Tag Archives: astronomy

Pluto: The former planet still fascinates and intrigues

Pluto with moons:  Charon, Nix and Hydra

Pluto with moons: Charon, Nix and Hydra

Fun Facts About Pluto


1. Pluto has an atmosphere

Even though Pluto’s average temperature averages a mere 44 degrees above absolute zero, the dwarf planet has an atmosphere. Not an atmosphere as we know it, but an atmosphere, none the less.

It was first discovered back in 1985, when astronomers watched as Pluto passed in front of a star. They were able to calculate a slight dimming as its atmosphere passed in front of the star, before Pluto itself blocked the star entirely. From those observations, they were able to calculate that it has a thin envelope of nitrogen, methane and carbon dioxide.

As Pluto moves away from the Sun, this atmosphere gets so cold that it freezes onto the surface. And then as the dwarf planet warms again, the atmosphere evaporates again, forming a gas around it.

2. Pluto has 3 moons

You might have heard that Pluto has a large moon called Charon, but did you know that it actually has 3 moons in total. Charon is the large one, with a mass of roughly half that of Pluto’s.

Two additional moons, Nix and Hydra, were discovered by astronomers using the Hubble Space Telescope on May 15, 2005. They were originally called S/2005 P1 and S/2005 P2, and then given their final names on June 21, 2006.

They took a long time to discover because they’re so tiny. Nix is only 46 km across, while Hydra is 61 km across.

3. Pluto hasn’t cleared out its orbit

Although Pluto orbits the Sun and it’s round, it’s not a planet. And that’s because Pluto hasn’t cleared out its orbit of material. This was the reason that the International Astronomical Union chose to demote it from planet to dwarf planet in 2006.

Just to give you an idea, if you added up the mass of all the other objects in Pluto’s orbit, Pluto’s mass would only be a tiny fraction of that total. In fact, it would only be 0.07 times as massive as everything else. For comparison, if you did the same thing with all the other material in the Earth’s orbit, our planet would be 1.5 million times as massive.

And that’s why Pluto’s not a planet.

4. Pluto is actually a binary system

You’d think that Charon orbits Pluto, but actually, Pluto and Charon orbit a common point in space. In the case of the Earth and the Moon, we actually orbit a common point, but that spot exists inside the Earth. In the case of Pluto and Charon, however, that common point is above the surface of Pluto.

Before Pluto was downgraded to a dwarf planet, astronomers were thinking of classifying it as a binary planet system. And then as a binary dwarf planet system. Perhaps that will help it recover some of its lost glory.

5. Pluto is named after a god, not a dog

If you think Pluto is named after a Disney character, you’re wrong. It’s actually named after the Roman god of the underworld. And Charon is the ferryman who carries souls across the river Styx.

When it was first discovered, Pluto was just given the name Planet X, but then the discoverers needed to come up with something better and more permanent. The name Pluto was suggested by Venetia Burney, an 11-year old school girl in Oxford, England. She thought it was a good name for such a cold, dark world. It was passed along to the discoverers and they liked it enough to make it official.

6. Pluto can be closer than Neptune

For most of its orbit, Pluto is more distant than Neptune, reaching out as far as 49 astronomical units (49 times the distance from the Earth to the Sun). But it has such an eccentric, elliptical orbit that it gets much closer, reaching a mere 29 AU. And during that time, it’s actually orbiting within the orbit of Neptune. The last time Pluto and Neptune made this switch was between February 7, 1979 and February 11, 1999. And give it another couple of hundred years and it’ll happen again.

7. Pluto is smaller than any planet, and even 7 moons

Pluto is small. How small? Astronomers recently calculated that its mass is 1.31 x 1022 kg (less than 0.24% the mass of Earth). And its diameter is only 2,390 km across.

At this point, it’s smaller than Mercury, and seven other moons including: Ganymede, Titan, Callisto, Io, Earth’s Moon, Europa, and Triton.

And now astronomers know that it’s even smaller than the recently discovered dwarf planet Eris. Here’s more information about how big Pluto is.

8. If it were closer to the Sun, Pluto would be a comet

Although this isn’t officially a reason for losing its planet status, Pluto wouldn’t last long if it got much closer to the Sun. It’s comprised of about half rock and half ice. This is a similar ratio to many rocky comets in the Solar System.

If you could somehow bring Pluto closer to the Sun, it would sprout a tail, becoming a spectacular comet. And over millions of years, the solar wind would blast away its icy structure, causing it to lose mass.

