Cassini spies Mimas hiding in Saturn’s rings
Credit: NASA / JPL / SSI / Gordan Ugarkovic
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Baked Exoplanet Gets Lab Treatment
Don’t get too excited, an exoplanet hasn’t really been captured from the cosmic wilds. And no, one of NASA’s boffins isn’t really taking a pair of tongs to the upper atmosphere of a strangely tiny “hot-Jupiter” being baked by a Bunsen burner. The doctored photo is actually a fun metaphor for this golden age of exoplanetary science. In particularly, it illustrates what one NASA space telescope is doing to understand the chemistry and dynamics of a particular Jupiter-sized exoplanet located some 385 light-years away.
Of course, it would be preferential if we could directly sample an exoplanet’s atmosphere in a lab, but as all exoplanets orbit stars many light-years from the nearest Bunsen burner, astronomers need to think up novel techniques by which the atmospheres of exoplanets can be remotely probed. Enter the Spitzer Space Telescope, NASA’s premier infrared observatory, the inadvertent hero of exo-atmospheric science!
Launched in 2003, Spitzer was designed to observe the infrared universe — particularly star-forming molecular clouds and distant galaxies — but in 2005 it became famous for detecting infrared emissions from extra-solar planets, namely HD 209458b and TrES-1. Since then, Spitzer has continued to notch up some impressive exoplanetary discoveries.
“When Spitzer launched in 2003, we had no idea it would prove to be a giant in the field of exoplanet science,” said Michael Werner, Spitzer project scientist at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “Now, we’re moving farther into the field of comparative planetary science, where we can look at these objects as a class, and not just as individuals.”
In a new study published in the Astrophysical Journal, astronomers have used Spitzer to watch an exoplanet complete a full orbit around its host star.
Over 6 days, the hot-Jupiter HAT-P-2b passed in front of its star, behind and back in front again. Interestingly, HAT-P-2b’s orbit is highly eccentric, meaning its orbital path takes it only 2.8 million miles from the star’s surface at closest approach and out to 9.3 million miles at its most distant. As a comparison, the solar system’s innermost planet, Mercury, orbits the sun every 88 days and doesn’t come closer than 28 million miles — HAT-P-2b is therefore a roasted planet, where rapid changes in its atmosphere can be expected from extreme heating.
Fortunately, because HAT-P-2b’s orbit is not only compact but also eccentric, astronomers have a wonderful opportunity to see these changes occur over a very short timescale.
This image covers many shallow irregular pits with raised rims, concentrated along ridges and other topographic features. How did these odd features form?
One idea is that they could be from sublimation of shallow lenses of nearly pure ice, but why do the pits have raised rims? They can’t be impact craters with such fortuitous alignment and irregular margins. They aren’t wind-blown deposits because there are many boulders, too big to be moved by the wind. There are younger wind-blown drifts on top of the pits, and there’s no clear connection to volcanism.
Some speculate that there were ancient oceans over this region—could that somehow explain these features? Ancient glaciation is another possibility, perhaps depositing ice-rich debris next to topographic obstacles.Future images of this region may provide clues, but for now this is a mystery.
Astronomers Produce Most Detailed Analysis of Alien Planet’s Atmosphere
Astronomers say they’ve confirmed the presence of water vapor and carbon monoxide in the atmosphere of a giant planet beyond our solar system, thanks to the most detailed spectroscopic scan ever made.
The observations, detailed Thursday on the journal Science’s website, uses a method that could someday be used to sample the air of an alien Earth from light-years away, the researchers said.
Image: An artist’s rendering shows the HR 8799 planetary system at an early stage in its evolution, with HR 8799c in the foreground. That giant planet orbits its parent star at a distance comparable to Pluto’s distance from our sun. Credit: Dunlap Institute for Astronomy and Astrophysics; Mediafarm
“The big surprise was actually that we could do it,” one of the study’s co-authors, Travis Barman of the Lowell Observatory in Arizona, told reporters. “We can actually see the individual lines of these molecules. … I personally felt like we would not be able to do what we have done.”
