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
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.

There Are Now Officially Over 1,000 Confirmed Exoplanets!

More than 1,000 exoplanets have been confirmed and cataloged (PHL @ UPR Arecibo)

It was just last week that we reported on the oh-so-close approach to 1,000 confirmed exoplanets discovered thus far, and now it’s official: the Extrasolar Planets Encyclopedia now includes more than 1,000! (1,010, to be exact.)

21 years after the first planets beyond our own Solar System were even confirmed to exist, it’s quite a milestone!

The milestone of 1,000 confirmed exoplanets was surpassed on October 22, 2013 after twenty-one years of discoveries. The long-established and well-known Extrasolar Planets Encyclopedia now lists 1,010 confirmed exoplanets.

Not all current exoplanet catalogs list the same numbers as this depends on their particular criteria. For example, the more recent NASA Exoplanet Archive lists just 919. Nevertheless, over 3,500 exoplanet candidates are waiting for confirmation.

The first confirmed exoplanets were discovered by the Arecibo Observatory in 1992. Two small planets were found around the remnants of a supernova explosion known as a pulsar. They were the surviving cores of former planets or newly formed bodies from the ashes of a dead star. This was followed by the discovery of exoplanets around sun-like stars in 1995 and the beginning of a new era of exoplanet hunting.

A "Periodic Table of Exoplanets" as listed by the Extrasolar Planets Encyclopedia (PHL)
A “Periodic Table of Exoplanets” as listed by the Extrasolar Planets Encyclopedia (PHL)

(The first exoplanets to be confirmed were two orbiting pulsar PSR B1257+12, 1,000 light-years away. A third was found in 2007.)

Exoplanet discoveries have been full of surprises from the outset. Nobody expected exoplanets around the remnants of a dead star (i.e. PSR 1257+12), nor Jupiter-size orbiting close to their stars (i.e. 51 Pegasi). We also know today of stellar systems packed with exoplanets (i.e. Kepler-11), around binary stars (i.e. Kepler-16), and with many potentially habitable exoplanets (i.e. Gliese 667C).

Read more: Earthlike Exoplanets are All Around Us

“The discovery of many worlds around others stars is a great achievement of science and technology. The work of scientists and engineers from many countries were necessary to achieve this difficult milestone. However, one thousand exoplanets in two decades is still a small fraction of those expected from the billions of stars in our galaxy. The next big goal is to better understand their properties, while detecting many new ones.”

– Prof. Abel Mendéz, Associate Professor of Physics and Astrobiology, UPR Arecibo

Source: Press release by Professor Abel Méndez at the Planetary Habitability Laboratory (PHL) at Arecibo

Read more: Kepler Can Still Hunt For Earth-Sized Exoplanets

While not illustrating the full 1,010 lineup, this is still a mesmerizing visualization by Daniel Fabrycky of 885 planetary candidates in 361 systems as found by the Kepler mission. (I for one am looking forward to the third installment!)

Of course, scientists are still hunting for the “Holy Grail” of extrasolar planets: an Earth-sized, rocky world orbiting a Sun-like star within its habitable zone. But with new discoveries and confirmations happening almost every week, it’s now only a matter of time. Read more in this recent article by Universe Today writer David Dickinson.

Could Cassini See You On “The Day The Earth Smiled?”

The face of Earth aimed toward Cassini during imaging on July 19, 2013

So along with the rest of the world, you smiled. You waved. You went outside on July 19, wherever you were, and looked upwards and out into the solar system knowing that our robotic representative Cassini would be capturing a few pixels’ worth of photons bouncing off our planet when they eventually reached Saturn, 900 million miles away. But did Cassini actually capture any photons coming from where you were? The image above will tell you.

Assembled by the Planetary Habitability Laboratory at the University of Puerto Rico at Arecibo (where the enormous 305-meter radio telescope is located) this image shows what side of Earth was facing Cassini when its “pale blue dot” images were obtained, at approximately 22:47 UTC (Cassini time.)

Didn’t make it into Cassini’s photo? That’s ok… maybe MESSENGER had already caught you earlier that very same day:

The view of Earth seen by MESSENGER from Mercury on July 19, 2013
The view of Earth seen by MESSENGER from Mercury on July 19, 2013

Before Cassini took its images — several hours before, in fact — the MESSENGER spacecraft was holding some photo shoots of its own from 61 million miles in the other direction!

The image above shows the side of Earth that was facing Mercury on the morning of July 19, 2013, when MESSENGER was acquiring images in our direction during a hunt for any possible satellites of the innermost planet.