It’s lucky Pluto lives in such a cold, dark part of the Solar System.

9. Charon might have geysers

In the last few years, astronomers have discovered that several objects in the Solar System have ice geysers, including Saturn’s moon Enceladus, and maybe several others as well. But Pluto’s moon Charon could have this happening too.

Astronomers using the Gemini Observatory in Mauna Kea in Hawaii recently turned up evidence that geysers on Charon are spreading ammonia hydrates and water crystals across the surface of the moon.

Is this really happening? We’ll know soon, because… here’s the last Pluto fact.

10. There’s a spacecraft going to Pluto right now

NASA’s New Horizons spacecraft is making its way to Pluto right now. The spacecraft launched in 2005, and its expected to reach the dwarf planet in 2015. It will pass right through the system, imaging the surface of Pluto and its moons, and finally answering questions that have puzzled astronomers for nearly a hundred years.


Special thanks to www.universetoday.com

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Crab Nebula: One of Mankind’s Earliest Celestial Discoveries

The Crab Nebula

The Crab Nebula as taken by the Hubble Space Telescope (HST)

Fun Facts About The Crab Nebula

  • A nebula is a mixture of hot gas, dust and simple elements like hydrogen and helium.

    The Crab Nebula (listed as "Supernova Remnant") in the constellation of Taurus

    The Crab Nebula (listed as "Supernova Remnant") in Taurus

  • The Crab Nebula is approximately 6,500 light-years from Earth in the constellation Taurus.
  • The nebula itself is 10 light-years in diameter. To put that into perspective, if the Sun were the size of a basketball, the Crab Nebula would be the size of planet Earth.
  • The Crab Nebula has earned its place in history by being discovered on July 5, 1054 by early Chinese and Arab astronomers.
  • The Crab Nebula formed in a supernova about the time that humans were just getting a grasp on farming and maybe some bronze working, call it 5,500 BCA.
  • The light from the event didn’t reach the Earth until 1054.
  • The Nebula, as we see it today, was discovered independently by John Bevis in 1731, and again by Charles Messier in 1758. It was, in fact, the first object that Messier catalogued in his search for “comet like objects” (though most of them were not comets at all), and therefore it is also referred to as M1.Historical records from 1054 described the supernova that created the Crab Nebula as a celestial event that was so bright that it was seen in the day time. It was easily the brightest object in the sky, besides the Sun and Moon, for several months.
  • The Crab Nebula got its most familiar name in 1840 when the William Parsons, the Third Earl of Rosse, using a 36-inch telescope, created a drawing of the nebula that he thought looked like a crab. With the 36-inch telescope he was not able to fully resolve the filaments, the colored web of hot gas that permeates the nebula.
  • In 1848 Parsons observed the object again, but with a larger 72-inch telescope which allowed him to see greater detail. And although he noted that his earlier drawings were not representative of the true structure of the nebula, the name Crab Nebula had already taken hold.

    X-Ray Image of the Crab Nebula

    X-Ray Image of the Crab Nebula

  • The Crab is part of a class of objects called Super Nova Remnants (SNRs). As the name suggests SNRs are the result of a large star going through a phase of its evolution known as a supernova.
  • Supernovas occur when stars no longer have enough fuel to keep from collapsing onto themselves and they explode in a violent burst of energy.
  • When the star that is currently the Crab Nebula exploded it was not large enough to create a black hole, but it was big enough that the core that remained was so densely packed by the explosion that it was made of Neutronium, which is matter so compressed that neutrons are packed side by side with no room for electrons. It is incredibly dense.
  • The outer part of the star is driven into space, forming the “remnant” that we see today. The inner part of the star, known as the core, contracts due to gravity and forms a new type of object called a neutron star.
  • The neutron star that remains after a supernova is extremely small, usually just 10 to 15 miles across. But it is extremely dense. It is so dense, in fact, that if you had a can of soup filled with neutron star material, it would have about the same mass as the Moon.

    The Crab Nebula Pulsar

    The Crab Nebula Pulsar

  • The Crab’s neutron star, roughly in the center of the nebula, spins at a very high rate, completing about 30 revolutions every second. Rotating neutron stars, like the Crab’s, are called pulsars (derived from the words PULSating stARS).
  • The pulsar inside the crab nebula is one of the most powerful ever observed. It injects so much energy into the nebula, we can detect light in virtually every wavelength from low energy radio photons to the highest energy gamma-rays.
    Special thanks to www.about.com and my.firedoglake.com

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