This isn’t the first time scientists have studied the atmosphere of HR 8799c, a planet about seven times as massive as Jupiter that orbits a star 130 light-years from Earth. The HR 8799 system is special because astronomers can actually pick up the light of several giant planets that orbit outside the glare of their parent star. HR 8799c, for example, follows an orbit similar to the one Pluto traces around our own sun.
That’s what makes it possible for astronomers to get the “chemical fingerprint” of the planet’s atmosphere. One team did it three years ago with an instrument on the European Southern Observatory’s Very Large Telescope in Chile. Another team reported just this week that they did it for four planets in the HR 8799 system using an instrument known as Project 1640 on the Palomar Observatory’s Hale Telescope in California.
Closest ‘Alien Earth’ May Be 13 Light-Years Away
An Earth-like alien planet may reside right in our solar system’s backyard, just 13 light-years or so away, astronomers announced yesterday, Feb 6th.
Image: Artist’s Conception of Planets Orbiting Red Dwarf Star Credit: David A. Aguilar
That number is just an estimate, though, and not based on an exoplanet discovery.
The researchers used data from NASA’s prolific planet-hunting Kepler space telescope, which is staring at more than 150,000 stars simultaneously. Kepler detects planets by measuring the temporary brightness dips caused when the worlds pass in front of, or transit, their stars’ faces from the instrument’s perspective.
3,897 red dwarfs — stars dimmer and smaller than our own sun — and determined that Kepler has identified 95 exoplanet candidates circling them. Three of these candidates are roughly Earth-size and orbit within their stars’ “Goldilocks zone,” where liquid water (and possibly life as we know it) can exist.
Kepler isn’t able to detect every planet circling every star that it’s watching, researchers noted. Many worlds don’t orbit in the right plane for Kepler to observe transits, and the signals of others may be masked by brightness variations inherent to red dwarfs.
Taking this into account, about 6 percent of red dwarfs in the Milky Way galaxy should host Earth-like planets, the astronomers said.
Since about 75 percent of the galaxy’s 100 billion stars are red dwarfs, this translates to an estimated 4.5 billion “alien Earths” spread throughout the galaxy. The research team stressed, however, that this is a tentative figure because the distribution of stars varies widely.
Double Crescent: Neptune and Triton
Credit: NASA / JPL / Emily Lakdawalla)
Neptune was the last planet Voyager 2 passed. As it departed the system in September 1989, it watched the crescent planet (along with its largest moon) diminish. This photo was taken on September 3, about 9 days after the flyby.
This new global view of Earth’s city lights is a composite assembled from data acquired by the Suomi National Polar-orbiting Partnership (NPP) satellite.
Credit: NASA’s Earth Observatory/NOAA/DOD
The data was acquired over nine days in April 2012 and 13 days in October 2012. It took 312 orbits to get a clear shot of every parcel of Earth’s land surface and islands. This new data was then mapped over existing Blue Marble imagery of Earth to provide a realistic view of the planet.
The image was made possible by the satellite’s “day-night band” of the Visible Infrared Imaging Radiometer Suite, which detects light in a range of wavelengths from green to near-infrared and uses filtering techniques to observe dim signals such as city lights, gas flares, auroras, wildfires and reflected moonlight.
The day-night band observed Hurricane Sandy, illuminated by moonlight, making landfall over New Jersey on the evening of Oct. 29. Night images showed the widespread power outages that left millions in darkness in the wake of the storm.
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There may be a hundred billion planetary systems in the galaxy awaiting exploration. Not one of those worlds will be identical to Earth. A few will be hospitable; most will appear hostile. Many will be achingly beautiful. In some worlds there will be many suns in the daytime sky, many moons in the heavens at night, or great particle ring systems soaring from horizon to horizon. Some moons will be so close that their planet will loom high in the heavens, covering half the sky. And some worlds will look out into a vast gaseous nebula, all those skies, rich in distant and exotic constellations, there will be a faint yellow star — perhaps barely seen by the naked eye, perhaps visible only through the telescope — the home star of the fleet of interstellar transports exploring this tiny region of the Milky Way Galaxy.
