Fly Over the Columbia Hills at APOD

If you haven’t yet discovered Astronomy Picture of the Day, its an absolutely wonderful site that provides a different image every day of our universe, with explanations written by two professional astronomers, Robert Nemiroff and Jerry Bonnell. Today’s APOD post is not a picture, however, but a movie. Combining data taken from the Mars Reconnaissance Orbiter and the Mars Rover Spirit, Doug Ellison from UnmannedSpaceflight.com created a movie that simulates a fly-over of the Columbia Hills region on Mars. Of course, the Hills were named in memory of the astronauts who died in the Columbia space shuttle accident in February 2003.

In the movie you see the rippled sand on the sides of the Hills, the peak on Husband Hill where Spirit triumphantly climbed and surveyed the amazing view, and a white-colored area back on lower ground called Home Plate that Spirit has been studying for a couple of months now. Spirit herself makes a cameo in the video, too. It’s just great fun to watch.

Well, instead just reading about it, go visit APOD to watch the movie. And stay and browse awhile: APOD boasts the largest collection of annotated astronomical images on the internet.

Venus’ Orbit Around the Sun

The orbit of Venus is the most circular in the entire Solar System. In mathematical terms, the eccentricity of Venus is less than 0.01. A year on Venus lasts 223 days.

As Venus travels around the Sun, it ranges in distance from 107 million km to 109 million km. The average distance is 108 million km. This is 72% the distance of Earth to the Sun.

Venus can get as close as 40 million km from the Earth. This is called an inferior conjunction every 584 days, on average.

One of the most unusual things about Venus is that it rotates backwards from the rest of the planets in the Solar System. Seen from above, all of the planets rotate counter-clockwise, but Venus turns clockwise. Of course, Venus orbits so slowly that its day is actually longer than its year. A day on Venus lasts 243 Earth days, while its year is 224.7 Earth days.

Does Venus Have Volcanoes?

Our planet is an active world geologically. We have volcanoes constantly erupting across the planet, especially in the regions where plate tectonics are most active. Wherever one plate is sliding against another plate, or one is passing underneath another, you can expect to see volcanoes erupting.

Since Venus is such a hellish world, with incredibly hot temperatures and hot pressures, does Venus have volcanoes?

Venus certainly did have volcanoes in the past. Planetary scientists have identified more than 1,600 major volcanoes or volcanic features on Venus. And there almost too many smaller ones to count. So Venus did have volcanoes.

But does Venus have any volcanoes right now? Unfortunately, we just don’t have enough data to go on. Venus is shrouded in thick clouds of carbon dioxide in its atmosphere, so you can’t have an orbiter easily take photographs of the planet’s surface.

There is no water on the surface of Venus, and scientists know that the planet has no plate tectonics, like we have here on Earth. There are no continents. And so Venus doesn’t have the same regions of volcanism as we have on Earth.

So right now, scientists have no idea if there are volcanoes on Venus. There could be a few spotty regions across the planet, where there is some activity, but none have been seen erupting in the present.

Strange, Super-Sized Pulsar Stumps Scientists

Astronomers have discovered a fast-spinning, super-sized pulsar in a stretched-out orbit around an apparent Sun-like star. This combination (as well as that many hyphenated words in one sentence) has never seen before, and astronomers are puzzled about how this bizarre system developed. “Our ideas about how the fastest-spinning pulsars are produced do not predict either the kind of orbit or the type of companion star this one has,” said David Champion of the Australia Telescope National Facility. “We have to come up with some new scenarios to explain this weird pair.”

Pulsar J1903+0327, a rotating neutron star, is unusually massive for its type. It spins on its axis 465 times every second, while typical pulsars spin a few times a second. Located nearly 21,000 light-years from Earth, its elongated orbit takes it around its companion star once every 95 days. And the companion star is quite unusual as well: many pulsars pair up with a white dwarf star or another neutron star, but infrared images of the system show a Sun-like star along with the pulsar.

“This combination of properties is unprecedented. Not only does it require us to figure out how this system was produced, but the large mass may help us understand how matter behaves at extremely high densities,” said Scott Ransom of the National Radio Astronomy Observatory.

The image above shows the size and shape of Earth’s orbit around the sun compared to the orbits of Pulsar J1903+0327 and its possible Sun-like companion star. The sizes of the Sun and the possible companion star have been exaggerated by a factor of about 10, while that of the Earth has been exaggerated by a factor of about 1000. The pulsar, with its magnetic field and beams of radiation, is too large by a factor of about 100,000.

This pulsar was first detected in 2006 with the Arecibo radio telescope in Puerto Rico, with subsequent observations by the Robert C. Byrd Green Bank Telescope (GBT) in West Virginia, the Westerbork radio telescope in the Netherlands, and the Gemini North optical telescope in Hawaii.

