Asteroids Archives

July 10, 2014December 23, 2015 by Bob King

Flaming Space Junk Makes Jaws Drop in Australia

Frame grab from a Youtube video of the brilliant meteor that flared over Australia overnight.

“It first looked like a plane with fire coming out of the tail.” — Aaron O.

“I have never seen anything like it. Big, bright and moving gently across sky – slower than a plane, not falling at all but moving across.” — Shannon H.

“Viewed from cockpit of aircraft at 37,000′. Was visible for two or three minutes.” — Landy T.

Flaming plane? Incandescent visitor from the asteroid belt? As the these comments from the AMS Fireball Log attest, the brilliant and s-l-o-w fireball that seared the sky over southeastern Australia tonight was probably one of the most spectacular displays of re-entering space junk witnessed in recent years.

Ted Molczan, citizen satellite tracker and frequent contributor to the amateur satellite watchers SeeSat-L site, notes that the timing and appearance almost certainly point to the decay or de-orbiting of the Russian Soyuz 2-1B rocket booster that launched the meteorological satellite Meteor M2 on July 8.

Meteor over New South Wales. Look closely near the end and you’ll see it disintegrate into small pieces.

The magnificent man-made meteor, weighing some 4,400 pounds (2,000 kg), was seen from Melbourne to Sydney across the states of Victoria and New South Wales around 10 p.m. Hundreds of people were stopped in their tracks. Most noticed how slowly the fireball traveled and how long it continue to burn on the way down.

Spacecraft that reenter from either orbital decay or controlled entry usually break up at altitudes between 45-52 miles (84-72 km) traveling around 17,500 mph (28,000 km/hour) . Compression and friction from the ever-thickening air cause the craft, or in this case, the rocket booster, to slow down and heat up to flaming incandescence just like a hunk of space rock arriving from the asteroid belt. In both cases, we see a brilliant meteor, however manmade debris.

Jan 21, 2001, a Delta 2 third stage, known as a PAM-D, reentered the atmosphere over the Middle East. The titanium motor casing, weighing about 70 kg, landed in Saudi Arabia about 240 km from the capital of Riyadh. Credit: NASA, Orbital Debris Program Office — A Delta 2 third stage, known as a PAM-D, reentered the atmosphere over the Middle East on Jan. 21, 2001. The titanium motor casing, weighing about 154 lbs. (70 kg), landed in Saudi Arabia about 150 miles from the capital of Riyadh. Credit: NASA, Orbital Debris Program Office

Occasional meteoroids break apart in the atmosphere and scatter meteorites just as pieces of occasional satellites, especially large, heavy craft, can survive the plunge and land intact – if a tad toasted. Whether anything remains of Russian rocket stage or where exactly it fell is still unknown. Here are a few more photos of successful space junk arrivals.

The only person to be hit by manmade space debris was Lottie Williams in 1997. She was unharmed. Credit: Tulsa World

Reportedly, only one person has been struck by satellite debris. In 1997 Lottie Williams of Tulsa, Oklahoma was hit on the shoulder while walking by a small, twisted piece of metal weighing as much as a crushed soda can. It was traced back to the tank of a Delta II rocket that launched a satellite in 1996. I suppose it’s only a matter of time before someone else gets hit, but the odds aren’t great. More likely, you’ll see what alarmed and delighted so many southeastern Australians Thursday night: a grand show of disintegration.

July 2, 2014December 23, 2015 by Elizabeth Howell

Ancient Asteroid Impacts Left Serpentine Traces On Vesta: Study

The asteroid Vesta as seen by the Dawn spacecraft. Credit: NASA/JPL-Caltech/UCAL/MPS/DLR/IDA

While “dark materials” may leave some of us thinking about a certain Philip Pullman book series, on the asteroid Vesta its presence belies something equally exotic: old smaller asteroid impacts on its surface.

The dark stuff on the lighter surface has puzzled researchers since it was discovered in 2011 (and has been brought up in other studies), but a new team says it has found that serpentine is among the components. Because that mineral can’t survive temperatures that are more than 400 degrees Celsius (752 degrees Fahrenheit), this means that scenarios such as volcanic eruptions can’t have caused it. This leaves only smaller asteroids, the team says.

“These meteorites are regarded as fragments of carbon-rich asteroids. The impacts must have been comparatively slow, because an asteroid crashing at high speeds would have produced temperatures too high to sustain serpentine,” the Max Planck Institute for Solar System Research stated.

