A salty sea on Mars. This'm Matt Kaplan. We once again set sail for the

Meridiani planet where the Mars Exploration Rover opportunity has found conclusive evidence

of, my goodness, an ancient sea.

Our guest played a big role in this discovery. Ken Herkinoff is the microscopic imager lead.

Bruce Betts is back from Texas with his whole family

for this week's what's up.

First though, here's Emily.

She's wondering what happens to the Twilight Zone when you live in a double star system.

I'll be right back. Hi, I'm Emily Lockwala with questions and answers. A listener asked, could a planet formed in a binary star system have around the clock sunlight?

There are two ways to have planets in a binary

star system. In the first, the pair of stars orbits close to each other. The two stars would

behave essentially like one large object as far as the pull on the planet is concerned.

The planet would orbit both stars at a great distance.

Such a planet would not have around the clock sunlight,

but residents of the planet would enjoy a spectacular double sun in the daylight sky.

One such planet was discovered in October of 2002 orbiting the star Gamma Cephe. The second way to have a planet in a binary star system

is if the two stars are separated by a great distance and the planet orbits one of the two stars

closely.

What would this guy look like in that situation?

Stay tuned to planetary radio to find out. I have to admit I wondered why the United States Geological Survey or USGS would have a planetary

scientist on staff exploring Mars.

The answer came from Ken Herkinhoff. Ken is a Mars Exploration Rover co-investigator

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