Exoplanet Count Tops 700

An artist's impression of a lone exoplanet transiting its parent star. There are now 700 confirmed alien worlds orbiting other stars (ESO)

An artist's impression of a lone exoplanet transiting its parent star. There are now 700 confirmed alien worlds orbiting other stars (ESO)

On Friday, the Extrasolar Planets Encyclopedia registered more than 700 confirmed exoplanets. Although this is an amazing milestone, it won’t be long until the “first thousand” are confirmed.

There are now more than 700 confirmed exoplanets in the database. The latest addition is the planet HD 100655 b.
— announced via the Exoplanet iPhone app

Only two months ago, the encyclopedia — administered by astrobiologist Jean Schneider of the Paris-Meudon Observatory — registered 600 confirmed alien worlds. Since then, there has been a slew of announcements including the addition of a batch of 50 exoplanets by the European Southern Observatory’s (ESO) High Accuracy Radial velocity Planet Searcher (or HARPS) in September.

The first exoplanet was discovered orbiting a Main Sequence star in 1995, and the rate of exoplanet detections has been accelerating ever since.

It is worth noting that hundreds more candidate exoplanet detections have been made, many of which have been spotted by NASA’s Kepler space telescope. Kepler is staring at the same patch of sky, waiting for alien worlds to cross the line of sight between their parent star and Earth, registering a slight dip in starlight brightness. The 1,235 candidates will be confirmed (or denied) as Kepler awaits future transits.

Detecting the slight dimming of starlight isn’t the only tool exoplanet hunters have to spot these alien worlds. The “radial velocity” method — as employed by systems such as the ESO’s HARPS — can detect the slight “wobble” of stars as orbiting worlds gravitationally “tug” on their parent stars. Both methods have their advantages and both are notching up an impressive exoplanet count. “Microlensing” has also been employed to spot a handful of exoplanets, as has direct imaging.

Exoplanetary studies are amongst the most exciting astronomical projects out there. Not only are we realizing there is a veritable zoo of worlds — some Earth-sized, others many times the mass of Jupiter — we are also pondering the most profound question: could extraterrestrial life inhabit these worlds?

For now, we have no clue, but life as we know it has a habit of springing up where we least expect it, it’s only a matter of time before we start to have some clue as to the existence of life as we don’t know it.

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Earth is no Longer ‘One of a Kind’

For this special little planet, today has been a very big day.

Although we’ve speculated that planets the size of Earth must exist elsewhere in the cosmos, it wasn’t until one of the co-investigators working with the Kepler Space Telescope said he had statistical evidence that worlds of the approximate size of Earth appear to dominate our Milky Way.

We now know Earth isn’t unique.

Alas, this historic news didn’t come without controversy. It was unofficially broken at a TED conference in Oxford earlier this month and only after a recording of a presentation given by Dimitar Sasselov was posted online did the news get out. What’s more, the announcement only became clear when Sasselov referred to a presentation slide depicting a bar chart with the different sizes of exoplanets discovered by Kepler:

A slide from Dimitar Sasselov's TED presentation.

This slide shows the number of exoplanets discovered up until this month, binned by size. We have Jupiter-like exoplanets, Saturn-like exoplanets and Neptune-like exoplanets, all compared with Earth’s radius.

The heart-stopping moment comes when looking at the bar that represents Earth-like exoplanets (i.e. worlds with a radius of below 2 Earth radii, or “<2 Re"). According to Sasselov, Kepler has detected a lot of Earth-like worlds, so many in fact that they dominate the picture. From what we have here, it would appear that around 140 exoplanets are considered to be like Earth.

“The statistical result is loud and clear,” said Sasselov. “And the statistical result is that planets like our own Earth are out there. Our Milky Way galaxy is rich in these kinds of planets.”

But why the controversy? Isn’t this good news?