Image of the crater Numisia on Vesta, where researchers found the spectral signature of serpentine. Picture taken by NASA's Dawn spacecraft. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA — Image of the crater Numisia on Vesta, where researchers found the spectral signature of serpentine. Picture taken by NASA’s Dawn spacecraft. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

“In a previous study, scientists from the MPS had calculated how dark material would be distributed on Vesta as a result of a low-speed oblique impact. Their results are consistent with the distribution of dark material on the edge of one of the two large impact basins in the southern hemisphere.”

The results came from analyzing images the NASA Dawn spacecraft took of Vesta between July 2011 and September 2012. The researchers recalibrated the data and also backed up their results by examining serpentine in laboratory conditions.

The research was published in the journal Icarus and you can also read a summary of the research here, from a presentation at the 2014 Lunar and Planetary Science Conference.

Source: Max Planck Institute for Solar System Research

July 1, 2014December 23, 2015 by Bob King

Eureka! Kola Fireball Meteorites Found in Russia

Amateur astronomer and physics teacher Asko Aikkila managed to catch the Kola fireball on videotape in Kuusamo, Finland on April 19, 2014. The picture has been processed to enhance the details. Credit: Asko Aikkila / Finnish Fireball Network

A spectacular fireball that crackled across the sky near the Russia-Finnish border on April 19th this year left more than a bright flash. A team of meteor researchers from Finland, Russia and the Czech Republic scoured the predicted impact zone and recently discovered extraterrestrial booty.

A 120 gram fragment of the Annama meteorite. Streamlines of molten material heated during atmospheric entry can be seen on the crust. Credit: Jakub Haloda — A 120 gram fragment (left) of the Annama meteorite found on May 29, 2014. Streamlines of molten material heated during atmospheric entry can be seen on the crust. At right, a 48g fragment found on the following day. Credit: Jakub Haloda (left) and Grigory Yakovlev

There’s a lot of excitement about the fall because it’s the first time a meteorite was found based on coordinated all-sky camera network observations by the Ursa Finnish Fireball Network. Esko Lyytinen of the network with help from Jarmo Moilanen and Steinar Midtskogen reconstructed the meteoroid’s trajectory and dark flight (when it’s no longer luminous but yet to strike the ground) using simulations based on photos, videos and eyewitness reports.

Kola fireball meteors ended up near the Russian-Norwegian border. The fireball trajectory Esko Lyytinen of Ursa modeling of Heaven, watch videos on the findings and Murmansk. — Kola fireball meteors fell near the Russian-Norwegian border. The
fireball trajectory was modeled byEsko Lyytinen of the Ursa Finnish Fireball Network. Credit: Kuva Mikko Suominen / Celestia with info boxes translated by the author

The initial mass of meteoroid is estimated at about 1,100 pounds (500 kg). Much of that broke apart in the atmosphere and fell harmlessly as smaller stones. An international team of scientists mounted a 5-day expedition in late May after snow melt and before green up to uncover potential space rocks in the strewnfield, the name given to the oval-shaped zone where surviving fragments pepper the ground.

Russian amateur astronomer Nikolai Kruglikov discovered the first fragment of Annama meteorite on May 29, 2014 in the middle of a dirt road. Credit: Tomas Kohout — Russian amateur astronomer Nikolai Kruglikov discovered the first meteorite fragment in the middle of a dirt road. Credit: Tomas Kohout

On May 29, 2014, first 120 gram (4.2 ounce) meteorite fragment was found by Nikolai Kruglikov of Russia’s Ural Federal University on a forest road within the predicted impact area. The crew had been searching 1o hours a day when Kruglikov stopped the car to check out a suspect rock:

“Suddenly he started dancing and yelling. At first I could hardly believe it was a true discovery, but then I checked the composition of the rock using my instrument”, said Tomas Kohout, University of Helsinki physicist who participated in the hunt. The fusion-crusted stone displayed classic flow features from melting rock during high-speed atmospheric entry.

The very next day a second 48 gram crusted meteorite popped up. More are undoubtedly out there but the heavy brush numerous lakes make the finding challenging.

