source of high energy cosmic rays bombarding the Earth is now joined by another discovery of two sources of unexpected cosmic rays from nearby regions of space. A Los Alamos National Laboratory cosmic-ray observatory has seen for the first time two distinct hot spots that appear to be bombarding Earth with an excess of cosmic rays. “These two results may be due to the same, or different, astrophysical phenomenon, said Jordan Goodman, principal investigator for the Milagro observatory, commenting on last week’s announcement by the ATIC experiment and the new discovery by his team. “However, they both suggest the presence of high-energy particle acceleration in the vicinity of the earth. Our new findings point to general locations for the localized excesses of cosmic-ray protons.” The cosmic rays appear to originate from an area in the sky near the constellation Orion.

Researchers used Los Alamos’ Milagro cosmic-ray observatory to peer into the sky above the northern hemisphere for nearly seven years starting in July 2000. The observatory is unique in that it monitors the entire sky above the northern hemisphere. Because of its design and field of view, Milagro was able to record over 200 billion cosmic-ray collisions with the Earth’s atmosphere.

Cosmic rays are high-energy particles that move through our Galaxy from sources far away. No one knows exactly where cosmic rays come from, but scientists theorize they might originate from supernovae—massive stars that explode— from quasars or perhaps from other exotic, less-understood or yet-to-be-discovered sources within the universe.

“Our observatory is unique in that we can detect events of low enough energies that we were able to record enough cosmic-ray encounters to see a statistically significant fractional excess coming from two distinct regions of the sky,” said collaborator Brenda Dingus.

Because Milagro was able to record so many cosmic-ray events, researchers for the first time were able to see statistical peaks in the number of cosmic-ray events originating from specific regions of the sky near the constellation Orion. The region with the highest hot spot of cosmic rays is a concentrated bulls eye above and to the right visually of Orion, near the constellation Taurus. The other hot spot is a comma-shaped region visually occurring near the constellation Gemini.

But the researchers cannot be sure they have precisely located the sources of the cosmic rays. “Whatever the source of the protons we observed with Milagro, their path to Earth is deflected by the magnetic field of the Milky Way so that we cannot directly tell exactly where they originate,” said Goodman. “And whether the regions of excess seen by Milagro actually point to a source of cosmic rays, or are the result of some other unknown nearby effect is an important question raised by our observations.”

A new, second-generation cosmic ray observatory has been proposed, which may be able to solve the mystery of the origin of cosmic rays. The experiment, named the High Altitude Water Cherenkov experiment (HAWC), would be built at a high-altitude site in Mexico.

Sources: UMD, Science Daily

Posted on by Nancy Atkinson

Mr. Fixit In Space Invents Zero-G Coffee Cup

Pettit and the Zero G Coffee Cup. Credit: NASA TV

I have no doubt that the astronauts on board the International Space Station and shuttle Endeavour will be able to fix the balky urine recycling water system. Why? Mr. Fixit is part of the crew.

During his stay on the ISS in 2002/2003 as part of Expedition 6, astronaut Don Pettit became well known for his Saturday Morning Science and tinkering with broken hardware. He’s also renowned among astronauts for building or fixing things with paper clips. But now as part of the STS-126 shuttle crew, he has invented something close to his heart: a zero-g coffee cup.

Like many Americans, Pettit loves his coffee. But drinking coffee from a bag just isn’t the same as sipping and savoring your morning brew. Until now, all liquids have been sipped from a bag in space because of how liquids operate in a zero gravity environment. But during his off-time on Sunday, Pettit used a piece of plastic ripped from his Flight Data File mission book and folded it into a airplane-wing shaped cup.

How does it work?

Surface tension inside the cup keeps the coffee from getting out and floating around the ISS and possibly causing problems.

“We’re no longer sipping from a bag, we can drink from a cup,” said Pettit. “With the special shape of this cup, the surface tension forces will wick the coffee up along the edge.”

The cross section of the cup looks like an airplane wing, and the narrow angle will ‘wick’ the liquid up. “This is what we use when we design fuel tanks for rockets to reignite in weightless environment,” said Pettit. “The veins in the tank will wick the fluids into the suction port. Knowing this for a fuel tank, you can make a cup, and you can enjoy sipping a cup of coffee instead of drinking from a bag.”

See a video here from on collectSPACE.