It’s possible that the pulsar may be part of a triple, not a double, star system. In this case, the pulsar’s 95-day orbit is around a neutron star or white dwarf that’s not been detected yet, not the Sun-like star seen in the infrared image. The Sun-like star would then be in a more-distant orbit around the pulsar and its close companion. But this, too would be highly unusual.

“We’ve found about 50 pulsars in binary systems. We may now have found our first pulsar in a stellar triple system,” Ransom said.

Further studies are underway to get a better understanding of what seems to be a highly unusual system.

“This is a fascinating object that has a lot to teach us about physics. It’s going to be exciting to peel away the mystery of how this thing came to be,” Champion said.

Original News Source: National Radio Astronomy Observatory

Does Venus Have Rings?

Unfortunately, Venus doesn’t have rings. It also doesn’t have any moons; although, Venus might have had a moon in the past, but it probably crashed back into the planet billions of years ago.

For a planet to have rings, it must have formed further out in the Solar System, where water ice would be able to freeze into chunks of ice. It’s too warm around Venus, so that any water would be a gas or liquid. It would either collect into oceans, like Earth, or be pushed out into deeper space by the Sun’s solar wind.

Another way that planets can have rings is when micrometeoroids smash into a small moon. If the moon is really small, like Pluto’s moon Nix, material ejected from the meteoroid impact will just float off into space and form a ring around the planet. There are several moons around Saturn which create rings in this way, and scientists think that Pluto’s moons might form rings in the same way.

Sorry, no rings for Venus.

Does Pluto Have Rings?

Saturn has rings and Jupiter has rings. Does Pluto have rings? Astronomers have no idea. Pluto is so far away that it’s impossible to get a clear view of Pluto from here on Earth.

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But scientists think that it’s possible that Pluto does have rings. This idea comes from the fact that Pluto has two tiny moons, Nix and Hydra. They’re just a few km across, and have very little gravity. So any micrometeoroid impacts on these moons will kick up material into orbit around Pluto.

Instead of falling back down onto the moons, this impact material would drift into rings around Pluto. Astronomers think it could actually survive for up to 100,000 years. This is a similar process that creates some of the rings around Saturn and Jupiter.

If this is true, it would constitute the first set of rings around a solid object (in this case a dwarf planet), rather than a gas giant planet.

When NASA’s New Horizons mission arrives at Pluto in 2015, it might be able to detect these faint rings, and confirm the theory.

How Far is Pluto from Earth?

The planet Earth has a slightly eccentric orbit. This means that its distance from the Sun can vary slightly as the Earth travels an elliptical path around the Sun. Pluto has an extremely elliptical orbit, varying its distance dramatically from the Sun dramatically.

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So the closest distance between the Earth and Pluto occurs when Earth is at its most distant from the Sun, and Pluto is at its closest. And the Sun, Earth and Pluto are lined up in a perfect line. When this happens, Pluto and Earth would be separated by 4.2 billion km.

At their most distant, Earth would be at its furthest at the opposite side of the Sun from Pluto. At this point, Earth and Pluto would be separated by 7.5 billion km.

And so, the distance from Earth to Pluto ranges between these two distances.

Weekend SkyWatcher’s Forecast – May 16-18, 2008

Sinus Iridum by Wes Higgins

“Everybody dancing in the moonlight… Dancing in the moonlight… Everybody feeling warm and bright… It’s such a fine and natural sight… Everybody dancing in the moonlight.” Oh! Greetings, fellow SkyWatchers! Pardon me while I celebrate the return of Spring and enjoy viewing the Moon. This weekend will be a terrific time for you to dance, too. Talk a waltz around the “Bay of Rainbows” as you view Sinus Iridum and enjoy the cool blues with Spica. You’ll be seeing double before the weekend is out. Time to dust off the optics and turn and eye to the sky, because… Here’s what’s up!

Friday, May 16, 2008 – Tonight would be a wonderful opportunity for Moongazers to return to the surface and have a look at the peaceful Sinus Iridum area. If you’ve been clouded out before, be sure to have a look for the telescopic Lunar Club challenges Promontoriums Heraclides and LaPlace. What other craters can you discover in the area?

Palomar Observatory, courtesy of Caltech
If you’re up for a bit more of a challenge, then let’s head about 59 light-years away for star 70, in Virgo. You’ll find it located about six degrees northeast of Eta (RA 13 28 25 Dec +13 46 43) and right in the corner of the Coma-Boötes-Virgo border. So what’s so special about this G-type, very normal-looking, 5th magnitude star?

It’s a star that has a planet.