Earth was as bright (-4.8 magnitude) as the maximum brightness of Venus at the moment the image was taken from Mercury.

Of course, in both series of images specific details of our planet can’t be made out — Earth was barely more than a pixel in size (regardless of any bloom caused by apparent brightness.) Clouds, countries, continents, oceans… the entire population of our world, reduced to a single point of light — a “mote of dust suspended in a sunbeam.”

For both portrayals, high-resolution black and white images from the GOES East and Meteosat meteorological satellites were combined with color information from NASA Visible Earth to generate true-color images of our planet as it would have looked to each respective imaging spacecraft… if they had the impossibly-precise optics to resolve Earth from such distances, of course.

But it’s ok that they don’t… we can still use our imaginations.

Read more here on the PHL’s news release.

Earth from the geostationary weather satellite GOES East on July 19, 2013 at 5 PM EST. This is approximately the view that Cassini would have had of Earth during imaging.
Earth from the geostationary weather satellite GOES East on July 19, 2013 at 5 PM EST. This is approximately the view that Cassini would have had of Earth during imaging.

Image credits: PHL @ UPR Arecibo, NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington, NERC Satellite Station, Dundee University, Scotland. Thanks to Prof. Abel Méndez (PHL/UCR) for the heads-up on these.

Earth-Passing Asteroid is “An Entirely New Beast”

Radar images of asteroid 1998 QE2 and its satellite on June 7. Each frame in the animation is a sum of 4 images, spaced apart by about 10 minutes. (Arecibo Observatory/NASA/Ellen Howell)

On the last day of May 2013 asteroid 1998 QE2 passed relatively closely by our planet, coming within 6 million kilometers… about 15 times the distance to the Moon. While there was never any chance of an impact by the 3 km-wide asteroid and its surprise 750 meter satellite, astronomers didn’t miss out on the chance to observe the visiting duo as they soared past as it was a prime opportunity to learn more about two unfamiliar members of the Solar System.

By bouncing radar waves off 1998 QE2 from the giant dish at the Arecibo Observatory in Puerto Rico, researchers were able to construct visible images of the asteroid and its ocean-liner-sized moon, as well as obtain spectrum data from NASA’s infrared telescope in Hawaii. What they discovered was quite surprising: QE2 is nothing like any asteroid ever seen near Earth.

The Arecibo radar observatory in Puerto Rico (Image courtesy of the NAIC - Arecibo Observatory, a facility of the NSF)
The 305-meter dish at Arecibo Observatory in Puerto Rico (Image courtesy of the NAIC – Arecibo Observatory, a facility of the NSF)

Both Arecibo Observatory and NASA’s Goldstone Deep Space Communications Complex in California are unique among telescopes on Earth for their ability to resolve features on asteroids when optical telescopes on the ground merely see them as simple points of light. Sensitive radio receivers collect radio signals reflected from the asteroids, and computers turn the radio echoes into images that show features such as craters and, in 1998 QE2’s case, a small orbiting moon.

QE2’s moon appears brighter than the asteroid as it is rotating more slowly; thus its Doppler echoes compress along the Doppler axis of the image and appear stronger.

Of the asteroids that come close to Earth approximately one out of six have moons. Dr. Patrick Taylor, a USRA research astronomer at Arecibo, remarked that “QE2’s moon is roughly one-quarter the size of the main asteroid,” which itself is a lumpy, battered world.

Dr. Taylor also noted that our own Moon is a quarter the size of Earth.

QE2’s moon will help scientists determine the mass of the main asteroid and what minerals make up the asteroid-moon system. “Being able to determine its mass from the moon helps us understand better the asteroid’s material,” said Dr. Ellen Howell, a USRA research astronomer at Arecibo Observatory who took both radar images of the asteroid at Arecibo and optical and infrared images using the Infrared Telescope Facility in Hawaii. While the optical images do not show detail of the asteroid’s surface, like the radar images do, instead they allow for measurements of what it is made of.

“What makes this asteroid so interesting, aside from being an excellent target for radar imaging,” Howell said, “is the color and small moon.”

Radar images of asteroid 1998 QE2 (bottom) and its satellite (top) on June 6.
Radar images of asteroid 1998 QE2 and its satellite (top) on June 6. (Arecibo Observatory/NASA/Ellen Howell)

“Asteroid QE2 is dark, red, and primitive – that is, it hasn’t been heated or melted as much as other asteroids,” continued Howell. “QE2 is nothing like any asteroid we’ve visited with a spacecraft, or plan to, or that we have meteorites from. It’s an entirely new beast in the menagerie of asteroids near Earth.”

