How Many Asteroids Are Out There?

Answer: a LOT. And there’s new ones being discovered all the time, as this fascinating animation by Scott Manley shows.


Created using data from the IAU’s Minor Planet Center and Lowell Observatory, Scott’s animation shows the progression of new asteroid discoveries since 1980. The years are noted in the lower left corner.

As the inner planets circle the Sun, asteroids light up as they’re identified like clusters of fireflies on a late summer evening. The clusters are mainly positioned along the outer edge of Earth’s orbit, as this is the field of view of most of our telescopes.

Once NASA’s WISE spacecraft begins its search around 2010 the field of view expands dramatically, as well as does the rate of new discoveries. This is because WISE’s infrared capabilities allowed it to spot asteroids that are composed of very dark material and thus reflect little sunlight, yet still emit a telltale heat signature.

While Scott’s animation gives an impressive — and somewhat disquieting — illustration of how many asteroids there are knocking about the inner Solar System, he does remind us that the scale here has been very much compacted; a single pixel at the highest resolution corresponds to over 500,000 square kilometers! So yes, over half a million asteroids is a lot, but there’s also a lot of space out there (and this is just a 2D top-down view too… it doesn’t portray any vertical depth.)

While most asteroids are aligned with the horizontal plane of the Solar System, there are a good amount whose orbits take them at higher inclinations. And on a few occasions they even cross Earth’s orbit.

(Actually, on more than just a few.)

Read: 4700 Asteroids Want to Kill You

An edge-on view of the Solar System shows the positions of asteroids identified by the NEOWISE survey. About 4700 potentially-hazardous asteroids (PHAs) have been estimated larger than 100 meters in size. (NASA/JPL-Caltech)

As far as how many asteroids there are… well, if you only consider those larger than 100 meters orbiting within the inner Solar System, there’s over 150 million. Count smaller ones and you get even more.

I don’t know about you but even with the distances involved it’s starting to feel a little… crowded.

You can see more of Scott Manley’s videos on YouTube here (including some interesting concepts on FTL travel) and learn more about asteroids and various missions to study them here.

Inset image: the 56-km (35-mile) wide asteroid Ida and its satellite, seen by the Galileo spacecraft in 1993. (NASA)

Curiosity Captures a Martian Eclipse

Yes, Mars gets eclipses too! This brief animation, made from ten raw subframe images acquired with Curiosity’s Mastcam on September 13 — the 37th Sol of the mission — show the silhouette of Mars’ moon Phobos as it slipped in front of the Sun’s limb.

The entire animation spans a real time of about 2 minutes.

As a moon Phobos really is an oddity. In addition to its small size – only 8 miles (13 km) across at its widest – and irregular shape, it also orbits its parent planet at a very low altitude, only 5,840 miles (9,400 km) and thus needs to travel at a relatively high velocity in order to even stay in orbit. Phobos actually orbits Mars over three times faster than Mars rotates, appearing to rise in Mars’ western sky. And its orbit is so low that it can’t even be seen from the polar regions!

Since Phobos, and its even more petite sibling Deimos, are so small, the Mars rovers won’t ever see a total solar eclipse. In fact these events are often referred to as transits rather than actual eclipses.

This isn’t the first time an eclipse was captured by a Mars Exploration Rover; Opportunity witnessed a similar partial eclipse of the Sun by Phobos in December 2010, and Spirit caught a lunar (or “Phobal?”) eclipse on camera back in 2005, when the moon passed into the shadow of Mars.

Curiosity’s find was no accident, either, as mission engineers had the Mastcam already positioned to capture the event. Preparation really pays off!

See the latest images and news from the MSL mission here.

Images: NASA/JPL-Caltech/Malin Space Science Systems. Animation by Jason Major. Inset image: Phobos as seen by Mars Express ESA/DLR/FU Berlin (G. Neukum)

UPDATE 9/19/12: See a close-up animation of the eclipse event here.

What If All of Kepler’s Exoplanets Orbited the Same Star?


That’s exactly the scenario shown by a mesmerizing animation called “Worlds” by Alex Parker — a single system containing 2299 multiple-transit planetary candidates identified to date by NASA’s Kepler space telescope, which is currently scrutinizing a field of view within the constellation Cygnus to detect the oh-so-faint reductions in brightness caused by planets passing in front of their stars.