The themes of space and time are, we have seen, intertwined. Worlds and stars, like people, are born, live and die. The lifetime of a human being measured in decades; the lifetime of the Sun is a hundred million times longer. Compared to a star, we are like mayflies, fleeting ephemeral creatures who live out their whole lives in the course of a single day. From the point of view of a mayfly, human beings are stolid, boring, almost entirely immovable, offering hardly a hint that they ever do anything. From the point of view of a star, a human being is a tiny flash, one of the billions of brief lives flickering tenuously on the surface of a strangely cold, anomalously solid, exotically remote sphere of silicate and iron.
In all these other worlds in space there are events in progress, occurrences that will determine their futures. And on our small planet, this moment in history is a historical branch point as profound as the confrontation of the Ionian scientists with the mystics 2,500 years ago. What we do with our world in this time will propagate down through the centuries and powerfully determine the destiny of our descendants and their fate, if any, among the stars.
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Carl Sagan — Travels in Space and Time — Cosmos
Exoplanet Catalog Reveals 7 Possibly Habitable Worlds
A new catalog aims to list all the known planets in the galaxy that could potentially be habitable to life. The count is at seven so far, with many more to come, researchers said.
Image: More exoplanets than expected in the first year of the Habitable Exoplanets Catalog. Image released Dec. 6, 2012. Credit: PHL @ UPR Arecibo, ESA/Hubble, NASA
The online listing, called the Habitable Exoplanets Catalog, celebrated its first anniversary today (Dec. 5). When it was first released last year, it had two potential habitable planets to its name. According to lead researcher Abel Mendez, the team expected to add maybe one or two more in the catalog’s first year. The addition of five suspected new planets was wholly beyond anyone’s expectations.
“The main purpose is for research, but then I realized that also for the public, it was very important,” said Mendez, director of the University of Puerto Rico at Arecibo’s Planetary Habitability Laboratory.
Tethys may not be tiny by normal standards, but when it is captured alongside Saturn, it can’t help but seem pretty small.
Even Saturn’s rings appear to dwarf Tethys (660 miles, or 1,062 kilometers across), which is in the upper left of the image, although scientists believe the moon to be many times more massive than the entire ring system combined.
This view looks toward the unilluminated side of the rings from about 18 degrees below the ringplane. The image was taken in green light with the Cassini spacecraft wide-angle camera on Aug. 19, 2012.
HiRISE Updates: Fresh New Batch of Gorgeous Geological Art from Mars
1. Stunning Landscape Near Mamers Valles: This region of Mars has been long studied for its evidence of glacial-like flow features. The landscape is dominated by flat top mesas and flat valley floors. But a closer look shows evidence that soil material is flowing ever so gradually from the edges of the mesas out into the valleys.
2. Layers in Northeast Sinus Meridiani: The objective of this image is to examine the exposure of thin layers along the walls of a few-kilometer-wide valley in Sinus Meridiani.
3. Martian Mélange: “Mélange” means a confusing mixture, and is used to describe rocks scraped off the top of a downward-moving tectonic plate in a subduction zone on Earth. On Mars it is probably mostly impact cratering that creates such chaotic mixture of rock types rather than plate tectonics.
The false colors in this image indicate altitude.
Credit: Erich Karkoschka (University of Arizona) and NASA
The green and blue regions show where the atmosphere is clear, allowing sunlight to penetrate deep into Uranus. In the yellow and gray regions, a haze or cloud layer is reflecting sunlight away. Orange and red colors indicate very high clouds, like cirrus clouds on Earth.
“The home planet of an emerging technical civilization, struggling to avoid self-destruction. The Earth travels some 2 and a half million kilometers every day around the Sun; eight times faster than that around the center of the Milky Way Galaxy; and, perhaps, twice faster still as the Milky Way falls toward the Virgo cluster of galaxies. We have always been space travelers.” — Carl Sagan
Image by the Russian Federal Space Agency
