Tag: asteroids

Today’s Comet 67P image

9:05 am

Comet 67P on August 2

The image above was taken on August 2 using Rosetta’s navigation camera. It has been processed by the science team to bring out the details. I have also rotated it to match the August 1 image taken at a distance of 620 miles that was taken by Rosetta’s OSIRIS narrow angle camera, designed to do the actual science.

You can see that the navigation camera does a pretty good job on its own of capturing the comet’s nucleus. Both images show that the instruments are working perfectly, and thus tell us that the next few months will be quite spectacular after Rosetta goes into orbit in three days, followed in November by the landing of Philae somewhere on the comet’s surface.

If you download both images and then switch back and forth between them you can get a better feel for the geometry of the surface features.

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Comet 67P from 1000 k

11:06 pm

67P from 1000 kilometers

Above is a new image of Comet 67P as seen from about 1000 kilometers, or about 620 miles, released by the Rosetta science team today. The image was taken on August 1 and has been processed somewhat to bring out the details. The black spot near the junction between the nucleus’s two sections is not real but an artifact of the camera’s CCD.

This image is the first real clear and sharp look at the nucleus, and what it shows us is a surface quite different from the many other asteroids that science probes have imaged close-up in the past. From this angle there are far few craters visible then is normally seen on asteroids, and the surface has complex roughness and pitted look that I suspect the planetary geologists are right now scratching their heads about and waving their arms trying to explain. My first guess, which no one should take too seriously, is that as material vents off the comet when it gets close to the Sun it leaves behind these scars.

One more thing: If you go here you can see a number of additional image releases in the last 24 hours, all fascinating. This link explains that the features that looked like craters in earlier images were actually artifacts from the camera’s CCD.

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New Rosetta comet images

6:34 pm

New images from Rosetta have a resolution of 100 meters per pixel and are finding that the neck connecting the comet’s two sections is apparently much brighter than the rest of the nucleus.

As earlier images had already shown, 67P may consist of two parts: a smaller head connected to a larger body. The connecting region, the neck, is proving to be especially intriguing. “The only thing we know for sure at this point is that this neck region appears brighter compared to the head and body of the nucleus”, says OSIRIS Principal Investigator Holger Sierks from the Max-Planck-Institute for Solar System Research (MPS) in Germany. This collar-like appearance could be caused by differences in material or grain size or could be a topographical effect.

It looks like this comet is going to turn out to be one of the most fascinating objects any space probe has visited in a long time.

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More images from Rosetta

5:24 pm

67P

The comet that Rosetta will orbit is getting stranger and stranger, with new images suggesting that it is really two objects stuck together.

The pictures show that 67P/Churyumov-Gerasimenko appears to be not one but two objects joined together. It is what scientists call a “contact binary”. How the comet came to take this form is unknown. It is possible that 67P suffered a major fracture at some point in its past; it is also possible the two parts have totally different origins.

What is clear is that the European Space Agency (Esa) mission team now has additional and unexpected considerations as it plans how to land on the comet later this year – not least, which part of the comet should be chosen for contact?

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Rosetta snaps more comet pictures

9:23 am

rotating comet nucleus

Rosetta’s new images of Comet 67P/Churyumov-Gerasimenko show the very irregular shape and rotation of its nucleus.

These images were taken on July 4 from a distance of only 23,000 miles. The rendezvous is expected in early August, with the touchdown of Rosetta’s landing probe Philae sometime in November after they have done a reconnaissance of the nucleus to pick a landing spot.

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Hubble to search for Kuiper Belt targets for New Horizons

12:12 pm

After completing a preliminary search for potential Kuiper Belt objects which the Pluto probe New Horizons might visit, scientists have decided to use the space telescope for a deeper more complete search.

As a first step, Hubble found two KBOs drifting against the starry background. They may or may not be the ideal target for New Horizons. Nevertheless, the observation is proof of concept that Hubble can go forward with an approved deeper KBO search, covering an area of sky roughly the angular size of the full Moon. The exceedingly challenging observation amounted to finding something no bigger than Manhattan Island, and charcoal black, located 4 billion miles away.

More here.

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The astronomers who allocate time on the Hubble Space Telescope have decided to devote a large block for finding a Kuiper Belt object that the probe New Horizons might fly past.

5:52 pm

The astronomers who allocate time on the Hubble Space Telescope have decided to devote a large block for finding a Kuiper Belt object that the probe New Horizons might fly past.

This allocation is still contingent upon a test observation to see if Hubble will be able to spot enough objects to make the long observations worthwhile.

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A new analysis of Apollo lunar rocks provides strong new evidence for the theory that the Moon was formed when the Earth was hit by a Mars’ sized planet.

9:14 am

A new analysis of Apollo lunar rocks provides strong new evidence for the theory that the Moon was formed when the Earth was hit by a Mars’ sized planet.