Long believed to be a spectroscopic binary because of its 117 day shift in color, closer inspection has revealed that 70 Virginis actually has a companion planet. Roughly seven times larger than Jupiter and orbiting no further away than Mercury from its cooler-than-Sol parent star, 70 Virginis B just might well be a planet cool enough to support water in its liquid form. How “cool” is that? Try about 85 degrees Celsius…

Saturday, May 17, 2008 – Today in 1835, J. Norman Lockyer was born. While that name might not stand out, Lockyer was the first to note previously unknown absorption lines while making visual spectroscopic studies of the Sun in 1868. Little did he know at the time, he had correctly identified the second most abundant element in our universe – helium – an element not discovered on Earth until 1891! Also known as the “Father of Archeoastronomy,” Sir Lockyer was one of the first to make the astronomical connection with ancient structures such as Stonehenge and the Egyptian pyramids. (As a curious note, 14 years after Lockyer’s notation of helium, a Sun-grazing comet made its appearance in photographs of the solar corona taken during a total eclipse in 1882… It hasn’t been seen since.)

Spica by John ChumackIf you would like to see a helium-rich star, look no further tonight than Alpha Virginis – Spica. You can’t miss it because it’s so near the Moon! As the sixteenth brightest star in the sky, this brilliant blue-white “youngster” appears to be about 275 light-years away and is about 2300 times brighter than our own Sun. Although we cannot see it visually, Spica is a double star. Its spectroscopic companion is roughly half its size and is also rich in helium.

Crater Copernicus by Wes HigginsSunday, May 18, 2008 – On this day in 1910, Comet Halley transited the Sun, but could not be detected visually. Since the beginning of astronomical observation, transits, eclipses and occultations have provided science with some very accurate determinations of size. Since Halley could not be spotted against the solar surface, we knew almost a century ago that the nucleus had to be smaller than about 100 kilometers. To get a rough idea of this size, take a look at crater Copernicus about midway along the western hemisphere of the Moon. What’s its diameter? Oh, about the same size as a certain comet!

Now let’s have a look at a very bright and changeable lunar feature which is often overlooked. Starting with the great grey oval of Grimaldi, let your eyes slide along the terminator toward the south until you encounter the bright crater Byrgius. Named for Joost Bürgi, who made a sextant for Tycho Brahe, this “seen on the curve” crater is really quite large with a diameter of 87 kilometers. Perhaps its most interesting feature is the high-albedo Byrgius A, which sits along its eastern wall line and produces a wonderfully bright ray system. While it’s noted as a Lunar Club II challenge, it’s also a great crater to help add to your knowledge of selenography!

It’s time to add to our double star list as we hunt down Zeta Boötes located about seven degrees southeast of Arcturus (RA 14 41 08 Dec +13 43 42). This is a delightful multiple star system for even small telescopes – but not an easy one. The Zeta pairing has an extremely elliptical orbit: the distance between the stars varies from as little as the Earth-Sun distance to as much as 1.5 times the radius of Pluto’s orbit!

Another great target for a bright night is Delta Corvi (RA 12 29 51 Dec -16 30 55). 125 light-years away, it displays a yellowish-colored primary and a slightly blue secondary that’s an easily split pair in any telescope, and a nice visual double with Eta in binoculars. Use low power and see if you can frame this bright grouping of stars in the same eyepiece field.

Wising you good luck, clear skies and a wonderful weekend! 😉

This week’s awesome photos are of Sinus Iridum and Copernicus by the one and only Wes Higgins, 70 Virginis – Credit: Palomar Observatory, courtesy of Caltech and Alpha Virginis: Spica, by none other than the incredibly talented John Chumack. Spectacular!

Surface of Venus

The "impact farm:, an area on Venus marked by impact craters and volcanic activity. Credit: NASA/JPL

The surface of Venus is a hellish place, with vast regions shaped by volcanic activity. In fact, Venus has many more volcanoes than Earth. It has more than 150 regions across the planet shaped by volcanoes.

And from this, you would think that Venus is more volcanic than Earth, but actually, it’s just that the regions of volcanic activity weren’t covered up as they have been here on Earth. The surface of Earth is constantly reshaped by tectonic activity, where plates on the crust of the planet float atop a layer of magma. These plates can slide underneath one another, and any features on the surface are destroyed.

For some reason, plate tectonics on Venus stopped billions of years ago. Planetary scientists think that the high temperatures on Venus shut down the cycle of plate tectonics. Volcanic features created on the planet billions of years ago are still visible, while they would have been obscured long ago on Earth.

Scientists think there is still active volcanism on Venus.

There are more than 1,000 impact craters on Venus, distributed across the planet. While craters are eroded here on Earth, they’re still in pristine condition on Venus. The craters range in size from 3 km to 280 km in diameter.