Spectrum of 1998 QE2 taken May 30 at the NASA Infrared Telescope Facility (IRTF) on Mauna Kea was “red sloped and linear,” indicating a primitive composition not matching any meteorites currently in their collection.

For more radar images of 1998 QE2, visit the Arecibo planetary radar page here.

Source: Universities Space Research Association press release.

How Big Are Galaxies?

Galaxy size comparison chart by astrophysicist Rhys Taylor

I’m going to refrain from the initial response that comes to mind… actually, no I won’t — they’re really, really, really big!!!!

</Kermit arms>

Ok, now that that’s out of the way check out this graphic by Arecibo astrophysicist Rhys Taylor, which neatly illustrates the relative sizes of 25 selected galaxies using images made from NASA and ESA observation missions… including a rendering of our own surprisingly mundane Milky Way at the center for comparison. (Warning: this chart may adversely affect any feelings of bigness you may have once held dear.) According to Taylor on his personal blog, Physicists of the Caribbean (because he works had worked at the Arecibo Observatory in Puerto Rico) “Type in ‘asteroid sizes’ into Google and you’ll quickly find a bunch of  images comparing various asteroids, putting them all next to each at the same scale. The same goes for planets and stars. Yet the results for galaxies are useless. Not only do you not get any size comparisons, but scroll down even just a page and you get images of smartphones, for crying out loud.” So to remedy that marked dearth of galactic comparisons, Taylor made his own. Which, if you share my personal aesthetics, you’ll agree is quite nicely done.

“I tried to get a nice selection of well-known, interesting objects,” Taylor explains. “I was also a little limited in that I needed high-resolution images which completely mapped the full extent of each object… still, I think the final selection has a decent mix, and I reckon it was a productive use of a Saturday.” And even with the dramatic comparisons above, Taylor wasn’t able to accurately portray to scale one of the biggest — if not the biggest — galaxies in the observable universe: IC 1101.

For an idea of how we measure up to that behemoth, he made this graphic:

Galaxy sizes including IC 1101, the largest-known galaxy. Click for a zoomable version. (Credit: Rhys Taylor)
Galaxy sizes including IC 1101, the largest-known galaxy. Click for a zoomable version. (Credit: Rhys Taylor)

That big bright blur in the center? That’s IC 1101, the largest known galaxy — in this instance created by scaling up an image of M87, another supersized elliptical galaxy that just happens to be considerably closer to our own (and thus has had clearer images taken of it.) But the size is right — IC 1101 is gargantuan.

At an estimated 5.5 million light-years wide, over 50 Milky Ways could fit across it! And considering it takes our Solar System about 225 million years to complete a single revolution around the Milky Way… well… yeah. Galaxies are big. Really, really, reallyreally big!

</Kermit arms>

Now if you’ll pardon me, I need to go stop my head from spinning… Read this and more on Rhys Taylor’s blog here, and add Rhys to your awesome astronomy Google+ circles here. And you can find out more about IC 1101 in the video below from Tony Darnell, aka DeepAstronomy:

Researchers Send Mars Some Radar Love

A radar map of Mars’ major volcanic regions created by the Arecibo Observatory in Puerto Rico (John Harmon et al., NAIC)

Even though we currently have several missions exploring Mars both from orbit and on the ground, there’s no reason that robots should be having all the fun; recently a team of radio astronomers aimed the enormous 305-meter dish at Puerto Rico’s Arecibo Observatory at Mars, creating radar maps of the Red Planet’s volcanic regions and capturing a surprising level of detail for Earth-based observations.

The team, led by John Harmon of the National Astronomy and Ionosphere Center, bounced radar waves off Mars from Arecibo’s incredibly-sensitive dish, targeting the volcanic Tharsis, Elysium, and Amazonis regions. Depolarized radar imagery best reveals surface textures; the rougher and less uniform a surface is, the brighter it appears to radar while smooth, flat surfaces appear dark.

What the radar maps portray are very bright — and therefore rough — areas on most of the major volcanoes, although some regions do appear dark, such as the summit of Pavonis Mons.

This likely indicates a covering by smoother, softer material, such as dust or soil. This is actually in line with previous observations of the summit of Pavonis Mons made with the HiRISE camera aboard NASA’s Mars Reconnaissance Orbiter, which showed the summit to appear curiously soft-edged and “out-of-focus”, creating a blurry optical illusion of sorts.