The crew is calling the new arrival the ‘Annama meteorite’ as it fell near the Annama River in Russia about 62 miles west of Murmansk. The Czech Geological Survey examined the space rocks and determined them to be ordinary chondrites representing the outer crust of an asteroid that got busted to bits in a long-ago collision. More than 95% of stony meteorites fall into this category including the 2013 fireball of Chelyabinsk, Russia.

Dashcam video of the brilliant fireball that dropped the ‘Annama meteorites’

“The Kola fireball is a rarity – it is one of only 22 cases where it was possible to determine its pre-impact solar system orbit before the impact with Earth’s atmosphere,” says Maria Gritsevich of the Finnish Geodetic Institute. “Knowing where the meteorite originates will help us better understand the formation and evolution of the solar system.” Congratulations Ursa!

June 26, 2014December 23, 2015 by Bob King

Ceres and Vesta Converge in the Sky on July 5: How to See It

Ceres and Vesta are converging in Virgo not far from Mars and Spica. On July 5, the duo will be just 10' apart and visible in the high power telescope field of view. Positions are shown every 5 days for 10 p.m. EDT and stars to magnitude +8.5. Created with Chris Marriott's SkyMap software

I bet you’ve forgotten. I almost did. In April, we reported that Ceres and Vesta, the largest and brightest asteroids respectively, were speeding through Virgo in tandem. Since then both have faded, but the best is yet to come. Converging closer by the day, on July 5, the two will make rare close pass of each other when they’ll be separated by just 10 minutes of arc or the thickness of a fat crescent moon.

Vesta (left) and Ceres. Vesta was photographed up close by the Dawn spacecraft from July 2011-Sept. 2012, while the best views we have to date of Ceres come from the Hubble Space Telescope. The bright white spot is still a mystery. Credit: NASA — Vesta (left) and Ceres. Vesta was photographed up close by the Dawn spacecraft from July 2011-Sept. 2012, while the best views we have to date of Ceres come from the Hubble Space Telescope. The bright white spot is still a mystery. NASA will plunk Dawn into orbit around Ceres next February. Credit: NASA

Both asteroids are still within range of ordinary 35mm and larger binoculars; Vesta is easy at magnitude +7 while Ceres still manages a respectable +8.3. From an outer suburban or rural site, you can watch them draw together in the coming two weeks as if on a collision course. They won’t crash anytime soon. We merely see the two bodies along the same line of sight. Vesta’s closer to Earth at 164 million miles (264 million km) and moves more quickly across the sky compared to Ceres, which orbits 51 million miles (82 million km) farther out.

Ceres and Vesta are happily near an easy naked eye star, Zeta Virginis, which forms an isosceles triangle right now with Mars and Spica. The map shows the sky around 10 p.m. local time facing southwest. Stellarium — Ceres and Vesta lie near an easy naked eye star, Zeta Virginis, which forms an isosceles triangle right now with Mars and Spica. The map shows the sky around 10 p.m. local time tonight facing southwest. Stellarium

Right now the two asteroids are little more than a moon diameter apart not far from the 3rd magnitude star Zeta Virginis. Happily, nearby Mars and Spica make excellent guides for finding Zeta. Once you’re there, use binoculars and the more detailed map to track down Ceres and Vesta.

Virgo will be busy Saturday night July 5, 2014 when the waxing moon is in close conjunction with Mars with Ceres and Vesta at their closest. Stellarium — Virgo will be busy Saturday night July 5, 2014 when the waxing moon passes about 1/2 degree from Mars as Ceres and Vesta squeeze closest. Stellarium

In early July they’ll look like a wide double star in binoculars and easily fit in the same high power telescopic view. Vesta has always looked pale yellow to my eye. Will its color differ from Ceres? Sitting side by side it will be easier than ever to compare them. Vesta is a stony asteroid with a surface composed of solidified (and meteoroid-battered) lavas; Ceres is darker and covered with a mix of water ice and carbonaceous materials.

On the night of closest approach, it may be difficult to spot dimmer Ceres in binoculars. By coincidence, the 8-day-old moon will be very close to the planet Mars and brighten up the neighborhood. We’ll report more on that event in a future article.

With so much happening the evening of July 5, let’s hope for a good round of clear skies.