It would appear that the Kepler co-investigator chose not to wait until the official press release from NASA. He publicized these groundbreaking results in the U.K. at an event where you had to buy tickets to attend. This isn’t usually the stage you’d expect this kind of discovery to be announced — a move that will undoubtedly upset many.

“What is really annoying is that the Kepler folks were complaining about releasing information since they wanted more time to analyze it before making any announcements,” Keith Cowing, of NASAWatch.com, wrote in a SpaceRef article today. “And then the project’s Co-I goes off and spills the beans before an exclusive audience – offshore. We only find out about it when the video gets quietly posted weeks later.”

This sentiment is understandable. Only last month there was some frustration vented at the Kepler team for holding back data on 400 exoplanet candidates. While this might be standard practice — the discovering team should be allowed some time to publish work on any discoveries they have uncovered — telling the world’s scientists they will have to wait until February 2011 before they can get their hands on this invaluable data was a bridge too far.

In light of this, for a Kepler scientist to then jump the gun and disclose a groundbreaking discovery at an international conference without the backing of an official NASA release seems a little hypocritical.

But there is another argument to put out there: Why should anyone sit on such a profound discovery? Perhaps NASA and the Kepler team should have issued an earlier press release announcing to the world that 140 candidate Earth-like worlds have been detected and that further work will need to be done to confirm.

Ultimately, this controversy is just background noise when compared to what we have learned today. Official confirmation or not, Dimitar Sasselov’s message is clear. Although these detections need to be confirmed (hence why these worlds are referred to as “candidates”), it would appear there is an overwhelming preponderance of exoplanets measuring 2 Earth radii or less.

For me, that fact alone is astonishing — the first scientific evidence that worlds of Earth dimensions are not rare.

Earth is no longer unique.

For more, read my Discovery News article, “Kepler Scientist: ‘Galaxy is Rich in Earth-Like Planets‘”

Has Kepler Discovered a New Class of Celestial Object?

The strange objects orbiting the two stars could be mangled white dwarfs... but the jury is still out (NASA)

The first results from NASA’s Kepler exoplanet hunter are in and a perplexing early result has been announced. Yes, the space telescope is working fine, and no, it hasn’t spotted an alien homeworld (yet), but the Kepler team have uncovered something pretty cool.

Kepler may have discovered a new class of celestial object (possibly).

But before we start scratching our heads in confusion or popping the champagne corks in celebration, let’s try to work out what Kepler has observed.

Kepler is currently monitoring 100,000 stars in an effort to seek out extra-solar planets (or “exoplanets”) orbiting these stars. Although Kepler was only launched in March 2009 and early doubts about the observatory’s capabilities caused some low-level concern, Kepler appears to be functioning well and mission controllers are already reporting early results.

Five new exoplanet discoveries by Kepler were announced at the American Astronomical Society (AAS) meeting in Washington D.C. on January 4th, and all seem to have very strange characteristics. Fortunately Discovery News blogger Ray Villard was on the scene at the AAS to hear what the Kepler team had to announce:

In sifting through the Kepler data taken so far, postdoctoral student Jason Rowe found a very curious light signature. When an object passed behind its central star, the light from the system dropped significantly. This means the object — called KOI 74b — must be glowing fiercely with its own light that was blocked out when the object was eclipsed.

Hold up, the light dimmed when the exoplanet passed behind its parent star? Something’s not right here. Kepler detects exoplanets when the worlds pass in front of their parent stars, thereby dimming the starlight, not vice versa!

Actually, this is exactly what’s happened. The “exoplanets” orbiting two otherwise ordinary stars appear to be brighter — and hotter — than their host stars. It’s as if the roles of the stars and the exoplanets have been reversed; the stars are dimming the exoplanetary light as the exoplanet passes behind the star.

Needless to say, there is currently no stellar model that predicts this kind of behavior from extra-solar planetary systems.

This means the object — called KOI 74b — must be glowing fiercely with its own light that was blocked out when the object was eclipsed [...] It is seething at 70,000 degrees Fahrenheit while the parent star is 17,000 degrees Fahrenheit. The strange object can’t be a star because the transit data show that it is no bigger than Jupiter.Ray Villard, Discovery News.

