Posted on by Jason Major

New Comet Discovered by Amateur Astronomer

Image of Comet C/2012 C2 (Bruenjes) made from ten 60 sec. exposures on Feb. 11, 2012. (Fred Bruenjes)

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“Friday, February 10th 2012 just felt like the perfect night for a comet to be discovered by an amateur astronomer,” writes Fred Bruenjes on his astronomy blog. And, this past Friday night, that’s exactly what Fred did.

Here’s how he did it:

Using custom-written software to operate a 14″ Meade LX200GPS telescope in his self-built observatory in Warrensburg, Missouri, Fred set his system up to capture images of the sky on that cold evening, not allowing himself to be chased inside by the low temperatures or the bright, rising moon. After some technical difficulties with his dSLR, Fred managed to acquire some quality images. While making a cursory look through the blink data, Fred was surprised to spot a faint burry object visible moving across three frames. A check of online databases of known objects brought up no positive hits — this was something that hadn’t been seen before.

Raw-color discovery image. (Fred Bruenjes)

Fred describes the “eureka” moment on his blog:

A check of known objects in the region had a lot of results in the area, but all were moving eastward while my fuzzy was moving westward. Rocks don’t make U-turns. This was really getting exciting. I had Jen, my better half, an accomplished astro imager, take a look at the images and before I could point out the faint smudge she exclaimed “That’s a comet!”

Still, Fred notes, “it wasn’t a slam-dunk.” The images were faint and there could have been other causes of blurry spots in digital images. But a check of the raw color data revealed a greenish coloration to the object’s glow, which is indicative of cyanogen and carbon emission — typical hallmarks of comets. “Very encouraging,” Fred added.

Another night’s observation was needed. If it was a comet, it would appear again along its expected trajectory. Of course, with an unidentified comet there would be no known orbit, so Fred had to manually extrapolate its position. When he trained his telescope onto his calculated coordinates the following evening and began taking images, there it was… the same faint, fuzzy green blur from the previous night, slowly appearing in the darkening sky right where it should be.

“Oh. Wow. It was dead nuts at where it was supposed to be,” Fred writes. “Wow. This thing is for real! It’s at about this time that it begins to sink in that a lifelong quest has just been fulfilled. I just crossed another thing off the bucket list!”

Fred spent the next hour gathering images to send in to the IAU’s Minor Planet Center, in the hopes of having the object cataloged so that others could locate and observe it. He didn’t have to wait long; within five minutes the object was listed on the Near-Earth Object Confirmation Page, and dubbed C/2012 C2 (Bruenjes), in honor of its discoverer.

Now that’s just got to feel good.

Comet Bruenjes is an NEO currently about 0.555 AU away from Earth. Its exact size and orbital period isn’t known, and it may even be a returning comet or piece from a larger one… the official report isn’t out yet. It appears to have a fairly inclined orbit relative to the ecliptic, based on the current diagram created by JPL’s Small-Body Database.

Currently plotted orbit of C/2012 C2 (Bruenjes) (NASA/JPL)

The comet’s total magnitude is 16.6, so it is dim and not visible to the naked eye. Fred told Universe Today in an email: “it’s in the constellation Aries, about six degrees north of Jupiter. Just after sunset in the Northern hemisphere it’s high in the southwest, nearly overhead.”

Stay tuned for more updated information on this newly-discovered member of our solar system. And congratulations to Fred Bruenjes, comet-hunter extraordinaire!

Read Fred’s full story on his astronomy site here.

Images © 2012 Manfred Bruenjes. All rights reserved. Used with permission.

 

Posted on by Jason Major

Asteroid To Make Closest Approach Since 1975

Asteroid 433 Eros, seen by NASA's NEAR spacecraft on Feb. 29, 2000. (NASA/JPL/JHUAPL)

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On Tuesday, January 31, asteroid 433 Eros will come closer to Earth than it has in 37 years, traveling across the night sky in the constellations Leo, Sextans and Hydra. At its closest pass of 16.6 million miles (26.7 million km) the relatively bright 21-mile (34-km) -wide asteroid will be visible with even modest backyard telescopes, approaching magnitude 8, possibly even 7. It hasn’t come this close since 1975, and won’t do so again until 2056!

