We Are Stardust

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I've been watching the BBC program Stargazing on TV this week, and I have to say that they did a much better job this year than last. As well as stunning live views of the Northern Lights over three nights, and interviews with some ex-astronauts as well as a lady from the Cassini imaging team, viewers discovered a previously unknown galaxy. I guess that's what you call an interactive experience.

I tend to be something of an armchair stargazer. I watch all the astronomy documentaries, and never miss "The Sky at Night" - thankfully the BBC changed their mind about dropping it after Patrick Moore passed away. We do have a telescope, but it seems to rarely see the light of day (or, more accurately, the dark of night). It's rather like the guitar sitting forlornly in the corner of the study. Both are waiting for me to retire so I have endless hours of free time.

Of course, astronomy is like most physical sciences. Some things you can easily accept, such as the description and facts about our own solar system. Though looking at photos of the surface of another planet is a little un-nerving, and it requires a stretch of the imagination to accept that you're not looking at a film set in Hollywood or a piece of the Mojave desert. And the fact that they say they can tell what the weather is like on some distant Earth-like planet in a far-off galaxy seems to be stretching the bounds of possibility.

They also had to mention the old "where's all the missing stuff" question again. Not only do we not know where 95% of the mass of every galaxy (including our own) is, but we have no idea what the dark matter that they use to describe this missing stuff actually is. Though there was an interesting discussion with the Gaia team, who reckon they can map it. We still won't know what it is, but at least we'll know where the largest lumps are.

One exciting segment of the final program was where viewers who were taking part in an exercise to find lensing galaxies, which can help to locate far more distant galaxies, came up with a really interesting hit. So much so that they immediately retargeted the Jodrell Bank and several other telescopes around the world at it. We wait the results with bated breath, including the name - which is currently open to suggestions.

But it's when they start talking about how you are seeing distant galaxies as they were several million, or even several billion, years ago that it gets a bit uncomfortable. Especially how the limit to our discoveries is stuff that is 14 billion light years away or closer, because the light coming from anything further away hasn't had time to reach us yet. Even though it all started in the same place at the Big Bang. And galaxies that are near the limit are actually 40 billion light years away now because they kept going since they emitted the light that we are looking at now. So will we still be able to see them next year?

Also interesting was the discussion of what happens when two galaxies collide. It seems that the Andromeda galaxy, our nearest neighbor, is heading towards us at a fairly brisk pace right now. Due to the vast distances between the stars in each galaxy, there's only a small chance of two stars (or the planets that orbit them) colliding, but they say it will produce some exciting opportunities for astronomical observation as it passes through. And there's a theory that the shape and content of own Milky Way galaxy is actually the result of a previous encounter with Andromeda anyway.

For me, however, one of the presenters managed to top all of these facts and theories almost by accident. When asked what the oldest visible thing in the Universe is, he simply pointed to himself and said that all the hydrogen atoms that make up parts of all of us (and everything around us) were made within two minutes of the Big Bang. So pretty much all of them are 14 billion years old.

Of course, the other things that make up us, the larger and more complicated atoms, are a bit younger. Many of these types of atoms are still being manufactured in distant super-novae, but this stuff inside us has no doubt been around for a very long time. As any good astronomer will tell you, Joni Mitchell was right when she sang "We are stardust"...

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We Are Stardust