Posted on by Fraser Cain

Trailer for the International Year of Astronomy 2009

Okay, now I’m getting excited. As I’ve mentioned in the past, and will bring up again and again, the UN has designated 2009 as the International Year of Astronomy. There are some really great projects planned that will try to get as many people as possible interested in astronomy. The IYA has released a cool trailer to get us all inspired. It’s working for me.

Posted on by Fraser Cain

What is Pluto Made Up Of

No longer a planet, Pluto is just a member of the Kuiper Belt; a collection of icy objects that extend out past the orbit of Neptune. If you brought Pluto into the inner Solar System, it would start to act like a comet – blasting out gas and particles from the solar wind. It’s a good thing Pluto is in the cold, dark outer Solar System, far away from the Sun.

So, if it would act like a comet, what is Pluto built of, and how do we even know? Pluto is so small and dim that only the largest telescopes can see it. To even see with your own eyes, you want a 30 cm (12 inch) telescope – and then you’ll only see a dot.

Astronomers using the world’s biggest telescopes, including the Hubble Space Telescope see a much better view. By using a technique called spectroscopy, astronomers can analyze the details about Pluto’s surface. The current thinking is that it’s composed of more than 98% nitrogen ice, with traces of methane and carbon monoxide.

The limits of telescope technology mean that we can’t get a better view of Pluto’s surface. But NASA’s New Horizons spacecraft is making the journey to Pluto, and will make a flyby in 2015. At that point, it will fly within 10,000 km of Pluto’s surface and send back images that show features as small as 1.6 km across. This will be a tremendous improvement over our current understanding of Pluto.

But what’s inside?

Planetary scientists have calculated Pluto’s density at between 1.8 and 2.1 g/cm3. From this density, they have calculated that its interior is probably 50-70% rock and 30-50% ice. Decaying radioactive elements inside Pluto would heat the interior of the dwarf planet, allowing the rock and ice to move around. At this point, the interior of Pluto is probably a rocky core surrounded by a shell of ice. If the radioactive elements are still decaying today, they could heat Pluto up enough that it has an interior liquid ocean, like Jupiter’s moon Europa.

The surface of Pluto is a thin layer of nitrogen, methane and carbon monoxide. When Pluto is at its closest to the Sun, this material evaporates, and forms an atmosphere around the dwarf planet. And then, when it’s further from the Sun, and cooler, this atmosphere freezes back down onto the surface.

Here are some nice Pluto images.

Source: NASA

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 Ian O'Neill

Soyuz Hard Landing: The Facts

Rescue helicopters next to the askew Soyuz on Saturday (Shamil Zhumatov)

Now the dust has settled news sources appear to be coherently reporting the events that unfolded early Saturday morning. As several readers have shown concern that reporting on the Soyuz ballistic re-entry makes us opposed to Russian efforts in space, I hope these points clearly show that this is not the case. In actuality, without the Russian Soyuz fleet of personnel/cargo supply spacecraft, much of the international community’s plans for space would be scuppered. So, what do we know happened after the Soyuz descent capsule undocked from the space station in the early hours of Saturday?

Well, most of the original reports appeared to be fairly accurate. From Tuesday, it seems that much of the reports from news agencies in the US and UK have been corroborated with the Russian news agency Interfax. On April 23rd, William Gerstenmaier, NASA’s associate administrator for space operations, gave a statement as to what went wrong. So here’s what we know:

  • Due to a technical fault, and not crew error, the Soyuz descent capsule did not separate from its propulsion module as planned. The explosive bolts used to separate the Soyuz modules before re-entry didn’t work on time. This may have resulted in the descent module and propulsion module hitting the atmosphere before they separated.
  • It is not clear if the modules were separated late by the explosive bolts, or if they were pulled apart (Gerstenmaier points out that they may break apart on re-entry, allowing the descent module and crew to make an emergency landing). Either way, a “ballistic re-entry” (rather than the planned guided re-entry) was the result. Ballistic re-entry was likened by Gerstenmaier to, “a bullet out of a rifle,” before the parachutes opened.
  • The crew experienced forces up to 8.2 times greater than Earth’s gravity.
  • The re-entry caused damage to the capsule escape hatch due to the angle of descent. Areas other than the heat shield had been burnt. The communications antenna was lost at this stage.
  • NASA confirms there was no communication with the capsule until cosmonaut Colonel Yuri Malenchenko was able to get free of the cabin and use a satellite phone to contact mission control. This was 30 minutes after touch-down.