June 19, 2014December 23, 2015 by Elizabeth Howell

See This Orange Smudge? This Could Be NASA’s Target For The Asteroid Mission

An image of asteroid 2011 MD -- a candidate for a potential future mission to an asteroid -- taken by NASA's Spitzer Space Telescope in February 2014. The exposure took 20 hours to accomplish and was done in infrared light. Credit: NASA

In the center of the image above is an orange smudge. It may not look like much to the untrained eye, but to NASA it represents potential. It’s a candidate asteroid target for a mission the agency badly wants to happen, even though nobody knows for sure yet if things will line up for humans to visit there one day.

This is a picture of asteroid 2011 MD taken by NASA’s Spitzer Space Telescope. It’s about 6 meters (20 feet) across and appears to have a low density, the agency said in a statement. While NASA is still looking for other candidates for its asteroid initiative, the agency added this would be the sort of asteroid it’s looking to visit.

“The asteroid appears to have a structure perhaps resembling a pile of rocks, or a ‘rubble pile.’Since solid rock is about three times as dense as water, this suggests about two-thirds of the asteroid must be empty space,” NASA stated in this press release.

“The research team behind the observation says the asteroid could be a collection of small rocks, held loosely together by gravity, or it may be one solid rock with a surrounding halo of small particles.”

Artist's conception of the structure around 2011 MD, a candidate asteroid for NASA's proposed asteroid redirect mission. Credit: NASA/JPL-Caltech — Artist’s conception of the structure around 2011 MD, a candidate asteroid for NASA’s proposed asteroid redirect mission. Credit: NASA/JPL-Caltech

You can read more about this asteroid in Astrophysical Journal Letters. There was another study done on 2011 MD earlier this year that was also in ApJL, or in preprint version in Arxiv.

Announcing this asteroid candidate was just one of several things NASA made public today. It added that it plans to send off an ARM (Asteroid Redirect Mission) robotic spacecraft in 2019, and about one year before that it will decide which asteroid to send this spacecraft to.

NASA has two concept ideas for ARM, and it’s planning to award $4.9 million (it had initially planned for up to $6 million) for others to make more detailed investigations into which is the more feasible. Read the full list of recipients at this NASA website.

One idea is to pick up a small asteroid, and the other is to carve off a small portion of a bigger asteroid. Whatever the choice, it would involve coming up with an object that is less than 32 feet (10 meters) across to move to the moon’s orbit. NASA will decide what to do later this year.

“The studies will be completed over a six-month period beginning in July, during which time system concepts and key technologies needed for ARM will be refined and matured. The studies also will include an assessment of the feasibility of potential commercial partners to support the robotic mission,” NASA stated.

An astronaut retrieves a sample from an asteroid in this artist's conception. Credit: NASA — An astronaut retrieves a sample from an asteroid in this artist’s conception. Credit: NASA

Also, some more details about other candidates: NASA has found nine so far that it deems suitable, and size estimates have been made on three of those nine candidates. A fourth, 2008 HU4, will be close to Earth in 2016 and allow for “interplanetary radar” to learn more about its size and rotation, NASA said. The other ones will not get close enough to Earth for a better look before the mission selection is done.

NASA added that it expects to add more through its Near-Earth Object program, as one to two asteroids get close enough to our planet every year for analysis. Further, the agency hopes to learn more about asteroid makeup through its planned Origins-Spectral Interpretation-Resource Identification-Security-Regolith Explorer (OSIRIS-REx) mission, which is on its way to asteroid Bennu in 2018 after a launch in 2016.

All of this, of course, is dependent on NASA’s budgetary situation for the years to come, which in turn depends on support in Congress.

June 12, 2014April 26, 2016 by Bob King

Awesome Radar Images Reveal Asteroid 2014 HQ124’s Split Personality

Radar delay-Doppler images of asteroid 2014 HQ124. The Earth and radar transmitter are toward the top of each frame. Each frame has the same orientation, delay-Doppler dimensions, resolution (3.75 m by 0.0125 Hz), and duration (10 minutes). Arecibo images appear on the top row and Goldstone images appear on the other rows: Arecibo Observatory capabilities eliminated the "snow" visible in the other images.There is a gap of about 35 minutes between rows 1 and 2. Credit: Marina Brozovic and Joseph Jao, Jet Propulsion Laboratory/ Caltech/ NASA/ USRA/ Arecibo Observatory/ NSF

On June 8, the 370-meter (about 1,300-ft.) asteroid 2014 HQ124 breezed by Earth at a distance of just 800,000 miles (1.3 million km). Only hours after closest approach, astronomers used a pair of radio telescopes to produce some of the most detailed images of a near-Earth asteroid ever obtained. They reveal a peanut-shaped world called a ‘contact binary’, an asteroid comprised of two smaller bodies touching.

