Show Date: July 12, 2006 
Pam Eastlick for THE DEEP on line

WHERE THE SUN NEVER SETS

Welcome to The Deep science and technology column where we cover topics from the deep sea to deep space and beyond. Join us each week on Newstalk K57 on Wednesday night from 7 to 8 p.m. for exciting live science expeditions or listen live on our web site www.thedeepradioshow.com

We’ve all talked about that mythical place where the Sun never shines, but did you know there’s a place in the solar system where the Sun always shines? This doesn’t make any sense; of course, every object that orbits the Sun rotates. All of the moons keep the same side turned toward their planet, but that means that they all rotate in reference to the Sun, so every part of them is eventually bathed in sunlight (usually for half the time they take to orbit their planet). So where could you go in the solar system where it was never night? It turns out the answer is really close at hand and it’s intimately tied with another solar system question. Where is the biggest hole?

We discovered the solar system’s largest crater (that we know about so far) in the mid-90’s.

You’d think that if it took that long, the largest impact must be on some obscure outer moon of Neptune or Uranus, but you’d be wrong. The solar system’s biggest and deepest hole is on our own Moon, Luna. Since we’ve been able to see the Moon since we lived in caves, what took us so long? Ah, you’re thinking, it’s on the side of the Moon we can never see, right? Well, no, we’ve had detailed pictures of the Moon’s far side since the 1960’s and there aren’t any gigantic holes there either. So where is this massive crater? Most of you have come up with the answer. The parts of the Moon not seen until the 1990’s are its north and south poles, and the Aitken Basin, the solar system’s biggest impact crater, is at Luna’s south pole. And a mighty hole it is too!

Aitken Basin at Luna’s south pole.

There’s a little spacecraft in orbit around the Moon right now called Smart 1. You haven’t heard much about it because it isn’t one of NASA’s and we Americans tend not to consider the accomplishments of others as newsworthy. Smart 1 was launched by the European Space Agency in 2003 and it’s gathered a lot of information about our neighbor in the last three years.
	Smart 1

If we’re going to settle the Moon, it would really help if we didn’t have to take every drop of water we need with us. Water is very heavy and we can’t live without it. If the Aitken Basin was formed by a comet impact, there’s a very strong possibility that the bottom of the hole is covered with water ice and lots of it. We’ve already crashed one spacecraft into the edge of the Aitken Basin to see if the dirt plowed up by the impact contained water, and the scientists want to crash Smart 1 into the Aiken Basin as well. That was set to happen on 17 August, but the probe would have crashed into the Moon’s night side, limiting our ability to analyze the plum. So, they’re bringing the spacecraft higher above the lunar surface so that it will crash on 3 September in the daylight. Will we see water? Who knows? But I’ll be combing the news to find out.

	Oh, and the Peak of Eternal Light? The Moon rotates virtually straight up and the rim of the solar system’s largest impact crater is quite high above the surrounding landscape. High enough that the tallest points of the rim would be bathed in eternal sunlight. Join us this week on The Deep for a live remote to the Assisted Care Facility where Jim Sullivan will once again be your host. And we’ll also talk about the Peak of Eternal Light.
Peak of Eternal Light.
Credit: Erven J.J. TiJl Press Press (Zwolle, Netherlands)

The Deep is broadcast on Newstalk K57 every Wednesday night at 7:00 p.m. You can also listen live from our web site www.thedeepradioshow.com. Join Jim Sullivan, Pam Eastlick, and Peter Melyan on the deepest radio show on Earth.