The search requires patience and precision; it’s not really this crowded out there.

Alex’s animation takes 2299 candidates that have been observed multiple times, each shown to scale in relation to their home star, and puts them in orbit around one star, at their relative distances.

The result, although extravagantly impossible, is no less fascinating to watch. (I suggest going full screen.)

“The Kepler observatory has detected a multitude of planet candidates orbiting distant stars,” Alex writes on his Vimeo page. “The current list contains 2321 planet candidates, though some of these have already been flagged as likely false-positives or contamination from binary stars. This animation does not contain circumbinary planets or planet candidates where only a single transit has been observed, which is why ‘only’ 2299 are shown.

“A fraction of these candidates will likely be ruled out as false positives as time goes on, while the remainder stand to be confirmed as real planets by follow-up analysis,” Alex adds.

The white ellipses seen when the animation pulls back are the relative sizes of the orbits of Mercury, Venus and Earth.

At this time the Kepler mission has identified 2321 planetary candidates, with 74 exoplanets confirmed. See more on the Kepler mission here.

Animation: Alex Parker. Image: Kepler mission planet candidates family portrait (NASA Ames/Jason Rowe/Wendy Stenzel)

CGI Movie From 1963 Shows Satellite Orbit

In what may very well be the world’s first computer-generated animation, this video shows the motion of a box-like “satellite” orbiting a rotating sphere… Pixar, eat your heart out.

Created in 1963 by Edward E. Zajac, a programmer at Bell Labs from 1954 to 1983, the animation was made to demonstrate a theoretical satellite that used gyroscopes to maintain an Earth-facing orientation. Only a year after the launch of Telstar 1, the world’s first communications satellite (which just had its 50th anniversary) Bell Labs was very much invested in the development of satellite technology.

According to the description on the ATT Tech YouTube channel:

Zajac programmed the calculations in FORTRAN, then used a program written by Zajac’s colleague, Frank Sinden, called ORBIT. The original computations were fed into the computer via punch cards, then the output was printed onto microfilm using the General Dynamics Electronics Stromberg-Carlson 4020 microfilm recorder. All computer processing was done on an IBM 7090 or 7094 series computer.

I’d like to say that many Bothans died to bring us this information but… well, I guess I just did.

Footage courtesy of AT&T Archives and History Center in Warren, NJ. H/T to Paul Caridad at VisualNews.com.

A Shimmering, Simmering Sunspot

This quick animation made by astrophotographer Alan Friedman shows a 30-minute view of sunspot 1520, a large region of magnetic activity on the Sun that’s currently aimed directly at Earth. Although 1520 has been quiet for the past couple of days, it’s loaded with a delta-class magnetic field — just right for launching powerful X-class flares our way. There’s no guarantee that it will, but then there’s no guarantee that it won’t either.

(Click the image to play the animation.)

Alan captured the images from his location in upstate New York using a 10″ Astro-Physics scope and PGR Grasshopper CCD. A master at solar photography — several of his hydrogen alpha images have been featured here on Universe Today as well as other popular astronomy news sites — Alan’s work never fails to impress.

A static, color version of sunspot 1520 can be seen here… what Alan calls “a magnetic beauty.”

Although the sunspots don’t change much over the course of the animation, the surrounding texture on the Sun’s photosphere can be seen to shift and move rapidly. These bright kernels are called granules, and are created by convective currents on the Sun. An individual granule typically lasts anywhere from 8 to 20 minutes and can be over 600 miles (1000 km) across.

The overall wavering effect is caused by distortion from Earth’s atmosphere.

While 1520 is facing Earth we’re subject to any flares or CMEs that may erupt from it, potentially sending a solar storm our way. In another week or so it will have rotated safely around the Sun’s limb and eventually dissipate altogether… but then, it is solar maximum and so there’s likely to be more active regions just like it (or even larger!) coming around the bend.

When they do come, there’s a good chance that Alan will grab some pics of those too.

Check out more of Alan’s photography on his site AvertedImagination.com.

Image © Alan Friedman. All rights reserved.

 

What’s a Higgs Boson, Anyway?