About one in six asteroids in the near-Earth population has this type of elongated or “peanut” shape. It’s thought that contact binaries form when two or more asteroids get close enough to touch and ‘stick’ together through their mutual gravitational attraction. Asteroid 25143 Itokawa, visited and sampled by the Japanese spacecraft Hayabusa in 2005, is another member of this shapely group.

Radar observations of asteroid 2014 HQ124 seen here in video

The 21 radar images were taken over a span of four hours and reveal a rotation rate of about 20 hours. They also show features as small as about 12 feet (3.75 meters) wide. This is the highest resolution currently possible using scientific radar antennas to produce images. Such sharp views were made possible for this asteroid by linking together two giant radio telescopes to enhance their capabilities.

Astronomers used the 230-foot (70-meter) Deep Space Network antenna at Goldstone, Calif. to beam radar signals at the asteroid which reflected them back to the much larger 1000-foot (305-meter) Arecibo dish in Puerto Rico. The technique greatly increases the amount of detail visible in radar images.

Aerial view of the 1,000-foot dish at Arecibo Observatory. Credit: NOAA

Arecibo Observatory and Goldstone radar facilities are unique for their ability to resolve features on asteroids, while most optical telescopes on the ground would see these cosmic neighbors simply as unresolved points of light. The radar images reveal a host of interesting features, including a large depression on the larger lobe as well as two blocky, sharp-edged features at the bottom on the radar echo (crater wall?) and a small protrusion along its long side that looks like a mountain. Scientists suspect that some of the bright features visible in multiple frames could be surface boulders.

“These radar observations show that the asteroid is a beauty, not a beast”, said Alessondra Springmann, a data analyst at Arecibo Observatory.

A single radar image frame close-up view of 2014 HQ124. Credit: Marina Brozovic and Joseph Jao, Jet Propulsion Laboratory/ Caltech/ NASA/ USRA/ Arecibo Observatory/ NSF — A single radar image frame close-up view of 2014 HQ124. Credit: NASA

The first five images in the sequence (top row in the montage) represent the data collected by Arecibo, and demonstrate that these data are 30 times brighter than what Goldstone can produce observing on its own. There’s a gap of about 35 minutes between the first and second rows in the montage, representing the time needed to switch from receiving at Arecibo to receiving at the smaller Goldstone station.

If you relish up-close images of asteroids as much as I do, check out NASA’s Asteroid Radar Research site for more photos and information on how radar pictures are made.

June 11, 2014March 1, 2017 by Fraser Cain

Why Isn’t the Asteroid Belt a Planet?

It seems like there’s a strange gap in between Mars and Jupiter filled with rocky rubble. Why didn’t the asteroid belt form into a planet, like the rest of the Solar System?

Beyond the orbit of Mars lies the asteroid belt its a vast collection of rocks and ice, leftover from the formation of the solar system. It starts about 2 AU, ends around 4 AU. Objects in the asteroid belt range from tiny pebbles to Ceres at 950 km across.

Star Wars and other sci-fi has it all wrong. The objects here are hundreds of thousand of kilometers apart. There’d be absolutely no danger or tactical advantage to flying your spacecraft through it.

To begin with, there actually isn’t that much stuff in the asteroid belt. If you were to take the entire asteroid belt and form it into a single mass, it would only be about 4% of the mass of our Moon. Assuming a similar density, it would be smaller than Pluto’s moon Charon.

There’s a popular idea that perhaps there was a planet between Mars and Jupiter that exploded, or even collided with another planet. What if most of the debris was thrown out of the solar system, and the asteroid belt is what remains?

We know this isn’t the case for a few of reasons. First, any explosion or collision wouldn’t be powerful enough to throw material out of the Solar System. So if it were a former planet we’d actually see more debris.

Second, if all the asteroid belt bits came from a single planetary body, they would all be chemically similar. The chemical composition of Earth, Mars, Venus, etc are all unique because they formed in different regions of the solar system. Likewise, different asteroids have different chemical compositions, which means they must have formed in different regions of the asteroid belt.

