Category: The Cosmos

Space Snooker

11/14/2022

309 words: 3-minute read

Can I be the only one who wishes that our exercise in ‘space snooker’ had been a little less successful? The thought there is now a ten-thousand-kilometre-long dust cloud trailing behind asteroid Dimorphos where there wasn’t one before will delight some for the influence it shows we can have on the universe - and dismay others for the same reason.

Over thirty years ago Bill McKibben alerted us to the ‘end of nature’ in his eponymous book, arguing that global environmental change meant that ‘every inch and hour’ of the globe had the mark of the human on it. From now on, he wrote, a child born today will never know summer - only ‘summer’. With DART we’ve now proved ourselves capable of changing the dynamics of the universe itself, and I couldn’t help thinking as I looked up at the stars the other night that I was observing the ‘universe’, not the universe.

Call me over-sensitive, but we might have learned by now that overindulging the Promethean instinct can lead to less-than-ideal outcomes: climate change, biodiversity loss, the Covid pandemic. DART was an exercise in prophylactic Prometheanism, the side effect of which is to undergird the belief that we can protect ourselves from any eventuality rather than try to avoid it in the first place.

Here on Earth, prophylactic Prometheanism in the face of Covid led to untold numbers of collateral victims, a virtual absence of attention to its causes, and a handing over of emergency powers to the UK government which have - surprise, surprise - found their way into the draconian Police, Crime, Sentencing and Courts Act and the Public Order Bill.

So yes, I rather wish our DART had missed, then Icarus could have a conversation with Prometheus and here on Earth we’d be talking more about prevention and less about cure.

where does gold come from?

7/6/2022

514 words: 4-minute read

I’m sitting here holding my mother’s wedding ring wondering where the gold came from. I don’t mean which country it came from. I mean where did it come from?

Turns out that I’m holding the remnants of a star. A star that was born and died possibly billions of years ago, perhaps billions of light years away.

In fact it turns out that that’s where I come from too - the calcium in my teeth, the iron in my blood and the sodium in the potato I ate for lunch were all formed in dying stars.

It’s astonishing how recently some of the most mind-bending yet taken-for-granted discoveries were made. For example, around 100 years ago we thought there was only one galaxy - the one we inhabit, which we call the Milky Way. Sure, there were smudges in the sky that were called nebulae, but we thought they were all patches of dust or gas in our galaxy, the Milky Way.

Then in the 1920s, using a technique developed by Henrietta Leavitt, Edwin Hubble worked out that a star he was studying was so far away that it had to be outside our galaxy. In fact it was in what we now know as the Andromeda Galaxy. Anyone in the northern hemisphere with good eyesight can see Andromeda (better with binoculars or a small telescope) - and it’s quite something to think that the photons striking your eye set out on their journey two million years ago.

Suddenly the universe was way bigger than we ever thought it was. Now we know that there are between 100 and 200 billion galaxies in the universe - not just the one we thought until about 100 years ago.

And it wasn’t until even more recently - 1946 - when Fred Hoyle published ‘The Synthesis of the Elements from Hydrogen’ in the Monthly Notices of the Royal Astronomical Society, that we learned how the heavier elements were made.

Here is part of the article’s abstract:

‘Stars that have exhausted their supply of hydrogen in regions where thermonuclear reactions are important enter a collapsing phase. If the mass of the star exceeds Chandrasekhar's limit [i.e. greater than 1.44 times the mass of our sun] collapse will continue until rotational instability occurs. Rotational instability enables the star to throw material off to infinity … The process of rotational instability enables the heavy elements built up in collapsing stars to be distributed in interstellar space’ (emphasis added).

Almost all the elements in the periodic table were created in dying stars. When a star begins to run out of hydrogen towards the end of its life, it expands into a Red Giant (when our sun does this it will swallow up Mercury and Venus). At this point the element carbon is formed. In more massive stars, even heavier elements such as oxygen and iron are created.

The most massive stars end their lives as supernovae, and this is where elements heavier than iron, such as uranium and gold, are formed.

