Stellarium is a free, open-source computer application that runs on every common kind of operating system. Even on my Ubuntu Linux computer it pans smoothly across the sky, and lets you zoom in on particular astronomical bodies (600,000 stars by default, according to the website).

I can’t wait to take this on a laptop into the wilderness, where it can help us learn the constellations and identify stars. Because you can dial up any particular time, serious star-gazers can plan a future night’s viewings or see astronomical events from the past.

The first picture is what you would have seen from our apartment window last night, if Boston weren’t in the way. The second shows Jupiter an hour ago, as it drags its moons across the sky.

By the way, I instantly recognized the narrator as former MIT professor Philip Morrison, who hosted a delightful PBS series in the 1980s called The Ring of Truth.

After you watch the original “Powers of Ten,” be sure to see the Simpsons’ version.

One comment did make me wonder, though:

CEV’s computers will be much more powerful than Apollo’s, enabling all four astronauts to descend to the moon’s surface while their spaceship orbits in autopilot mode.

I can see how this could lead to some problems.

Dave:Hello, HAL, do you read me? Do you read me, HAL?

HAL: Affirmative, Dave, I read you.

Dave: Open the pod bay doors, HAL.

HAL: I’m sorry, Dave, I’m afraid I can’t do that.

Dave: What’s the problem?

HAL: I think you know what the problem is just as well as I do.

Dave: What are you talking about, HAL?

HAL:This mission is too important for me to allow you to jeopardize it.

Dave: I don’t know what you’re talking about, HAL.

HAL: I know you and Frank were planning to disconnect me, and I’m afraid that’s something I cannot allow to happen.

It’s hard to believe it’s been twenty years already. We are farther removed in time from the Challenger explosion than that day was from the moon landing. Yet we’re still flying the same shuttles, which one astronaut recently called a “deathtrap.” Here’s an interesting article on what we’ve learned (or what we think we’ve learned) since then.

That night twenty years ago President Ronald Reagan was eloquent in a way impossible to imagine recent presidents emulating:

There’s a coincidence today. On this day three hundred and ninety years ago, the great explorer Sir Francis Drake died aboard ship off the coast of Panama. In his lifetime the great frontiers were the oceans, and a historian later said, “He lived by the sea, died on it, and was buried in it.” Well, today, we can say of the Challenger crew: Their dedication was, like Drake’s, complete.

The crew of the space shuttle Challenger honored us by the manner in which they lived their lives. We will never forget them, nor the last time we saw them, this morning, as they prepared for their journey and waved goodbye and “slipped the surly bonds of earth” to “touch the face of God.”

Launched little over a year ago, the Messenger spacecraft sped by the Earth last month on its way to Venus and Mercury, using Earth’s gravity like a slingshot to pick up speed. Scientists assembled into a short movie a series of photos from the spacecraft, in which a glistening Earth recedes in the distance.

Check out this image taken from the Spirit Mars Rover. Having landed in January 2004, Spirit’s still trucking along, and it’s just beamed back this picture from atop “Husband Hill.”

Both rovers have lasted about 17 months beyond their original mission. And Spirit is in especially fine form, operating at a power level of 950 watt-hours of electricity per day. That is only 10 watt-hours less than it had after it landed – gusts of wind have probably blown accumulated dust off its solar panels to keep them operating well.

When the United States beat the Soviet Union in the first race to the moon, it confirmed the view, to many, that capitalism rules and communism sucks. But the state that President Reagan called The Evil Empire learned its lesson and embraced capitalism wholeheartedly, in space at least, while NASA ossified into a monstrous, inefficient bureaucracy that would have done Khrushchev proud.

This is good news.

For its next generation of space vehicles, NASA has decided to abandon the design principles that went into the aging space shuttle, agency officials and private experts say.

Instead, they say, the new vehicles will rearrange the shuttle’s components into a safer, more powerful family of traditional rockets.

The plan would separate the jobs of hauling people and cargo into orbit and would put the payloads on top of the rockets – as far as possible from the dangers of firing engines and falling debris, which were responsible for the accidents that destroyed the shuttle Challenger in 1986 and the Columbia in 2003.

I’ve always admired the reliability of the much cheaper Russian Soyuz/Progress rockets. They seem to have several advantages over the American shuttles:

• They have been continuously refined over the years from what works, rather than created from whole cloth.
• They don’t over-emphasize re-usability.
• They don’t try to do too much at once (i.e. simultaneous cargo and human transport).