In fact, when we look at the chemical compositions of different asteroids we see that they can be grouped into different families, with each having a common origin. This gives us a clue as to why a planet didn’t form where the asteroid belt is.

If you arrange all the asteroids in order of their average distance from the Sun, you find they aren’t evenly distributed. Instead you find a bunch, then a gap, then a bunch more, then another gap, and so on. These gaps in the asteroid belt are known as Kirkwood gaps, and they occur at distances where an orbit would be in resonance with the orbit of Jupiter.

Jupiter’s gravity is so strong, that it makes asteroid orbits within the Kirkwood gaps unstable. It’s these gaps that prevented a single planetary body from forming in that region. So, because of Jupiter, asteroids formed into families of debris, rather than a single planetary body.

What do you think? What’s your favorite object in the asteroid belt. Tell us in the comments below.

June 11, 2014December 23, 2015 by Elizabeth Howell

Could Asteroids Solve The Fuel Problem In Space? Planetary Resources Video

A screenshot from Planetary Resources' "The Trillion Dollar Market: Fuel in Space From Asteroids." Credit: Planetary Resources/YouTube (screenshot)

While we as a community love exploring space, we also recognize it can be expensive. Launch costs, manufacturing and keeping a mission going all take money, which is why NASA (for example) runs reviews every couple of years to figure out which ongoing missions are providing the best return.

Planetary Resources — one of the companies that wants to mine asteroids, and is searching for them with NASA — has produced a new video envisioning a solution to that problem: harvesting fuel from asteroids. Leaving the legal concerns aside, the company points out this could be a way of better opening up exploration of the solar system.

“In space one resource above all others is extraordinarily expensive and without cheap access to it, growth is limited…FUEL,” Planetary Resources wrote. “The catalyst for rapid expansion into every frontier in history has been access to cheap, local resources. And in space, access to rocket fuel is currently neither cheap, nor local.

“But on asteroids,” it continued, “abundant quantities of hydrogen and oxygen can be used to create rocket fuel, the same stuff used by the space shuttle. This allows companies like Vivisat fuel spacetugs that will be used to keep satellites in their Geostationary slots, or fuel up your spacecraft before zooming off to Mars. The possibilities are endless!”

How Sentinel Will Hunt for Hidden Asteroids

Asteroids of various sizes whiz past our planet all the time. Some we know about, but many we don’t, and new ones are identified on an almost weekly basis. (In fact one such recently-discovered asteroid named 2014 HQ214, an object the length of an aircraft carrier, will pass us at a mere 3 lunar distances ~~today~~ June 8… watch live coverage here.) And, of course, some actually do impact Earth, and if they are large enough the results can be quite… energetic, to put it lightly.

While there aren’t yet any programs in place that can prevent a large asteroid impact from happening, there are some that are at least on the lookout for potential impactors. The B612 Foundation’s privately-funded Sentinel mission is one of them and, once launched and placed in orbit around the Sun in 2018, will hunt for near-Earth asteroids down to about 140 meters in size using the most advanced infrared imaging technology… and no federal budget cuts or red tape to worry about.

The video above, produced by B612 Foundation’s primary contractor Ball Aerospace, shows how Sentinel will work, and why development has been going so well.

“I see this as the wave of the future — the ability for non-governmental organizations to put together the funding, working with outstanding technical organizations like Ball Aerospace, and produce space missions where the government isn’t involved and where the price is much, much less, and we still get the same kind of great information.”

– Dr. Scott Hubbard, B612 Program Architect and former director of the NASA Ames Research Center

Learn more about the B612 Foundation here.

June 1, 2014December 28, 2015 by Bob King

Asteroid 2014 KH39 Zips Just 1.1 LD from Earth – Watch it LIVE June 3

Near Earth asteroid 2014 KH39, discovered on May 24, 2014, is the faint 'star' in the crosshairs in this photo made on May 31. The telescope tracked the asteroid, so the stars are trailed. The streak is a satellite. Credit: Gianluca Masi

Got any plans Tuesday? Good. Keep them but know this. That day around 3 p.m. CDT (20:00 UT) asteroid 2014 KH39 will silently zip by Earth at a distance of just 272,460 miles (438,480 km) or 1.14 LDs (lunar distance). Close as flybys go but not quite a record breaker. The hefty space rock will buzz across the constellation Cepheus at nearly 25,000 mph (11 km/sec) near the Little Dipper at the time.

