Posted on by Fraser Cain

Pluto Atmosphere

Artist's impression of a comet's surface. Image credit: NASA/JPL

Yes, that’s right, Pluto does have an atmosphere. Well, the Pluto atmosphere is not the ocean of air we have here on Earth, but Pluto’s thin envelope of gases do surround the dwarf planet for part of its orbit around the Sun.

You can also look through these books from Amazon.com if you want more information about Pluto.

It’s important to understand that the orbit of Pluto is very elliptical, bringing it closer and then more distant at various points of its orbit. At the closest point, the surface of solid nitrogen heats up enough that it sublimates – changes directly from a solid to a gas.

These clouds of nitrogen surround Pluto, but it doesn’t have enough gravity to keep them together, so they can escape out into space.

And then, as Pluto gets further from the Sun again, it cools down, and the atmosphere freezes and solidifies back down on the surface of Pluto.

In 1988, astronomers discovered that Pluto has an atmosphere by watching how it passed in front of a more distant star – called a planetary transit. Instead of dimming the moment it went behind Pluto, the star was first obscured by the atmosphere, so that astronomers could measure its thickness and composition.

It currently has 3μbar on the surface and its height extends 60 km above the surface.

More precise observations were done in 2002, when astronomers were surprised to find that Pluto’s atmosphere had actually thickened since it had first been discovered. Astronomers think this is a seasonal phenomenon. The nitrogen on Pluto’s surface was exposed to sunlight following a 120-year winter. The nitrogen became a gas, but it took time to get going as an atmosphere.

As Pluto is now traveling away from the Sun, the Pluto atmosphere won’t last long. Astronomers think it will begin to disappear by 2015. This is one of the big reasons NASA sent its New Horizons spacecraft – to study Pluto’s atmosphere before it’s gone for good.

Posted on by Fraser Cain

Moons of Pluto

When Pluto was first discovered back in 1930, astronomers thought it was just a single, solitary planet orbiting the Sun. Almost 50 years later, astronomers discovered that it actually had a very large moon. And then in 2005, astronomers working with the Hubble Space Telescope announced that they had found two more moons of Pluto, officially named Nix and Hydra. Are there more, waiting to be found? How many moons does Pluto have?

Astronomers now know that Pluto has three natural satellites. The first and largest of the Pluto moons is Charon, first identified back in 1978 by astronomer James Christy. He made the discovery while examining a photograph of Pluto and noticed that it had a bulge on one side. Christy and his colleagues thought this bulge came from a defect in the alignment of the telescope, but then they noticed that only Pluto was elongated, and not the background stars. They realized they were looking at a moon for Pluto.

Pluto’s moon Charon is named after the boatman in Greek mythology who guides the dead across the River Styx. This works well, considering Pluto is the roman god of the underworld (no, not the Disney Dog).

Charon is large and massive, compared to its parent dwarf planet Pluto. While Pluto measures 2,306 km across, Charon is 1,205 km.across.

One of the remarkable things about Pluto and Charon is that they’re actually a binary system. The two objects orbit a common center of gravity which is outside Pluto itself. For comparison, the Earth and Moon’s center of gravity is inside the Earth.

Back in 2005, astronomers working with the Hubble Space Telescope discovered two additional Pluto moons; they named them Nix and Hydra (originally S/2005 P1 and S/2005 P2). Nix measures 46 km across, and Hydra is 61 km. The Hubble research suggested a n upper limit for moon sizes orbiting Pluto. It appears that Pluto has already reached this limit with Nix and Hydra, and anything larger would be clearly visible.

The discovery of these moons has given hope to the theory that Pluto has a ring system, created with micrometeorites impact with the surface of the dwarf planet. Another possibility is that Charon produces ice geysers, similar to Saturn’s moon Enceladus.

More on this will be discovered when NASA’s New Horizons spacecraft finally arrives at Pluto in 2015. At its closest point, New Horizons will get within 10,000 km of the dwarf planet’s surface, and capture images at an unprecedented level of quality.

We’ll finally know what Pluto really looks like. And we’ll get a chance to see Pluto’s other moons at the same time.

Go here if you’d like a picture of Pluto.

Source: NASA

Posted on by Fraser Cain

Pictures of Pluto

Pluto is so small and distant that we just don’t have any good pictures of it… yet. We get so many people asking that I’ve compiled together a gallery of the best pictures of Pluto. Some of these are actual Pluto pictures, captured by telescopes, while others are pics of Pluto done by an artist. Once NASA’s New Horizons spacecraft finally arrives in 2015, we’ll get some actual, close up images of Pluto and its moon Charon.

Even though Pluto’s not a planet any more, we can’t wait to see what it’s going to look like.

Each image links to a version you can use as your desktop background. To do this, click on an image to see the larger version, and then right-click and choose “Set as desktop”. Now you’ll have the picture as your background.

You can also look through these books from Amazon.com if you want more information about Pluto.

This is one of the best hubble pics of Pluto ever taken. It was photographed by the Hubble Space Telescope in 1994. The image clearly shows both Pluto and Charon as separate disks with surface features.