The abstract from this just released science paper summarizes the scientific problem.

Earth formed in a series of giant impacts, and the last one made the Moon. This idea, an edifice of post-Apollo science, can explain the Moon’s globally melted silicate composition, its lack of water and iron, and its anomalously large mass and angular momentum. But the theory is seriously called to question by increasingly detailed geochemical analysis of lunar rocks. Lunar samples should be easily distinguishable from Earth, because the Moon derives mostly from the impacting planet, in standard models of the theory. But lunar rocks are the same as Earth in O, Ti, Cr, W, K, and other species, to measurement precision. Some regard this as a repudiation of the theory; others say it wants a reformation. Ideas put forward to salvage or revise it are evaluated, alongside their relationships to past models and their implications for planet formation and Earth.

The new analysis has found that lunar rocks do differ from Earth in certain ways. Not surprisingly, however, the results have uncertainties.

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The predicted new meteor shower last night was less than hoped but intriguing nonetheless.

9:18 am

The predicted new meteor shower last night was less than hoped but intriguing nonetheless.

Based on a few reports via e-mail and my own vigil of two and a half hours centered on the predicted maximum of 2 a.m. CDT (7 UT) Saturday morning the Camelopardalid meteor shower did not bring down the house. BUT it did produce some unusually slow meteors and (from my site) one exceptional fireball with a train that lasted more than 20 minutes.

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According to a new study, Chelyabinsk-scale meteorite impacts happen more often than we have been aware.

9:36 am

According to a new study, Chelyabinsk-scale meteorite impacts happen more often than we have been aware.

The bright flare of the Russian meteor was hard to miss, and left 1,200 people injured in February 2013. What the human eye missed was two separate high-altitude explosions that occurred over Argentina and the North Atlantic Ocean just months later. That’s according to data from an infrasound network used to track nuke tests, released Tuesday by the B612 Foundation.

The data shows that there were 26 comparable events since 2000.

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Red tape appears to be preventing the U.S. military from releasing meteorite data obtained by its nuclear test monitoring system.

7:12 am

Red tape appears to be preventing the U.S. military from releasing meteorite data obtained by its nuclear test monitoring system.

Details of atmospheric meteor explosions, as recorded by U.S. military spacecraft sensors, were posted on a publicly accessible NASA website run by the Jet Propulsion Laboratory (JPL) in Pasadena, Calif. In fact, the military-civil cooperation was spurred by the details of the February 2013 fireball explosion over Chelyabinsk, Russia — termed a “superbolide” event. The website postings are designed to assist the scientific community’s investigation of bolides, or exceptionally bright fireballs.

However, multiple scientists noted that the JPL website had not been updated recently. That presumably meant that there was some sort of delay, as some fairly big events were detected by infrasound in the last year. “Because of budget and personnel reductions on our military partner, they ran into workforce issues to accomplish this task,” said Lindley Johnson, NEO program executive within the Planetary Science Division of NASA’s Science Mission Directorate in Washington, D.C.

In other words, it looks like everyone in the military is saying “Ain’t my job, man!” so it doesn’t get done. They need to assign someone the job and be done with it.

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Geologists, using computer models, have reconstructed the size and impact velocity of a giant asteroid that hit the Earth approximately 3.26 billion years ago.

11:51 am

Geologists, using computer models, have reconstructed the size and impact velocity of a giant asteroid that hit the Earth approximately 3.26 billion years ago.

This is a fascinating result, but it is very important to recognize its very large uncertainties. The article for example says almost nothing about how these conclusions were reached, except for this one paragraph:

Lowe, who discovered telltale rock formations in the Barberton greenstone a decade ago, thought their structure smacked of an asteroid impact. The new research models for the first time how big the asteroid was and the effect it had on the planet, including the possible initiation of a more modern plate tectonic system that is seen in the region, according to Lowe. [emphasis mine]

I have highlighted that one word because it reveals a great deal. What they did was to create a computer model of the data they had, which was merely very unusual geology spread over a certain region called the Barberton Greenstone Belt. Note also that this region is not where the impact occurred. “The study’s co-authors think the asteroid hit the Earth thousands of kilometers away from the Barberton Greenstone Belt, although they can’t pinpoint the exact location.”

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A skydiver’s helmet cam captures a meteorite zipping past him as it falls.

2:11 pm

A skydiver’s helmet cam videotapes a meteorite zipping past him as it falls.

The incident happened back in the summer of 2012, when skydiver Anders Helstrup and other members of the Oslo Parachute Club took to the skies above Hedmark, Norway. Helstrup documented the jump with two cameras fixed to the front and back of his helmet. Helstrup tells NRK (the largest media outlet in Norway) that on the way down he felt “something” happen, but didn’t know what. It was only after landing and reviewing his camera footage that he discovered something shocking: a rock had fallen from the heavens and missed him by just a few yards.

