December 2008

Hubble: Best Views of Mars

The Hubble has taken a number of images of Mars, but four sets of pictures are particularly notable. There are two opportunities every year when Mars and Earth are the closest they will be to each other. These biennial close approaches of Mars and Earth are identical; they vary every year, because the orbit of Mars around the Sun is extremely elliptical; the close approaches to Earth can range from 35 million to 63 million miles. When Mars and Earth are directly aligned, at their closest, they are said to be in "opposition." There's a super explanation here, even though the most recent example is from 2001.

The first, and in some ways, still the most stunning, was taken in June of 2001. Also be sure to take a look at this detailed image with call-outs labeling the more interesting features.

Ganymede: Now You See It, Now You Don't

Yesterday NASA released a nifty photo of Jupiter's largest moon, Ganymede, immediately before Ganymede seems to disappear behind Jupiter. Ganymede makes a complete orbit around Jupiter every seven days, but because Ganymede's orbit is tilted, from Earth's perspective, it looks as if Jupiter's moon passes in front of Jupiter, then disappears behind the "dark side" of the massive planet, only to reappear again later. Ganymede is not nearly as tiny as the image would suggest. In fact Ganymede is larger than the planet Mercury, but Jupiter is so huge that it dwarfs Ganymede, making the moon seem tiny even though it is the largest moon in the solar system, larger even than Earth's own satellite.

Hubble Finds CO2 on HD 189733b

Researchers at Nasa's Jet Propulsion Laboratory report that the Hubble Space Telescope has found CO2 on a planet outside our solar system. HD 189733b is unlikely to actually harbor extraterrestrial life, being a Jovian class planet with a surface temperature of 1,292 degrees F. But the successful detection bodes well for our search for extraterrestrial life. Although Hubble was originally designed to observe distant stars and galaxies, researcher Mark Swain discovered that he could use its infrared imaging and multi-object spectrometer to identify gases. Using what is called the "secondary eclipse method," Swain waits for the target planet to be eclipsed by its parent star, and compares the light spectra before and after the eclipse.

We were so eager to ask whether we could . . .

... we didn't bother to ask whether we should. - Jeff Goldblum, Jurassic Park ................... Awesome site. What's the penalty for a philosophical interlude? :- ) I'll brave it, amigos ... there's a high correlation (> 0.80, I'd say) between interest in astronomy and interest in science fiction. The SETI folks are interested in astronomy, it would seem. The Hubble Telescope is relevant to those perplexed by The Great Silence. If philosophy ain't your thang, please feel free to scroll past. If it is, here's my $0.02... (Image source: engadget)
"Thou shalt not make a machine in the image of man" - Frank Herbert, Dune series.