This is a picture of Pluto, captured by the Hubble Space Telescope. The photograph of Pluto was taken when the dwarf planet was 4.8 billion km (3 billion miles) from Earth. Hubble was able to see lighter and darker patches across the surface of Pluto. What’s happening here? We’ll have to wait for New Horizons to know better.

This is an artist’s illustration picture of Pluto and Charon seen from one of its smaller moons. Pluto is the large disk right in the middle of the photograph, and Charon is the smaller one over to the right. Pluto’s other tiny moon is the bright object to the left, just above the horizon. (Image credit: NASA).

Here’s a new portrait of the Solar System, with tiny Pluto and the other dwarf planets. You can see how they compare in size to the rest of the planets.

This is a picture of Pluto being visited by NASA’s New Horizons spacecraft. The actual encounter is going to happen in 2015, when the first close-up images of the surface of Pluto will be sent back to Earth.

I hope you enjoyed these Pluto pics.

Posted on by Fraser Cain

Pluto

Take a look at the Solar System from above, and you can see that the planets make nice circular orbits around the Sun. But dwarf planet’s Pluto’s orbit is very different. It’s highly elliptical, traveling around the Sun in a squashed circle. And Pluto’s orbit is highly inclined, traveling at an angle of 17-degrees. This strange orbit gives Pluto some unusual characteristics, sometimes bringing it within the orbit of Neptune. Credit: NASA

Take a look at the Solar System from above, and you can see that the planets make nice circular orbits around the Sun. But dwarf planet’s Pluto’s orbit is very different. It’s highly elliptical, traveling around the Sun in a squashed circle. And Pluto’s orbit is highly inclined, traveling at an angle of 17-degrees. This strange orbit gives Pluto some unusual characteristics, sometimes bringing it within the orbit of Neptune.

Pluto takes 248 years to complete one full orbit around the Sun. During this journey, the orbit of Pluto ranges in distance from the Sun following an elliptical orbit. At its closest point, it can be 30 astronomical units from the Sun (1 AU is the distance from the Earth to the Sun). At its furthest point, Pluto is 39 AU from the Sun.

Astronomers call this orbit eccentric because Pluto follows an orbit that traces out an elongated ellipse around the Sun.

Pluto’s orbit is also highly inclined. This means that it doesn’t orbit within the same plane as the rest of the Solar System. Instead, Pluto orbits at an angle of 17-degrees. For part of its orbit, Pluto is above the plane of the ecliptic (where the other planets orbit) and other times it’s below that plane.

Because the orbit of Pluto varies so widely, it can switch places with Neptune, orbiting closer to the Sun. The last time this happened was on February 7, 1979. Pluto remained closer to the Sun than Neptune until February 11, 1999. And the previous time it happened was back in the 1700s.

With its low mass, Pluto’s orbit is actually quite chaotic through its interactions with Neptune. Although astronomers can predict its position forward and backwards in time for a few million years, the uncertainties mount up, and it’s impossible to know where it’ll be in the far future.

As you probably know, Pluto is no longer a planet. This was a decision handed down in the 2006 meeting of the International Astronomical Union. Although Pluto orbits the Sun and has enough mass to pull itself into a sphere, it hasn’t cleared out its orbit.

They’ll never collide, though. Pluto is in a 3:2 resonance with Neptune. This means that for every three orbits Neptune makes going around the Sun, Pluto makes two. They always end up in the same positions. This whole process takes about 500 years to complete.

Just to give you an example, Pluto’s mass is only 0,07 times the mass of all the other material in its orbit. Earth, in comparison, has 1.5 million times the mass of everything else in its orbit.

Because it hasn’t cleared out this material, Pluto was designated as a dwarf planet, along with asteroid Ceres and the newly discovered Eris, which is actually larger than Pluto.

We have written many interesting articles about Pluto here at Universe Today. Here’s facts on Pluto.

Source:

Posted on by Fraser Cain

Carnival of Space #51

Again we move to a new home with the Carnival of Space. This week we’re at the home of Dr. Ian O’Neill and his blog Astroengine. This is the largest carnival ever, with a week’s worth of writing that will take you a week to read.

Click here to read the Carnival of Space #51

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, let me know if you can be a host, and I’ll schedule you into the calendar.

Finally, if you run a space-related blog, please post a link to the Carnival of Space. Help us get the word out.

Posted on by Fraser Cain

Mars Was Recently Blanketed By Glaciers

Mars is a dead world, unchanging for billions of years. Right? Maybe not. Researchers from Brown University have found evidence for thick, recurring glaciers on the surface of Mars. This means that the climate on Mars might be much more dynamic than previously believed. Perhaps the climate could change again. And liquid water underneath these glaciers might have given life a refuge over the eons.

Around 3.5 billion years ago, Mars was a completely different world, with liquid water right there on its surface. And then something happened that made it cold, dry, and quiet – too quiet. Apart from the occasional meteorite impact, planetary geologists thought that very little has happened on Mars since then.

