The artistic concept of Kepler-186f is the result of scientists and artists collaborating to help imagine the appearance of these distant worlds. Credit: NASA Ames/SETI Institute/JPL-CalTech.
As Etta James once sang in the old standard, “At Last!” And, now planet-searchers are singing the same tune. Kepler mission scientists have just announced the detection of one of the Holy Grails of exoplanet searches: the first Earth-sized planet in the habitable zone of its star. This is a momentous discovery in a long string of amazing exoplanet detections for the Kepler team and the teams of followup observers at the W.M. Keck and Gemini Observatories in Hawai’i. It means, among other things, that worlds similar in many ways to our Earth exist out there.
Earth orbits in the Sun’s habitable zone, which means that it is in a “safe zone” where liquid water can exist on our planet’s surface. Finding a world in the habitable zone of Kepler-186, which is an M-class red dwarf star about 490 light-years away from us, means that this planet could also support liquid water on its surface. And, where there’s water, there’s likely to be life. That doesn’t mean that there IS life on this planet. It’s too early to tell for that. But, it’s an exciting discovery because it means there’s another world out there that could (in some ways) be very like Earth.
The search for water on Mars keeps turning up evidence that something wet once flowed across its surface. Images like this one from the Mars Express orbiter show streamlined islands and narrow gorges that were carved out by fast-moving water sometime in the distant past. This one shows a region near the Vallis Marineris canyon complex that splits the mid-section of the planet. Captured on December 7th, 2013 by the Mars Express cameras, this view is of the Osuga Valles region. It’s an outflow channel that emanates from a region of what planetary scientists call chaotic terrain (that is, chaotic landscapes disrupted in some way).
A perspective view of Osuga Valles on Mars, showing braided river valleys that once carried water across the surface. Courtesy ESA/Mars Express.
The search for water on Mars keeps turning up evidence that water once flowed across its surface. Images like this one from the Mars Express orbiter show streamlined islands and narrow gorges that were carved out by fast-moving water sometime in the distant past. This one shows a region near the Vallis Marineris canyon complex that splits the mid-section of the planet. Captured on December 7th, 2013 by the Mars Express cameras, this view is of the Osuga Valles region. It’s an outflow channel that emanates from a region of what planetary scientists call chaotic terrain (that is, chaotic landscapes disrupted in some way).
So, what caused this scene? The most likely explanation is an episode of chaotic flooding (extremely heavy flash flooding) that sent water and rocks and mud rushing across the landscape and carving out these channels and gullies. The geologic evidence here suggests that there were likely several bouts of flooding, creating these grooved valley floors and islands.