433 Eros is an S-type asteroid, signifying a composition of magnesium silicates and iron. S-types make up about 17 percent of known asteroids and are some of the brightest, with albedos (reflectivity) in the range of 0.10 – 0.22. S-type asteroids are most common in the inner asteroid belt and, as in the case of Eros, can even pass within the orbit of Mars.

Occasionally Eros’ orbit brings it close enough to Earth that it can be spotted with amateur telescopes. 2012 will be one of those times.

Eros was discovered on August 13, 1898, by astronomers Carl Gustav Witt in Berlin and Auguste Charlois in Nice. When Eros’ orbit was calculated it was seen to be an elongated oval that brought it within the orbit of Mars. This allowed for good observations of the bright asteroid, and eventually led to more accurate estimates of the distance from Earth to the Sun.

In February 2000 NASA’s NEAR Shoemaker spacecraft approached Eros, established orbit and made a soft landing on its surface, the first mission ever to do so. While in orbit NEAR took over 160,000 images of Eros’ surface, identifying over 100,000 craters, a million house-sized boulders (give or take a few) and helped researchers conclude that the cashew-shaped Eros is a solid object rather than a “rubble pile” held together by gravity.

View NEAR images of Eros’ surface.

Studying pristine objects like Eros gives insight into the earliest days of our solar system, and also allows scientists to better understand asteroid compositions… which is invaluable information when deciding how best to avoid any potential future impacts.

Orbit of 433 Eros for Jan. 31, 2012

Although Eros will be making a “close” approach to Earth on Jan. 31/Feb. 1, there is no danger of a collision. It will still remain at a very respectable distance of about 16.6 million miles (26.7 million km), or 0.178 AU. This is over 80 times the distance of the much smaller 2005 YU55, which safely passed within a lunar orbit radius on November 8, 2011.

If you do want to try viewing 433 Eros as it passes, you can find a diagram charting its path from Sky and Telescope here. According to the Sydney Observatory’s website “the coordinates on 31 January (from the BAA 2012 Handbook) are 10 hours 33 minutes 19.0 seconds RA and -4° 48’ 23” declination. On 10 February the RA is 10 hours 20 minutes 27.6 seconds and the declination is -14° 38’ 49 seconds.”

Also there’s an updated chart on Heavens Above showing Eros’ current position.

Eros should remain visible up until Feb. 10.

Thanks to Skyscrapers, Inc., for a report on 433 Eros by Glenn Chaple. Skyscrapers, Inc. is an amateur astronomy society in Rhode Island that operates the Seagrave Observatory, whose centerpiece is a beautiful 8 1/4″ Alvan Clark telescope built in 1878. I saw Halley’s Comet through that telescope in 1986 and have been hooked on astronomy ever since.

Posted on by Jason Major

Does Earth Have Many Tiny Moons?

This radar image of asteroid 2005 YU55 was obtained on Nov. 7, 2011. Credit: NASA/JPL/Caltech.

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Look up in a clear night sky. How many moons do you see? Chances are, you’re only going to count to one. Admittedly, if you count any higher and you’re not alone, you may get some funny looks cast in your direction. But even though you may not be able to actually see them, there may very well be more moons out there orbiting our planet.

For the time being, anyway.

Today, Earth has one major moon in orbit around it. (Technically the Earth-Moon system orbits around a common center of gravity, called the barycenter, but that’s splitting hairs for the purpose of this story.) At one time Earth may have had two large moons until the smaller eventually collided into the larger, creating the rugged lump we now call the farside highlands. But, that was 4 billion years ago and again not what’s being referred to here.

Right now, at his moment, Earth may very well have more than the one moon we see in the night sky. Surprise.

Of course, it would be a very small moon. Perhaps no more than a meter across. But a moon nonetheless. And there could even be others – many others – much smaller than that. Little bits of solar system leftovers, orbiting our planet even farther out than the Moon we all know and love, coming and going in short-lived flings with Earth without anyone even knowing.

This is what has been suggested by researcher Mikael Granvik of the University of Helsinki in Finland. He and his colleagues have created computer simulations of asteroids believed to be occupying the inner solar system, and what the chances are that any number of them could be captured into Earth orbit at any given time.

Orbit of 2006 RH120, a confirmed TCO identified in 2006.

The team’s results, posted Dec. 20 in the science journal Icarus, claim it’s very likely that small asteroids would be temporarily captured into orbit (becoming TCOs, or temporarily captured objects) on a regular basis, each spending about nine months in up to three revolutions around Earth before heading off again.