Video below the fold. The news woman is annoying, but the footage is quite cool.
» Read more

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Astronomers have found an asteroid with its own rings.

10:07 pm

Astronomers have found an asteroid with its own rings.

Chariklo is the largest member of a class known as the Centaurs and it orbits between Saturn and Uranus in the outer Solar System. Predictions had shown that it would pass in front of the star UCAC4 248-108672 on 3 June 2013, as seen from South America. Astronomers using telescopes at seven different locations, including the 1.54-metre Danish and TRAPPIST telescopes at ESO’s La Silla Observatory in Chile, were able to watch the star apparently vanish for a few seconds as its light was blocked by Chariklo — an occultation.

But they found much more than they were expecting. A few seconds before, and again a few seconds after the main occultation there were two further very short dips in the star’s apparent brightness. Something around Chariklo was blocking the light! By comparing what was seen from different sites the team could reconstruct not only the shape and size of the object itself but also the shape, width, orientation and other properties of the newly discovered rings.

The team found that the ring system consists of two sharply confined rings only seven and three kilometres wide, separated by a clear gap of nine kilometres — around a small 250-kilometre diameter object orbiting beyond Saturn.

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An asteroid will eclipse the bright naked eye star Regulus for 14 seconds on March 19-20, and everyone in the New York City metropolitan area will be able to watch.

10:58 am

An asteroid will eclipse the bright naked eye star Regulus for 14 seconds on March 19-20, and everyone in the New York City metropolitan area will be able to watch.

Late on the night of March 19–20, the faint asteroid Erigone (eh-RIG-uh-nee) will briefly eclipse the bright naked-eye star Regulus for more than 20 million people in the New York metropolitan area and parts of Long Island, New Jersey, Connecticut, upstate New York, and Ontario. The star will vanish from sight for up to 14 seconds around 2:06 a.m. EDT on the morning of the 20th for New Yorkers, and a minute or two later farther north.

If the sky is clear, Regulus will be a cinch for anyone to spot — no astronomy experience required! Around 2 a.m. or a bit before, go out and face the Moon. Extend your arms straight out to your sides. Regulus will be straight above your right hand, roughly as high as the Moon is. It’s the brightest star in that area.

Scientists are also asking ordinary citizens to help gather data, which if sufficient will allow them to recreate a reasonably accurate silhouette of the asteroid, thus determining its size and shape.

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Another rock will fly past the Earth today, killing no one.

4:07 pm

Chicken Little report: Another rock will fly past the Earth today, killing no one.

The 33-foot-wide (10 meters) near-Earth asteroid 2014 EC will come within 34,550 miles (55,600 kilometers) of Earth’s surface this evening (March 6) — just 14 percent of the distance between our planet and the moon, which is about 239,000 miles (385,000 km) on average.

The key quote, however, is this:

Such back-to-back flybys are pretty special, though they can’t exactly be called rare events, [JPL scientist Don] Yeomans said. “For small asteroids, one would expect a flyby of the Earth, to within the moon’s distance, about every two weeks,” he said.

In other words, these flybys happen a lot, with no consequences.

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Hubble photographs the break-up of an asteroid.

8:36 am

Hubble photographs the break-up of an asteroid.

The ongoing discovery of more fragments makes it unlikely that the asteroid is disintegrating due to a collision with another asteroid, which would be instantaneous and violent in comparison to what has been observed. Some of the debris from such a high-velocity smash-up would also be expected to travel much faster than has been observed.

It is also unlikely that the asteroid is breaking apart due to the pressure of interior ices warming and vaporising. The object is too cold for ices to significantly sublimate, and it has presumably maintained its nearly 480-million-kilometre distance from the Sun for much of the age of the Solar System.

This leaves a scenario in which the asteroid is disintegrating due to a subtle effect of sunlight that causes the rotation rate to slowly increase over time. Eventually, its component pieces gently pull apart due to centrifugal force. The possibility of disruption by this phenomenon — known as the YORP effect — has been discussed by scientists for several years but, so far, never reliably observed.

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A 100-foot diameter newly discovered asteroid will zip past the Earth inside the Moon’s orbit today at 4:07 pm Eastern.

9:35 am

Chicken Little report: A 100-foot diameter newly discovered asteroid will zip past the Earth inside the Moon’s orbit today at 4:07 pm Eastern.

The asteroid, dubbed 2014 DX 110, is about 100 feet in diameter and is set to come within 216,000 miles of Earth — a close shave by astronomical standards, considering our Moon orbits the Earth at a distance of about 238,900 miles.

While an object that size may not seem imposing, if it were to strike the Earth, it would release a devastating amount of energy greater than a nuclear weapon. The infamous asteroid that exploded over Tunguska, Siberia, on June 30, 1908, has been estimated to be about 30 meters to 60 meters — 100 feet to 200 feet — in diameter.

