Discovery: Earth-sized Planet candidates in the Habitable zone
Kepler's planet candidates by size. Courtesy of: NASA/Wendy Stenzel
The desire to understand our place in the cosmos has defined us since the dawn of intelligent man. No wonder then – as we have built a greater, more complex and altogether more beautiful conception of the universe – that we ask, peering into the void, “are we alone?” No wonder that shelves have been lined with science fiction works that imagine a cosmos where we are indeed, NOT alone. Where wondrous planets; some Earth-like others entirely alien are populated by life limited only by the laws of physics. Today, on the journey of discovery, we took a small step closer to such a possibility.
On February 2, 2011, NASA‘s space observatory announced that planet-searching telescope, Kepler had found its first Earth-size planet. What’s more it found five planets, all Earth-size planets, orbiting a single star; Kepler-11 (approx. 2000 light years away from Earth).
The count of exoplanets has shot up dramatically after the release of this new data. William Borucki of NASA’s Ames Research Center, Moffett Field, Calif., and the Kepler Mission’s science principal investigator, said the following:
“We went from zero to 68 Earth-sized planet candidates and zero to 54 candidates in the habitable zone – a region where liquid water could exist on a planet’s surface. Some candidates could even have moons with liquid water… Five of the planetary candidates are both near Earth-size and orbit in the habitable zone of their parent stars.”
Of course there will be rigorous follow-ups to confirm that these candidates are actually planets, but Borucki tells us that as it stands, “We have found over twelve hundred candidate planets… more than all the people have found so far in history.” Most of these will be confirmed as planets in the near future. According to project manager Roger Hunter, NASA’s only about half-way through the Kepler Mission, (The 10th Discovery Mission). We can expect many, many more discoveries.
The Kepler 11 Planetary System. Courtesy of http://www.theregister.co.uk/
Some Kepler Statistics
The findings are based on the results of observations conducted May 12 to Sept. 17, 2009 of more than 156,000 stars in Kepler’s field of view, which covers approximately 1/400 of the sky.
- 1,235 planet candidates identified by Kepler to-date.
- 68 are approximately Earth-size.
- 288 are super-Earth-size.
- 662 are Neptune-size.
- 165 are the size of Jupiter.
- 19 are larger than Jupiter.
- 54 new planet candidates found in the habitable zone
- Five are near Earth-sized.
- 49 habitable zone candidates range from super-Earth size — up to twice the size of Earth — to larger than Jupiter.
- 170 stars show evidence of multiple planetary candidates
- Six candidate planets confirmed around Star Kepler-11
- Total of 15 exoplanets, including the smallest known exoplanet, Kepler-10b, confirmed by Kepler to-date
The Science (as NASA tells it)
- Kepler looks for “planet signatures by measuring tiny decreases in the brightness of stars caused by planets crossing in front of them – this is known as a transit.”
- “Transits of planets in the habitable zone of sun-like stars occur about once a year”. They “require three transits for verification”.
- “It is expected to take three years to locate and verify Earth-size planets orbiting sun-like stars.
- Some planets have the “density of Styrofoam and others are denser than iron.”
- Discovered “tremendous variations in the structure of the confirmed planets – The Earth’s density is in between.”
Click image for full-resolution. Kepler's planet candidates as of Feb. 1, 2011. Courtesy of: NASA/Wendy Stenzel
What does it mean?
In a nut shell. There are loads of planets ou there, and more importantly – a greater chance of LIFE beyond Earth. Borucki said:
“The fact that we’ve found so many planet candidates in such a tiny fraction of the sky suggests there are countless planets orbiting stars like our sun in our galaxy… Kepler can find only a small fraction of the planets around the stars it looks at because the orbits aren’t aligned properly. If you account for those two factors, our results indicate there must be millions of planets orbiting the stars that surround our sun.”
The Future
The future is bright and exciting:
“In the coming years, Kepler’s capabilities will allow us to find Earth-size planets in the habitable zone of other stars. Future missions will be developed to study the composition of planetary atmospheres to determine if they are compatible with the presence of life. The design for these missions depends of Kepler finding whether Earth-size planets in the habitable zone are common or rare.”
Watch out for an Urban Times interview by Hal Hodson with renowned planetary scientist and astrophysicist Dr. Sara Seager.
- An Artists impression of the Kepler-11 System. Stunning. Courtesy of: www.theregister.co.uk
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