Some objects, though, might hang around even longer… in the team’s simulations one TCO remained in orbit for 900 years.

“There are lots of asteroids in the solar system, so chances for the Earth to capture one at any time is, in a sense, not surprising,” said co-author Jeremie Vauballion, an astronomer at the Paris Observatory.

In fact, the team suspects that there’s most likely a TCO out there right now, perhaps a meter or so wide, orbiting between 5 and 10 times the distance between Earth and the Moon. And there could be a thousand smaller ones as well, up to 10 centimeters wide.

So if these moons are indeed out there, why don’t we know about them?

Put simply, they are too small, too far, and too dark.

At that distance an object the size of a writing desk is virtually undetectable with the instruments we have now.. especially if we don’t even know exactly where to look. But in the future the Large Synoptic Survey Telescope (LSST) may, once completed, be able to spot these tiny satellites with its 3200-megapixel camera.

Once spotted, TCOs could become targets of exploration. After all, they are asteroids that have come to us, which would make investigation all the easier – not to mention cheaper – much more so than traveling to and back from the main asteroid belt.

“The price of the mission would actually be pretty small,” Granvik said. And that, of course, makes the chances of such a mission getting approved all the better.

Read more on David Shiga’s article on New Scientist here.

The team’s published paper can be found here.

Posted on by Mike Simonsen

Venus Has a Moon?

Venusian quasi-satellite 2002 VE68. Illustration: NASA/JPL/Caltech

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Astronomers have been busy trying to determine the spin period and composition of Venus’ moon. December 8, 2010, results were announced by JPL/Caltech scientists, led by Michael Hicks.

“Wait a minute; back up”, I hear you ask. “Venus has a Moon?”
Of course it does. Well, kind of…
Let me explain.

It has the rather unfortunate name of 2002 VE68. That is because it was discovered on November 11, 2002 by LONEOS, the Lowell Observatory Near Earth Object Search. 2002 VE68 is an earth orbit-crossing asteroid that has been designated a Potential Hazardous Asteroid by the Minor Planet Center. For obvious reasons, this makes it a very interesting subject of study for JPL scientists.

2002 VE68 used to be a run of the mill, potential impact threat, Near Earth Object. But approximately 7000 years ago it had a close encounter with Earth that kicked it into a new orbit. It now occupies a place in orbit around the Sun where at its closest it wanders inside the orbit of Mercury and at its furthest it reaches just outside the orbit of the Earth. It is now in a 1:1 orbital resonance with Venus.

An orbital resonance is when two orbiting bodies exert a regular, periodic gravitational influence on each other due to their orbital periods being related by a ratio of two small numbers. For example, Pluto and Neptune are in an orbital resonance of 2:3, which simply means for every two times Pluto goes around the Sun, Neptune makes three trips around.

In the case of Venus and 2002 VE68, they both take the same time to orbit the Sun once. They are in a 1:1 orbital resonance. So by definition, 2002 VE68 is considered a quasi-satellite of Venus. If you watch the Orbital Viewer applet at the JPL small body page you can watch this celestial dance as the two bodies orbit the Sun and each other as 2002 VE68 dodges Earth and Mercury in the process.

Often these resonances result in an unstable interaction, in which the bodies exchange momentum and shift orbits until the resonance no longer exists. In this case, scientists believe 2002 VE68 will only remain a Venusian quasi-satellite for another 500 years or so.

So getting back to the story, Hicks and his team used the recent close apparition of 2002 VE68 to do photometric measurements over the course of three nights in November using the JPL Table Mountain 0.6m telescope near Wrightwood, California. From the color data they obtained they determined that 2002 VE68 is an X type asteroid. This is a group of asteroids with very similar spectra that could potentially have a variety of compositions. They are further broken down into Tholen classification types as either E, M or P types. Unfortunately Hicks’ team was not able to resolve the sub-classification with their equipment.

They were able to determine the approximate size of the asteroid to be 200 meters in diameter, based on its absolute magnitude, and they determined a spin rate of 13.5 hours. The amplitude of the fluctuation on the light curve of 2002 VE68 could imply hat it is actually a contact binary, two clumps of asteroidal material orbiting a center of mass in contact with each other.

For more information on some of the strange and curious beasts in the asteroidal zoo, visit the NASA Near Earth Object Program website.