It’s thought that the effect is the result of the build-up of dust over millennia, carried across the planet by dust storms but remaining in place once settled because the Martian wind is just so extremely thin — especially at higher altitudes.

The team also found bright areas located away from the volcanoes, indicating rough flows elsewhere, while some smaller volcanoes appeared entirely dark — again, indicating a possible coating of smooth material like dust or solidified lava flows.

The resolution of the radar maps corresponds to the wavelength of the signals emitted from Arecibo; the 12.6 centimeter signal allows for surface resolution of Mars of about 3 km.

The team’s paper was published in the journal Icarus on July 25. Read more on the Red Planet Report here.

The iconic 305-meter radar telescope at Arecibo Observatory in Puerto Rico

 

Astronomers Measure Sunlight’s Shove

The physical force of sunlight on a moving asteroid has been measured by NASA scientists, providing information on how to better plot these Earth-passing worlds’ future paths.

First proposed by a 19-century Russian engineer, the Yarkovsky effect is the result of an object in space absorbing radiation from the Sun and emitting it as heat, thus creating a slight-but-measurable change in its movement (thanks to Newton’s first law of motion.)

By observing the 1999, 2005 and 2011 close passes of asteroid 1999 RQ36 with the Arecibo and Goldstone radar telescopes, astronomers were able to determine how much the trajectory of the half-kilometer-wide asteroid had changed.

The researchers’ findings revealed that RQ36 shifted by 160 km – about 100 miles – over the course of those 12 years. That deviation is attributed to the Yarkovsky effect. A miniscule force in and of itself, over time it has the ability to move entire worlds (albeit relatively small ones.)

“The Yarkovsky force on 1999 RQ36 at its peak, when the asteroid is nearest the Sun, is only about a half ounce — about the weight of three grapes on Earth,” said Steven Chesley of NASA’s Jet Propulsion Laboratory in Pasadena “Meanwhile, the mass of the asteroid is estimated to be about 68 million tons. You need extremely precise measurements over a fairly long time span to see something so slight acting on something so huge.”

Using measurements of the distance between the Arecibo Observatory in Puerto Rico and RQ36 during its latest pass in 2011 – a feat that was compared by team leader Michael Nolan to “measuring the distance between New York City and Los Angeles to an accuracy of two inches” – Chesley and his team were able to calculate all the asteroid’s near-Earth approaches closer than 7.5 million km (4.6 million miles) from the years 1654 to 2135. 11 such passes were found.

In addition, observation of 1999 RQ36 with NASA’s Spitzer Space Telescope found it to have about the same density as water – that’s light, for an asteroid.

Most likely, RQ36 is a “rubble-pile” form of asteroid, composed of a conglomeration of individual chunks of material held together by gravity.

These findings will be used by NASA scientists to help fine-tune the upcoming OSIRIS-REx mission, which is scheduled to launch in 2016 to rendezvous with 1999 RQ36 and return samples to Earth in 2023. Being a loose collection of rocks is expected to aid in the spacecraft’s sample retrieval process.

The findings were presented on May 19 at the Asteroids, Comets and Meteors 2012 meeting in Niigata, Japan. Read more here.

(Top image: series of radar images of asteroid 1999 RQ36 were obtained by NASA’s Deep Space Network antenna in Goldstone, Calif. on Sept 23, 1999. Credit: NASA/JPL-Caltech)

NASA Prepares for Asteroid’s Close Pass by Earth

Radar image of asteroid 2005 YU55, acquired in April 2010. Credit: NASA/Cornell/Arecibo.

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On Tuesday, November 8, at 6:28 p.m. EST, an asteroid the size of an aircraft carrier will soar past our planet at a distance closer than the Moon… and NASA scientists will be watching!

2005 YU55, a 400-meter (1,300-foot) -wide C-type asteroid, was discovered in December 2005 by Robert McMillan of the Spacewatch Program at the University of Arizona, Tucson. It’s pretty much spherical in shape and dark – darker than charcoal, in fact! Scientists with NASA’s Near-Earth Objects Observation Program will begin tracking it on November 4 using the 70-meter radar telescope at the Deep Space Network in Goldstone, California , as well as with the Arecibo Planetary Radar Facility in Puerto Rico beginning November 8. They will continue tracking 2005 YU55 through November 10.

Animation of 2005 YU55's trajectory on Nov. 8. (NASA/JPL) Click to play.

YU55’s orbit is well understood by scientists. It has come this way before, and although this is the closest it’s come to Earth in at least two centuries it will still be at least 324,600 kilometers (201,700 miles) away at nearest approach. That’s about 85% of the distance to the Moon.

