The uncertainty of science: New evidence suggests that rather than postulate the existence of dark energy and dark matter, scientists need simply to revise their theories of gravity.
The uncertainty of science: The discoverers of the possibly habitable exoplanet Gliese 581g defend their work against recent science attacks.
According to its manager, the budget troubles of the James Webb Space Telescope will likely keep it on the ground until 2016.
This is terrible news for space-based astrophysics. Until Webb gets launched, NASA will have no money for any other space telescope project. And since all the space telescopes presently in orbit are not expected to be operating at the end of the decade, by 2020 the U.S. space astronomy program will essentially be dead.
Then again, there is the private sector, as Google Lunar X Prize is demonstrating.
More news from Stardust: scientists have now identified what they think is the crater produced by Deep Impact’s impact in 2005. Key quote:
The images revealed a 150-metre-wide crater at the Deep Impact collision point that was not present in 2005. The crater is a subtle feature in the images, but it appears consistently in multiple views from the spacecraft. “So I feel very confident that we did find the [impact] site,” said mission member Peter Schultz of Brown University in Providence, Rhode Island, at a press briefing on Tuesday. The crater’s features are “subdued” rather than sharply defined, like those of craters made in hard materials like rock. “The message is: This surface of the comet where we hit is very weak,” said Schultz. The crater also has a small mound in its middle, indicating that some of the material thrown up by the impact was drawn by the comet’s gravity back down into the crater, he said: “In a way, it partly buried itself.”
The images from Stardust’s flyby of Comet Tempel 1 are now available. I think the image below is the best, as it shows many details of the presently inactive comet surface. Scientists will need a bit of time now to compare these features with those imaged during the flyby of Deep Impact back in 2005.
The first images from Stardust of Comet Tempel 1 have been released. More to come later today.
Update: some glitch is delaying the download of the images. Instead of arriving as programmed, they are arriving in the order taken.
How to watch Stardust’s Comet Tempel 1 flyby tonight.
While politicians argue budgets here on Earth, the NASA probe Stardust is zooming in on its flyby of Comet Tempel 1 tonight.
Which exoplanet should we go to first?
On February 4 a very small asteroid, about a yard in diameter, zipped past the Earth at a distance of only 3,400 miles, closer than any previously recorded asteroid.
Exoplanets galore! The Kepler team announced today the discovery of 68 Earth-sized planets, five in the habitable zone. Key quote:
The discoveries are part of several hundred new planet candidates identified in new Kepler mission science data, released on Tuesday, Feb. 1. The findings increase the number of planet candidates identified by Kepler to-date to 1,235. Of these, 68 are approximately Earth-size; 288 are super-Earth-size; 662 are Neptune-size; 165 are the size of Jupiter and 19 are larger than Jupiter. Of the 54 new planet candidates found in the habitable zone, five are near Earth-sized. The remaining 49 habitable zone candidates range from super-Earth size — up to twice the size of Earth — to larger than Jupiter.
On Monday Stardust did a final mid-course correction in anticipation of its February 14 fly-by of of Comet Tempel 1.
The Wide-Field Infrared Survey Explorer, WISE, has completed its four month extended mission, finishing a scan of the heavens that discovered more than 33,000 asteroids and comets.
Chicken Little was right! The sky is falling!
Here we go again: NASA’s already overbudget Mars Science Laboratory rover is in need of even more cash.
A fizzy ocean on Enceladus? Key quote:
[Scientists believe] that gasses dissolved in water deep below the surface [of Enceladus] form bubbles. Since the density of the resulting “sparkling water” is less than that of the ice, the liquid ascends quickly up through the ice to the surface. “Most of the water spreads out sideways and ‘warms’ a thin surface ice lid, which is about 300 feet thick,” explains Matson. “But some of it collects in subsurface chambers, builds up pressure, and then blasts out through small holes in the ground, like soda spewing out of that can you opened.”
Ikaros takes a picture of Venus.
Hubble detects what may be oldest, most distant object ever seen.
The ESA probe Mars Express flew past the Martian moon Phobos today. Great image!
The University of Kentucky has agreed to pay $125,000 to the astronomer who was denied a job because of academic religious bigotry.
From the American Astronomical Society meeting this week:
A team of astronomers, using the data from the Sloan Digital Sky Survey, calculated the galactic orbits of nearly 40,000 low mass stars. These stars are generally M dwarfs, cool, not very bright, and thus generally somewhat close to the Sun since if they are too far away we would not see them. You can read the abstract here, and download their full poster here [pdf].
For the astronomers, the data told them a great deal about the orbital properties of these stars. Though a majority are in circular orbits between 20 to 30 thousand light years from the galactic center, a small minority are in extremely eccentric orbits that travel far out into the galactic halo, as much 260,000 light years. A few others dive inward, getting within 6000 light years of the galactic center.
What made this poster stand out to me, however, was this quote from the abstract:
In addition, we have identified a number of stars that will pass very close to the Sun within the next [billion years]. These stars form the “Nemesis” family of orbits. Potential encounters with these stars could have a significant impact on orbits of Oort Cloud and Kuiper Belt members as well as the planets. We comment on the probability of a catastrophic encounter within the next [billion years].
All told, they found that 18 low-mass cool M dwarf stars that will eventually pass close to the Sun. One star, SDSS J112612.07+152517.6, an M3 star that is about 2,300 light years away, is in an orbit that has it moving right towards us at about 90,000 miles per hour. Its mass is less than half that of the Sun, about 0.4 solar masses. This figure from the poster roughly illustrates the star’s position relative to our solar system over the next billion years:
The star itself is shown in the inset. The red curve shows its calculated distance from the Sun over time, with the black area above and below showing the uncertainties of the calculation. As you can see, every hundred million years or so the distance between this star and the Sun shrinks, with the very very very rare possibility that the distance will sometimes shrink to zero!
With 18 stars each doing this every few 100 million years or so, the average time between close approaches is about 5 million years. These results suggest that another star passes close enough to our solar system frequently enough to not only disturb the comets in the Oort cloud, but also possibly affect the orbits of the planets in the outer solar system and Kuiper belt. One wonders, for example, if such an event had some influence on Pluto’s strange orbit.
From the AAS meeting, the black hole press conference!
From today’s first press conference at the AAS meeting, astronomers have found that two of the fundamental objects they use as units of measure might not be as reliable a unit of measure as they thought.
From the second press conference at the AAS meeting today, results from the Sloan Digital Sky Survey, which has been surveying the sky in incredible detail over the past eleven years:
All this data will be available for anyone to dig around in.
