phproxy url include 24 24h

We recently interviewed Dr. Kevin Grazier, on of the scientist who has worked extensively on the Cassini mission. Here's what he had to tell us about that mission's discoveries.
"My name is Kevin Grazier. I am a planetary scientist, and for my research I do long-term integrations or simulations of early solar system evolution. I'm a former scientist on the Cassini mission and a consultant to several TV series such as Defiance, Falling Skies, the movie Gravity, and formerly, Battlestar Galactica."
What are Cassini's most amazing discoveries?
"Cassini has essentially rewritten the book on the Saturn system. I was on the spacecraft team for 15 years. I worked as a science planner and as the Investigation Scientist on the ISS instrument. (That's Imaging Science Subsystem, not International Space Station.) And of the discoveries we found, I'm trying to think of what I'd call or classify as the most exciting."
"One was predicted -- the fact that it was believed that there could be ice volcanoes on Enceladus. And as a matter of fact, there are volcanoes on Enceladus, or active venting, however you want to look at that. Those vents create the "E" ring, so we have a ring created by material vented off Enceladus. That's pretty exciting, because we see an active object venting material, and there aren't a lot of active objects in the solar system."
"The surface of Titan is really fantastic. We have open oceans or seas of hydrcarbons on Titan. We have the possibility of an open ocean underneath the crust, just like we believe is under the surface of Europa."
"We have one image which seems to capture what might be a volcanic eruption. That's important, because in the outer solar system, planetary science considers ice a rock. What a rock is defined as depends on where you are in the solar system. So in the outer solar system, ice is a rock. All of the moons in the outer solar system except Io have icy crusts. Now, if you have a volcanic eruption on Titan, we have an eruption of magma, and if ice is a rock, that eruption is water. So we have evidence of magma chambers which could be cauldrons of life-giving water."
"How cool is that? How counter-intuitive is that? How science-fiction-y is that? That one of the most interesting places to look for is a lava chamber or magma chamber that could be suitable for sustaining life. I think that's really exciting."
You can follow Dr. Kevin on Twitter here: https://twitter.com/kevingrazier

Read more: http://www.universetoday.com/?p=10799...

We enjoy the light from the Sun during the day, and then the comforting glow of the Moon at night.

But the light coming from the Moon is an illusion.

As you know, you're actually seeing the reflected light from the Sun, bouncing off the Moon which acts like a mirror.

A really terrible mirror.

When astronauts walked on the surface, they reported that it was dark grey, the color of pavement.

Because of its dark color and bumpy surface, it only reflects about 12% of the light that hits it.

Additionally, the amount of light we get from the Moon depends on the point of its orbit.

During its first and last quarters, the Moon is half illuminated, but it's only 8% as bright when it's full.

Just imagine the surface when its only partly illuminated.

With the Sun at a steep angle, the mountains cast long shadows.

This makes the lunar surface much darker than when it's directly illuminated.

During the full Moon, it's so bright that it obscures fainter objects in the night sky.

Many astronomers put their telescopes away during this phase, and wait for it to go away.

When the Moon is highly illuminated, it reflects so much light we can even see it during the day.

The brightness of the daytime sky completely washes out the light from the stars, but the Moon is even brighter, and so we can can see it in the sky during the day.

The Moon follows an elliptical orbit around the Earth, changing its distance and brightness quite a bit.

When it is at its closest point, and it's full, this is known as a supermoon.

This Moon can be 20% brighter than normal.

You've probably experienced how the Moon can cast shadows. In fact, there are three objects in the sky that can cast shadows.

The Sun, of course, the Moon... and Venus.

Venus is the next brightest object in the sky, after the Moon. It reflects 65% of the sunlight that hits it.

Every few months, Venus reaches its brightest time - that's when you can see your shadow.

On a night with no Moon, head far away from city lights.

Let your eyes adjust and watch as your hand casts a shadow on a white piece of paper, illuminated only by Venus.

One last thought on reflected light.

We talked about how bad a mirror the Moon is, reflecting only 12% of the light that hits it. That's nothing.

Saturn's moon Enceladus, on the other hand, reflects about 99% of the light that falls on it. If astronauts ever get the chance to walk on the surface of Enceladus, it'll feel like freshly fallen snow.