It will approach from the sunward side, making viewing in visible light difficult until after it’s made its closest pass.

Other than the excitement it will most likely cause amongst radar astronomers, 2005 YU55 will have no physical effect on our planet. (There have been some rumors circulating online about this particular asteroid’s upcoming pass, in regards to earthquakes and tidal fluctuations and atmospheric disturbances and other such nonsense… the bottom line is that, like the ill-fated comet Elenin, 2005 YU55 has never been known to pose any threat to Earth.)

“YU55 poses no threat of an Earth collision over, at the very least, the next 100 years,” said Don Yeomans, manager of NASA’s Near-Earth Object Program Office at JPL. “During its closest approach, its gravitational effect on the Earth will be so miniscule as to be immeasurable. It will not affect the tides or anything else.”

The 70m telescope at the Goldstone Deep Space Communications Complex in California's Mojave Desert. (NASA/JPL)

Scientists are very eager though to have a prime opportunity to study this quarter-mile-wide world as it makes its closest pass. The giant telescopes at Goldstone and Arecibo will bounce radar waves off the asteroid, mapping its size and shape, and hopefully obtain some very high-resolution images.

“Using the Goldstone radar operating with the software and hardware upgrades, the resulting images of YU55 could come in with resolution as fine as 4 meters per pixel. We’re talking about getting down to the kind of surface detail you dream of when you have a spacecraft fly by one of these targets.”

– Lance Benner, JPL radio astronomer

Even though YU55 will remain at a safe distance the event is still quite notable. The last time an object this large came so close to Earth was in 1976… and scientists weren’t even aware of it at the time. Luckily we now have programs like the Near-Earth Objects Observations Program – a.k.a. “Spaceguard” –  to identify asteroids like this, hopefully in time to know if they could become a danger to our planet in either the near or distant future.

As of now, no large space rock with Earth’s name on it has been positively identified… but that doesn’t mean there’s nothing out there either. We need to keep diligent, keep looking and, above all, keep funding programs like this. If anything, this pass should serve as a reminder – however harmless – that we certainly are not alone in the solar system!

Read more on the NASA/JPL press release here.

UPDATE: NASA will be holding a live Q&A on 2005 YU55 and other near-Earth objects on November 1 at 2:30 p.m. PDT (5:30 p.m. EDT)… watch live here.

 

 

Arecibo Observatory

courtesy of the NAIC - Arecibo Observatory, a facility of the NSF

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Named after the nearby city in Puerto Rico, the Arecibo Observatory (or Arecibo Radio Telescope) is the largest single-aperture (radio) telescope ever built, 305 m in diameter.

Taking advantage of a karst sinkhole, Cornell University built a spherical reflector out of wire mesh, with receivers at the focus suspended by 18 steel cables strung from three concrete towers on the rim. It took three years to build, and was completed in 1963. Since then it has been upgraded several times; for example, in 1974 perforated aluminum panels replaced the wire mesh, and a Gregorian reflector system added to the receiver mechanism in 1997. Among other things, these upgrades have extended the range of radio wavelengths Arecibo can operate at, both as a radio telescope and for radar astronomy.

Such a visually interesting piece of scientific hi-tech has lead to Arecibo playing a role in many movies and TV shows, from James Bond’s Golden Eye to Contact to X-Files.

Everyone knows about SETI@Home, right? Well, it’s receivers on Arecibo that supply the data which the millions of PCs crunch!

Arecibo has played a key role in many astronomical discoveries, from the rotation period of Mercury (a radar astronomy application, in 1964), to the pulses of the Crab Nebula (1968), to studies of pulsars by Hulse and Taylor (1974) that lead to their Nobel Prize (1993), and to direct imaging of asteroids (another radar astronomy application, first done in 1989).

Due to budget cutbacks and changes in research priorities, the future of Arecibo is uncertain (most of its funding comes from the National Science Foundation); maybe you can find a way to save it?

Here’s the official Arecibo Observatory website; ALFA is a current large-scale astronomical survey being done at Arecibo, in case you don’t already know about SETI@Home, and click here to read more about planetary radar.

Calling All Amateur Astronomers: Help Comb Through Arecibo Data for Gems, Arecibo Spots Triple Asteroid, Arecibo Gets an Upgrade: just three of the many Universe Today stories featuring the Arecibo Observatory!

Some of the ways Arecibo contributes to astronomy are covered in Astronomy Casts The Rise of Supertelescopes, and Across the Electromagnetic Spectrum.

Source: National Astronomy and Ionosphere Center: Arecibo Observatory