Observers in central Europe and Africa will have dark skies for the event, however at magnitude +17 the asteroid will be too faint to spot in amateur telescopes. No worries. The Virtual Telescope Project, run by astrophysicist Gianluca Masi, will be up and running with real-time images and live commentary during the flyby. The webcast begins at 2:45 p.m. CDT June 3.

2014 KH39 was discovered on May 24 by Richard Kowalski of the Catalina Sky Survey. (Kowalski is the same astronomer who discovered asteroid 2008 TC3, the small asteroid that impacted in Sudan in 2008). Further observations by the CSS and additional telescopes like Pan-STARRS 1 in Hawaii nailed down its orbit as an Earth-approacher with an approximate size of 72 feet (22 meters). That’s a tad larger than the 65-foot Chelyabinsk asteroid that exploded into thousands of small stony meteorites over Russia in Feb. 2013.

Diagram showing the orbit of 2014 KH39. Yellow shows the portion of its orbit above the plane of Earth’s orbit (grey disk); blue is below the plane. When farthest, the asteroid travels beyond Mars into the asteroid belt. It passes closest to Earth around 3 p.m. CDT June 3. Credit: IAU Minor Planet Center

Since this asteroid will safely miss Earth we have nothing to fear from the flyby. I only report it here to point out how common near-Earth asteroids are and how remarkable it is that we can spot them at all. While we’re a long ways from finding and tracking all potentially hazardous asteroids, dedicated sky surveys turn up dozens of close-approaches every year. On the heels of 2014 KH39, the Earth-approaching asteroid 2014 HQ124 will pass 3.3 LDs away 5 days later on June 8. With a diameter estimated at more than 2,100 feet (650-m) it’s expected to become as bright as magnitude +13.7. Southern hemisphere observers might track it with 8-inch and larger telescopes as its speeds across Horologium and Eridanus the morning before closest approach.

The chart shows the cumulative known total of near-Earth asteroids (NEAs) vs. time. The blue area shows all NEAs while the red shows those roughly 1 km and larger. Thanks to many surveys underway as well as help from space probes like the Wide-Field Infrared Explorer (WISE), discovery totals have been ramping up. Credit: NASA — The chart shows the cumulative known total of near-Earth asteroids (NEAs) vs. time. The blue area shows all NEAs while the red shows those roughly 1 km and larger. Thanks to many ground-based surveys underway as well as space probes like the Wide-field Infrared Survey Explorer (WISE), discovery totals have ramped up in recent years. There are probably millions of NEOs smaller than 140 meters waiting to be discovered. Credit: NASA

Perusing the current list of upcoming asteroid approaches, these two will be our closest visitors at least through early August. Near-Earth objects (NEOs) are comets and asteroids whose original orbits have been re-worked by the gravity of the planets – primarily Jupiter – into new orbits that allow them to approach relatively close to Earth. The ones we’re most concerned about are a subset called Potentially Hazardous Asteroids or PHAs, defined as objects that approach within 4.65 million miles (7.48 million km) of Earth and span 500 feet (150-m) across or larger. The key word here is ‘potential’. PHAs won’t necessarily hit the Earth – they only have the potential to do so over the vastness of time. On the bright side, PHAs make excellent targets for sampling missions.

Most near-Earth asteroids fall into three classes named after the first asteroid discovered in that class. Apollo and Aten asteroids cross Earth's orbit; Amors orbit just beyond Earth but cross Mars' orbit. Credit: Wikipedia — Most near-Earth asteroids fall into three classes named after the first asteroid discovered in that class. Apollo and Aten asteroids cross Earth’s orbit; Amors orbit just beyond Earth but cross Mars’ orbit. Credit: Wikipedia

As of May 30, 2014, 11,107 near-Earth objects have been discovered with 860 having a diameter of 1 km or larger. 1,481 of them have been further classified as potentially hazardous. NASA’s Near-Earth Object Program estimates that over 90% of NEOs larger than 1 km (the most potentially lethal to the planet) have been discovered and they’re now working to find 90% of those larger than 459 feet (140 meters) across. Little by little we’re getting to better know the neighborhood.

The probability that either 2014 KH39 and 2014 HQ124 will hit Earth on this round is zero. Nor do we know of any asteroid in the near future on a collision course with the planet. Enjoy the day.