The Soyuz landing site (Shamil Zhumatov)

So it appears the emergency landing was actually very successful. As pointed out by Gerstenmaier the Soyuz spacecraft design has “an inherent reliability in the system.” After all, the original manned Soyuz spacecraft design was launched in 1967, and since then there have been 99 missions (11 since 2002). It is a rugged and highly dependable space vehicle, and in 2010 when the Space Shuttle is retired we will need Soyuz to supply the space station and transport personnel. The Orion space ship isn’t scheduled to launch until 2015, so there is a five year gap that will need to be filled. NASA is looking into commercial options, but the tried, tested and reliable Soyuz remains the best option.

However, the way this incident was handled is highly worrying. I just hope that a thorough investigation into the technical fault and the way Russian officials covered up events is carried out, so future re-entries can be better managed.

In case you missed the Universe Today coverage of this story:

Sources: McClatchy
, Orlando Sentinel

Posted on by Matt Williams

Universe Today’s Guide to Space

Credit: Pablo Carlos Budassi

The Solar System:

Outer Space:

Space Exploration:

History of Space Exploration:

Famous Scientists:

Einstein Lecturing

Famous Astronauts:

Apollo 11 Crew Photo. Credit: NASA

Astronomy Jargon:

Astronomy & Cosmology:

Earth Sciences:

SETI:

Messier Objects:

Constellations:

Telescopes:

This artist’s rendering shows the Extremely Large Telescope in operation on Cerro Armazones in northern Chile. The telescope is shown using lasers to create artificial stars high in the atmosphere. Image: ESO/E-ELT

Image Credits:

Posted on by Tammy Plotner

Nova Sagittarius 2008 UPDATE

NOVA SGR 2008 - Joseph Brimacombe

Since the initial alert for the latest nova in Sagittarius, folks the world over have been anxious for darkness to arrive and their chance at spotting this cosmic wonder firsthand. Thanks to our good friends at Macedon Ranges Observatory, Universe Today readers are about to see the latest nova in Sagittarius revealed and learn just what is a nova.

One thing is certain, both professional and amateur astronomers have something in common – curiosity. Unfortunately, because many of us live where skies seem to be perpetually cloudy or don’t always have the equipment to view a late breaking astronomy alert object, it becomes even more imperative to be able to call upon others in different regions of the world. It certainly is a true pleasure to have friends down under! So now that we see it… What is a nova?

The word nova is Latin for “new star”. Astronomers assign the term nova to stars that have a rapid increase in brightness. These stars are usually far too dim to be seen unaided and may often become the brightest object – besides the Sun and Moon – in the sky!

Novae themselves are stars that have been quiet for many years, and suddenly decided to reignite their nuclear fusion process. All stars have fusion occurring in their core – processing hydrogen into helium and releasing energy. When this fuel is expended, stars like our sun simply shed their outer layer and continue on as small, hot, white dwarf stars. They are basically dead… Their fuel gone.

Unlike our own Sun, most stars are a binary system – two stars that closely orbit each other. If one of these stars should happen to be a white dwarf and the other starts to evolve into a red giant, the white dwarf can begin attracting gas towards itself by means of gravity. What type of gas? Hydrogen! When the hydrogen stolen from the red giant reaches the surface of the incredibly hot white dwarf, it rapidly ignites. What’s born is an incredibly huge nuclear explosion on the white dwarf’s surface and we see it as a nova!

NOVA SGR 2008 24April - Joseph Brimacombe

Using a 12″ Ritchey Chretien Optical Systems telescope, Joe Brimacombe set to work imaging the latest nova for us to see. By comparing this photo with the 19 April Sagittarius Image you can see how quickly the white dwarf ignited!

Nova Sgr 19April2008 Joseph Brimacombe Image details are as follows: STL11000 camera; BRC 250; image scale 1.46 asec/px; image is 97 amin across; nova is centre star; stack 6 x 300 Ha; false colour.

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.