With the science world all abuzz in anticipation of tomorrow’s official announcement from CERN in regards to its hunt for the Higgs, some of you may be wondering, “what’s a Higgs?” And for that matter, what’s a boson?

The video above, released a couple of months ago by the talented Jorge Cham at PHDcomics, gives a entertaining run-down of subatomic particles, how they interact and how, if it exists — which, by now, many are sure it does — the Higgs relates to them.

It’s the 7-minutes course in particle physics you’ll wish you had taken in college (unless you’re a particle physicist in which case… well, you’d still probably have enjoyed it.)

Credit: PHDcomics.com

What Will Happen During Tomorrow’s SpaceX Launch:

With less than a day left before SpaceX’s historic launch of the first commercial vehicle to the ISS, slated for 4:55 am EDT on Saturday, May 19, here’s a video of what will happen once the Falcon lifts off.

(Part of me really wishes that they’ll be pumping out some dramatic music when it launches!)

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The video, created by NASA in 2011, shows the events that will take place from the initial launch at SpaceX’s Cape Canaveral facility to the release of the Dragon capsule and its eventual docking with the ISS on Tuesday, as well as its return to Earth (yes, it’s reusable!)

The Dragon capsule contains 674 lbs (305 kg) of food and supplies for the Expedition 31 crew.

In addition to what’s aboard Dragon, the Falcon rocket will also be taking the cremated remains of 308 people — including Star Trek actor James Doohan and NASA astronaut Gordon Cooper — into space, via a private company called Celestis.

Read more about tomorrow’s launch here. And to watch the event live, stay tuned to SpaceX.com.

Video: NASA

Update 5/19: As it turned out, none of the above occurred. Instead, this happened. Maybe better luck on Tuesday!

ISS Caught Between the Moon and New York City

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Now as the theme from Arthur plays in your head you can enjoy this GIF animation of the ISS passing across the face of a daytime Moon, photographed by Alan Friedman from his location in upstate New York.

I know it’s crazy, but it’s true.

Alan captured these images at 10:30 a.m. EST back on September 2, 2007, and slowed down the animation a bit; in real-time the event lasted less than half a second. (Click the image for an even larger version.)

Atmospheric distortion creates the “wobbly” appearance of the Moon.

Alan Friedman is a talented photographer, printer (and avid vintage hat collector) living in Buffalo, NY. His images of the Sun in hydrogen alpha light are second-to-none and have been featured on many astronomy websites. When he’s not taking amazing photos of objects in the sky he creates beautiful hand-silkscreened greeting cards at his company Great Arrow Graphics.

See more of Alan’s astrophotography on his website, Averted Imagination.

Image © Alan Friedman. All rights reserved.

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NOTE: Although this article previously stated that the images were taken Jan. 12, 2012, they were actually captured in September 2007 and re-posted on Jan. 13 of this year. Alan states that he’s since learned how to judge exposure so the ISS doesn’t appear as a streak, but personally he likes (as do I) how this one came out.

Let’s see… September 2007… that would have been Expedition 15!

Ride Along with Rhea

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Assembled from 29 raw images taken by the Cassini orbiter on Monday, April 25, this animation brings us along an orbital ride with Rhea as it crosses Saturn’s nighttime face, the planet’s shadow cast across the ringplane. Sister moons Dione and Tethys travel the opposite lane in the background, eventually appearing to sink into Saturn’s atmosphere.

Rhea's heavily cratered surface, imaged by Cassini on October 2010. NASA/JPL/SSI

The exposure varies slightly from frame to frame due to the fact that they are not all taken with the same color channel filter.

Rhea (1,528 kilometers, or 949 miles, wide), Dione (1,123 kilometers, or 698 miles wide) and Tethys (1,066 kilometers, or 662 miles wide) are all very similar in composition and appearance. The moons are composed mostly of water ice and rock, each covered in craters of all sizes and crisscrossed by gouges, scarps and chasms. All three are tidally locked with Saturn, showing the same face to their parent planet in the same way that the Moon does with Earth.

The Cassini spacecraft was 2,227,878 km (1,384,339 miles) from Rhea when the images were taken.

(The original images have not been validated or calibrated. Validated/calibrated images will be archived with the NASA Planetary Data System in 2012.)

Image credit: NASA / JPL / Space Science Institute. Animation by Jason Major.