One theory is that KOI 74b (and the other strange object, KOI 81b) could be a white dwarf star that migrated close to its stellar partner. Through binary interactions, the white dwarf was stripped of some of its mass, causing it to puff up and appear like a gas giant exoplanet. That would certainly go to some way of explaining why these two “exoplanets” are so hot.

Of course, the other option is that Kepler has made a groundbreaking discovery and identified a whole new class of celestial object… but I suspect there are other, more mundane reasons for these observations.

I suppose we’ll just have to wait and see until followup observations are made…

Source: Discovery News

A Short Message for Kepler, from Astroengine.com…

The Delta II ignition: Kepler begins its mission on Friday at 10:49pm EST (© United Launch Alliance)

The Delta II ignition: Kepler began its mission on Friday at 10:49pm EST (© United Launch Alliance)

In the 17th Century, Johannes Kepler defined the laws of planetary motion around our star. Now the Kepler space telescope will define the motion of alien worlds around distant stars. Go find us some exoplanets!

I saw this image on The Write Stuff blog at the Orlando Sentinel, and I had to share. It is the moment of ignition of the Delta II rocket from Space Launch Complex-17B at Cape Canaveral Air Force Station, just before lift-off of NASA’s Kepler mission.

For more information and the original image (this one was slightly adjusted to remove compression artefacts), check out The Write Stuff »

Replacing Warheads With Telescopes

Left: The first ever rocket launch from Cape Canaveral, Bumper 2 (based on the V-2 weapon design), was in July 1950. Right: The Kepler space telescope launches onboard a Delta II rocket from Cape Canaveral, March 2009 (NASA)

Left: The first ever rocket launch from Cape Canaveral, Bumper 2 (based on the V-2 weapon design), was in July 1950. Right: The Kepler space telescope launches onboard a Delta II rocket from Cape Canaveral, March 2009 (NASA)

Kepler, the exoplanet-hunting space telescope, successfully launched from Cape Canaveral Air Force Station on top of a Delta II rocket at 10:49 pm EST. In a word: awesome. Unfortunately I missed lift off, but it was good to watch NASA TV as the flames from the first stage receded into the black. Obviously today’s event will come as a huge relief to NASA having lost the Orbital Carbon Observatory (OCO) last month when the Taurus XL upper stage fairing failed to separate, locking the satellite in a doomed sub-orbital trajectory, crashing into the Antarctic Ocean.

The highest any rocket had gone before: A 1947 US V-2 rocket, with nose cone camera, captures the limb of the Earth (NASA)

The highest any rocket had gone before: A 1947 US V-2 rocket, with nose cone camera, captures the limb of the Earth (NASA)

On checking out the NASA homepage, the headline news was obviously about Kepler, but underneath was a fascinating image (left). From the NASA Image of the Day, there’s a vintage piece of spaceflight history. Two images, one facing north, the other south, shows the first view from an altitude of over 100 miles (160 km). The pictures were taken by a camera in the nose cone of an experimental V-2 rocket launched by the US on March 7th, 1947. The V-2 technology, as used by Nazi Germany in World War II, had been captured after the war and developed by US scientists. In this case, the V-2 nose cone housed a camera, rather than an explosive warhead, to carry out the first high altitude atmospheric observations.

The camera returned a series of images to the Earth, and these striking panoramas were constructed, covering a million square miles of our planet’s surface. This was the first time a rocket had been used for rudimentary space science; before this time, rockets only had military applications.

62 years later, almost to the day, a Delta II carries one of the most ambitious NASA projects into orbit, to begin another peaceful application, not studying the atmosphere of our own planet, but to search for other Earths orbiting distant stars.

How far we’ve come

For more about Kepler’s launch and exciting mission, check out Anne Minard’s article on the Universe Today, “Success: Kepler Lifts Off to Look for Other Earths