While it is true that the impact would be significant, this news report does the typical fear-mongering to make the story seem interesting. The problem, however, is that the detection of these fly-bys is becoming more frequent. The number of asteroids isn’t changing, but our ability to spot them is, and with more frequent discoveries comes more frequent news stories like this. I fear that such stories — fueled by press releases from various astronomy organizations — are going to begin to sound like a kid “crying wolf” to the general public. The threat from an asteroid impact is real, even if most asteroids miss us. Desensitizing the public to the threat is not a good thing.

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A September asteroid impact on the Moon captured by Spanish astronomers.

8:56 am

A September asteroid impact on the Moon captured as it happened by Spanish astronomers.

On 11 September 2013, Prof Jose M. Madiedo was operating two telescopes in the south of Spain that were searching for these impact events. At 2007 GMT he witnessed an unusually long and bright flash in Mare Nubium, an ancient lava-filled basin with a darker appearance than its surroundings. The flash was the result of a rock crashing into the lunar surface and was briefly almost as bright as the familiar Pole Star, meaning that anyone on Earth who was lucky enough to be looking at the Moon at that moment would have been able to see it. In the video recording made by Prof Madiedo, an afterglow remained visible for a further eight seconds. The September event is the longest and brightest confirmed impact flash ever observed on the Moon.

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Three relatively large near Earth asteroids have just been discovered.

10:13 pm

Chicken Little report: In October of last year three relatively large near Earth asteroids were discovered unexpectedly.

Read the report, which is the second notice at the link. I missed it at the time. Each of these new discoveries was interesting and surprising. Key quote: “The delayed discovery of 2013 US10 is a bit harder to explain, since current population models suggest that almost all near-Earth asteroids of this size and orbit should have already been found.” Apparently not.

In related news, a several hundred foot wide asteroid zipped past the Earth this evening.

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Mars Reconnaissance Orbiter spots a new crater on Mars.

12:38 pm

Mars Reconnaissance Orbiter spots a new crater on Mars.

The scar appeared at some time between imaging of this location by the orbiter’s Context Camera in July 2010 and again in May 2012. Based on apparent changes between those before-and-after images at lower resolution, researchers used HiRISE to acquire this new image on Nov. 19, 2013. The impact that excavated this crater threw some material as far as 9.3 miles (15 kilometers).

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An analysis of the rotation of the peanut-shaped asteroid 25143 Itokawa suggests that its smaller end is actually far denser than its bigger end.

9:03 am

An analysis of the rotation of the peanut-shaped asteroid 25143 Itokawa suggests that its smaller end is actually far denser than its bigger end.

Previously, some researchers have proposed that Itokawa is actually two asteroids in contact with one another, a scenario strongly supported by the new results, the team contends. It’s not clear whether the odd configuration results from the merger of a two-asteroid system or merely clumps of material that fell back together after a larger asteroid was blasted apart by an immense collision.

The researchers also found that the asteroid’s rotation is actually increasing by 45 milliseconds per year.

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Astronomers have detected water vapor spurting from Ceres, the solar system’s largest asteroid.

9:41 am

Using the Herschel Space Telescope astronomers have detected water vapor spurting from Ceres, the solar system’s largest asteroid.

Herschel’s sensors spied plumes during three of the four observation periods. The strength of absorption varied over a matter of hours, a trend probably caused by relatively small sources of water vapour rotating in and out of view of Earth, the researchers say.

Data gathered in March 2013 suggest that the plumes originated from two widely separated, 60-kilometre-wide spots in the dwarf planet’s mid-latitude regions. Together, these spots ejected about 6 kilograms of water vapour into space each second. Neither ground-based observations nor images from the Hubble Space Telescope are keen enough to identify the as-yet-mysterious areas, says Küppers. “We don’t know what these features are, we just know that they’re darker than their surroundings,” he notes.

The NASA probe Dawn will arrive at Ceres early next year, and take a good look at these plumes. Should be exciting.

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The recently reactivated WISE space telescope has discovered its first new asteroid.

3:31 pm

The recently reactivated WISE space telescope has discovered its first new asteroid.

2013 YP139 is about 27 million miles (43 million kilometers) from Earth. Based on its infrared brightness, scientists estimate it to be roughly 0.4 miles (650 meters) in diameter and extremely dark, like a piece of coal. The asteroid circles the sun in an elliptical orbit tilted to the plane of our solar system and is classified as potentially hazardous. It is possible for its orbit to bring it as close as 300,000 miles from Earth, a little more than the distance to the moon. However, it will not come that close within the next century.

WISE, renamed NEOWISE by NASA, is expected to come up with a lot more of these in the coming years.

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