Yes, boys and girls, we may not be the ‘one of a kind’ world we once thought!
It seems there are a whole bunch of Earth-size planets out there. And by ‘a whole bunch,’ I mean several tens of billions. That’s getting up there, for sure.
The article begins, “NASA’s Kepler space telescope, now crippled and its four-year mission at an end, nevertheless provided enough data to answer its main research question: How many of the 200 billion stars in our galaxy have potentially habitable planets?”
The article continues, “Based on a statistical analysis of all the Kepler observations, University of California, Berkeley, and University of Hawaii, Manoa, astronomers now estimate that one in five stars like the sun have planets about the size of Earth and a surface temperature conducive to life. Given that about 20 percent of stars are sun-like, the researchers say, that amounts to several tens of billions of potentially habitable, Earth-size planets in the Milky Way Galaxy.”
Before we start jumping into our silver Flash Gordon outfits, let’s keep one thing in mind… Earth-size does not automatically mean habitable!!
The team cautioned that Earth-size planets in orbits about the size of Earth’s are not necessarily hospitable to life, even if they reside in the habitable zone around a star where the temperature is similar to that on our planet.
Yes, habitability is a fairly important factor when we’re talking about Earth-like planets. We have to take the Goldilocks Approach. Some are too hot, some are too cold… and some are just right!
“Some may have thick atmospheres, making it so hot at the surface that DNA-like molecules would not survive. Others may have rocky surfaces that could harbor liquid water suitable for living organisms,” Marcy said. “We don’t know what range of planet types and their environments are suitable for life.”
“The primary goal of the Kepler mission was to answer the question, ‘When you look up in the night sky, what fraction of the stars that you see have Earth-size planets at lukewarm temperatures so that water would not be frozen into ice or vaporized into steam, but remain a liquid, because liquid water is now understood to be the prerequisite for life?'” the researchers said. “Until now, no one knew exactly how common potentially habitable planets were around sun-like stars in the galaxy.”
A bit of a side-note here. Amazing scientists are usually lumped together and tagged with general labels like ‘scientists,’ ‘researchers,’ ‘the team’ or, my personal favourite, ‘the study says.’
Let’s take a minute to give credit where credit is most certainly due.
Erik Petigura, UC Berkeley graduate student who led the analysis of the Kepler data.
Andrew Howard, a former UC Berkeley post-doctoral fellow who is now on the faculty of the Institute for Astronomy at the University of Hawaii; and
Geoffrey Marcy, UC Berkeley professor of astronomy.
These really smart and hard-working men, will publish their analysis and findings this week in the online early edition of the journal Proceedings of the National Academy of Sciences.
Journal Reference:
Erik A. Petigura, Andrew W. Howard, and Geoffrey W. Marcy. Prevalence of Earth-size planets orbiting Sun-like stars. PNAS, November 4, 2013 DOI: 10.1073/pnas.1319909110
Sometimes I run into a photograph where it is not so much the tree itself that is so awesome but the way the photographer uses the tree to create a spectacular image.
Explanation: If you climbed this magnificent tree, it looks like you could reach out and touch the North Celestial Pole at the center of all the star trail arcs. The well-composed image was recorded over a period of nearly 2 hours as a series of 30 second long, consecutive exposures on the night of October 5. The exposures were made with a digital camera fixed to a tripod near Almaden de la Plata, province of Seville, in southern Spain, planet Earth. Of course, the graceful star trails reflect the Earth’s daily rotation around its axis. By extension, the axis of rotation leads to the center of the concentric arcs in the night sky. Convenient for northern hemisphere night sky photographers and celestial navigators alike, the bright star Polaris is very close to the North Celestial Pole and so makes the short bright trail in the central gap between the leafy branches.
What happens when two galaxies collide? Although it may take over a billion years, such titanic clashes are quite common. Since galaxies are mostly empty space, no internal stars are likely to themselves collide. Rather the gravitation of each galaxy will distort or destroy the other galaxy, and the galaxies may eventually merge to form a single larger galaxy.
From Tuesday May 14 to Monday 20, I will be out of town for (among other reasons) the Jewish holiday of Shavuot as well as the following Sabbath. See you when I get back!
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(Credit: Petigura/UC Berkeley, Howard/UH-Manoa, Marcy/UC Berkeley)
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