But Pettit was also busy yesterday using his tinkering skills to fix the water recycling system which will allow astronauts to convert urine, sweat and other used water into potable water. The problem with the system appears to be too much vibration from a centrifuge motor, and on Sunday Pettit removed some rubber dampers from a distillation assembly in hopes of fixing the problem. While the system ran longer than it has previously, it ultimately shut down once again.

The water recycling system is crucial for NASA’s plans to increase the station’s crew size from three to six in May 2009. NASA managers had hoped to collect test water from the urine recycling system and send samples home with the shuttle crew for testing to make sure the water is safe for drinking and cooking.. and making coffee. So, with Pettit aboard, I’m thinking the water recycling system is in good hands, and fixing it is probably a priority for him.

“I like to call it the coffee machine,” said Pettit in an interview before launch about the urine to water system. “It will take yesterday’s coffee and turn it into today’s coffee.”

Sources: collectSPACE, Space.com

Posted on by Nancy Atkinson

Satellite Tracker Captures Lost Toolbag on Video

j Toolbag just out of the reach of Heide Stefanyshn-Piper. Credit: AP/NASA TV

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The toolbag lost by spacewalkers this past week is being tracked by satellite observers and one veteran observer actually captured the toolbag whizzing by on video! Kevin Fetter from Brockville, Ontario video-recorded the backpack-sized toolbag last night, Nov. 22 from his backyard. “It was easily 8th magnitude or brighter as it passed by the 4th magnitude star eta Pisces,” Fetter said. Check out the video here. What these “amateurs” can’t do these days! If you’d like to try to see the toolbag yourself, here’s the link to Space Weather’s Satellite Tracker, so you can find out when it will be traveling over your backyard. This site provides satellite observations times for residents of the US and Canada. The expensive toolbag floated away from Endeavour astronaut Heidemarie Stefanyshyn-Piper during the STS-126 mission’s first spacewalk on Nov. 18th. Whoever said the toolbag was lost never to be seen again!

And just why does that toolbag cost $100,000?

Lost tool bag floats away from the ISS. Credit: NASA
Lost tool bag floats away from the ISS. Credit: NASA

“The cost included the EVA crew lock bag itself, four retractable tethers, two adjustable equipment tethers, a grease gun with a straight nozzle, two wire ties, a grease gun with a J-hook nozzle, an EVA wipe caddy, six EVA wipes (two wet, four dry), a scraper debris container, a SARJ scraper and a large trash bag,” NASA spokesman Mike Curie.

Most of that equipment and the bag are not just something you can pick up at your local hardware store. They are specialized hardware that had to be specifically created and certified for the harsh environment of space, able to work properly in a vacuum and withstand temperature swings from plus 200 degrees F (93 C) and minus 200 degrees F (-128 C).

And if you want to complain about astronauts losing things in space, then you go put on a pair of bulky, stiff gloves and a spacesuit (and a diaper) and try to do some very intricate, demanding work in zero gravity for about seven hours!

sources: SpaceWeather.com, Orlando Sentinel

Posted on by Nancy Atkinson

Bright Meteor Seen Over Western Canada

Images of the meteor. Credit: SpaceWeather.com

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A bright fireball lit up the sky over parts of Canada and was probably a meteor which may have hit the ground in central Alberta. Reports from all over western Canada said the bright flashes occurred at 5:30 pm MST on Nov. 20. The bolide split the evening sky and fragmented during a series of booming explosions. The image above is from a video taken by Andy Bartlett, who recorded the event from a 10th-floor apartment in Edmonton, Alberta with his Canon A510. Watch the movie here. “The brilliant fireball appeared to be closer than the airplane in the upper right corner of this video,” said Bartlett. Another video was taken by a serendipitously placed surveillance camera. See a news report from a Canadian television station here.

So what was this object?

The possibility of the object being part of a Russian rocket has been ruled out, but astronomers say it will take time for experts to work through videos and photos to find out what exactly occurred. Astronomers need views of the event from at least two sites to triangulate where a meteorite might have hit and where any small pieces could possibly be found. However, it may have burned up completely in the atmosphere. One educator said the object was probably no bigger than the size of a grapefruit as it entered Earth’s atmosphere, probably traveling about 60 km per second.

Sources: Space Weather
, MSN news