In an article published in the journal Geology, scientists from Brown University released images showing how dynamic Mars might be. They found evidence that thick ice packs, at least 1 km (0.6 miles) thick and maybe 2.5 km (1.6 miles) thick coated Mars’ mid-latitude regions.

These ice sheets weren’t there last year, but they were there 100 million years ago, and maybe localized glaciers were flowing as recently as 10 million years ago. That’s yesterday, geologically speaking.

With activity this recent on Mars, that could mean that its climate might change often, and it could happen again. Maybe Mars wasn’t so dead for the last 3.5 billion years.

The images captured by NASA’s Mars Reconnaissance Orbiter showed a box canyon in a low-lying plain. The canyon clearly has moraines – deposits of rock that mark the end of the glacier, or the path of its retreat.

This discovery increases the possibility of life on the surface of Mars. At the bottom of the glaciers, crushed under kilometres of ice, liquid water would have formed into vast reservoirs. These could have served as sanctuaries for life.

Original Source: Brown University News Release

Posted on by Fraser Cain

Magnetic Fields Shape the Jets Pouring Out of Supermassive Black Holes (with video)

Artist's impression of a supermassive black hole. Credit: NRAO

The cores of galaxies contain supermassive black holes, containing hundreds of millions of times the mass of Sun. As matter falls in, it chokes up, forming a super hot accretion disk around the black hole. From this extreme environment, the black hole-powered region spews out powerful jets of particles moving at the speed of light. Astronomers have recently gotten one of the best views at the innermost portion of the jet.

A team of astronomers led by Alan Marscher, of Boston University, used the National Radio Astronomy Observatory’s Very Long Baseline Array (VLBA) to peer at the central region of a galaxy called BL Lacertae.

“We have gotten the clearest look yet at the innermost portion of the jet, where the particles actually are accelerated, and everything we see supports the idea that twisted, coiled magnetic fields are propelling the material outward,” said Alan Marscher, of Boston University, leader of an international research team. “This is a major advance in our understanding of a remarkable process that occurs throughout the Universe,” he added.

Here’s how the theory goes. As material falls into the supermassive black hole faster than it can consume it, an accretion disk forms. This is a flattened, rotating disk that circles the black hole. The spinning interaction with the black hole creates powerful magnetic fields that twist and form into a tightly-coiled bundle. It’s these magnetic fields that blast out particles into focused beams.

The theorists expected that the region inside the acceleration region would follow a corkscrew-shaped path inside the twisting magnetic fields. Furthermore, researchers expected that light and material would brighten when it was pointed directly towards Earth. And finally, the astronomers expected that there should be a flare when material hits a stationary shock wave called the “core” after it comes out of the acceleration region.

And that’s just what the observations show. The VLBA was used to study how a knot of material was ejected out of the black hole’s environment. As the knot moved through the stationary shock wave, it flared just as the theorists had predicted.

Original Source: NRAO News Release

Posted on by Fraser Cain

Podcast: Detectors

Our senses can only detect a fraction of the phenomena happening in the Universe. That’s why scientists and engineers develop detectors, to let us see radiation and particles that we could never detect with our eyes and ears. This week we’ll go through them all, so you can understand how we see what we can’t see.

Click here to download the episode

Detectors – Show notes and transcript

Or subscribe to: astronomycast.com/podcast.xml with your podcatching software.

Posted on by Fraser Cain

Will the Large Hadron Collider Destroy the Earth?

Large Hadron Collider
Large Hadron Collider

Question: Will the Large Hadron Collider Destroy the Earth?

Answer: No.

As you might have heard in the news recently, several people are suing to try and get the Large Hadron Collider project canceled. When it finally comes online, the LHC will be the largest, most powerful particle accelerator ever constructed.

If there’s something wrong with it, the LHC might have the power to damage itself, but it can’t do anything to the Earth, or the Universe in general.

There are two worries that people have: black holes and strange matter.

One of the goals of the Large Hadron Collider is to simulate microscopic black holes that might have been generated in the first few moments of the Big Bang. Some people are worried that these artificial black holes might get loose, and then consume the Earth from within, eventually moving on to destroy the Solar System.

The physicists are confident that any black holes they create will evaporate almost instantaneously into a shower of particles. In fact, the theories that predict that black holes can be created also predicts that black holes will evaporate. The two concepts go hand in hand.

The other worry is that the Large Hadron Collider will create a theorized material called strangelets. This “strange matter” would then be able to infect other matter, turning the entire planet into a blog of strange matter.

This strange matter is completely theoretical, and once again, the same theories that say it might be produced in the Large Hadron Collider also rule out any risks from it.

One of the most important considerations is the fact that the Moon is struck by high energy cosmic rays that dwarf the power of the Large Hadron Collider. They were likely blasted out of the environment around a supermassive black hole.

These have been raining down on the Moon for billions of years, and so far, it hasn’t turned into a black hole or strange matter.

You can read more about the Large Hadron Collider lawsuit here. Or how it might create wormholes, a view into other dimensions, or unparticles.