And every atom of gold in the ring I’m holding. Which is billions of years old. In fact I may be holding most of the history of the universe in my hand.

un pedazo de cielo (a patch of sky)

5/16/2021

505 words; 4-minute read

When you’re lucky enough to be able to buy a house, a flat or an apartment there are a few things you’re encouraged think about. Is it structurally sound? What’s the roof like? Plumbing and electrics OK? What’s the area like? And the neighbours? And make sure you go back a few times so you get a feel for the property under different conditions.

What nobody thinks about is the night sky you’re going to have a view of. However many times you revisit a property you’re probably not going to check it out at night-time. If you’ve got a house with a garden or you’re some way up a high rise the odds are you’ll have a fair bit of night sky to look up at and you'll most likely take the view for granted. But if not, then the first time you think about the stars and planets above your flat will be the night after you’ve handed over your money and moved in.

So I’ve struck lucky. It’s mid-May so I can only talk about the stars we’ve got above us in our patch of sky at about 10 in the evening at this time of year. But it could be less interesting. A lot less interesting.

Right overhead is Ursa Major, the Great Bear, with its four stars in a rough rectangle, and three more curving away eastwards. The light pollution of the city stops me from seeing the naked eye double star - Mizar and Alcor - in the middle of the pan handle, but I know it’s there and that’s good enough for me.

Follow the curve and there’s Arcturus, the fourth brightest star in the night sky, a red giant in the last stages of its life. It’s 36.7 light years away which means that the light from it striking our patio last night set off in late 1984 when in the UK the miners’ strike was being broken and British Telecom was privatised. In Spain, Felipe González was in his second year as Prime Minister and Neanderthal bones nearly half a million years old were found in a cave at Atapuerca.

On the other side of our patch of sky, to the west, are the Heavenly Twins (Gemini), Castor and Pollux, and across to the right and a little way down there’s Capella, the sixth brightest star in the sky, 42.9 light years away, and one of the strongest X-ray sources in our galaxy.

And right now there’s an extra treat on view because Mars is visible just below Gemini, an unmistakeable red counterpoint to Arcturus.

All in all not a bad haul for what’s in effect just a sliver of sky above us. If or when we come to sell this apartment I’ll be sure to include the May night sky among its unlikely attractions.

the great conjunction

12/19/2020

411 words - 3 minute read

While the particle a millionth of an inch long whose defences are destroyed by washing our hands in soap and water for 20 seconds, also known as Covid-19, continues to wreak havoc around the world, the cosmos is doing its best to entertain us.

Since the summer I have been watching Jupiter and Saturn closing in on each other in the night sky. Back in England I had a telescope, good enough to see the Jupiter’s four biggest moons (just like Galileo), as well as the rings of Saturn. Even with the telescope, the planets look tinier than my little fingernail - but it’s like the difference between a photo of Van Gogh’s Sunflowers and seeing the original in London’s National Gallery.

So I could see the planets getting closer but I had no idea until a few days ago that they were heading for a Great Conjunction, appearing side-by-side in the night sky. And closer than they’ve been since 1623 when Shakesepeare’s First Folio was being published.

Now I’m in Valencia, Spain, without a telescope, but with pretty much guaranteed clear skies every night. Saturn is bearing down on Jupiter, or so it seems on the two-dimensional canvas that’s the night sky. Last night they were half a fingernail’s width apart, and at 19.37 on the 21st December they’ll be indistinguishable with the naked eye. Yet looked at ‘from the side’ they’ll be about 650m kms distant from one another. Then they’ll begin drifting apart and won’t be so close again until 2080. For me this is very much a one-off event.

The 21st December is also the Winter Solstice, so some eight hours before the Great Conjunction the earth’s northern hemisphere will begin to tilt back towards the sun and the days will get longer. And the universe turns another notch, insensible to our trials and tribulations.

So here are we humans, stuck somewhere between a tiny particle that threatens to undo us in the short term and the motion of the quantic universe leading inexorably to heat death. The cosmos doesn’t much mind what happens to us. But on the other hand we may be the only beings in the universe capable of that thought, so we should take care of ourselves and all that sustains us.

Notes from a cliff-edge

Space Snooker

where does gold come from?

un pedazo de cielo (a patch of sky)

the great conjunction

Andrew Dobson

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