Hello readers!
Welcome back to Launchpad. One of the most surprising things that writing about astronomy has given me is an appreciation of the very small. The tiniest things in our universe can have a colossal impact. I can’t count how many times a week I write “cloud of dust and gas”, but it’s a whole lot. That’s because, as annoying as it may be when dust obscures our views of the cosmos, its presence is crucial to pretty much everything. |
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What's happening up there |
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Credit: Intuitive Machines |
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Two lunar landers have fallen over – but they’re still doing okay |
The SLIM lander and the Odysseus lander both set down on the lunar surface on their sides, but they have each been able to send data back to Earth. Read more |
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Huge set of galaxies is set to form largest cluster in known universe |
Astronomers have spotted a gargantuan protocluster – the primordial beginnings of a galaxy cluster – by searching near a quasar in the early universe. Read more |
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Tiny new moons have been spotted orbiting Neptune and Uranus |
Astronomers have found a new moon around Uranus and two orbiting Neptune – the first moons discovered orbiting these planets in a decade and the faintest ever spotted. Read more |
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Let’s start at the beginning. For about a hundred million years after the big bang, there were no solids – no dust. First there was just boiling hot plasma, and then as it cooled, only hot gas. The universe went on expanding and that gas began to cool down and clump up, separating into globs like a broken buttercream. Over millions of years, the lumpiness got worse, eventually making pockets so dense that they collapsed in on themselves and began to fuse atoms together. These were the first stars.
They lived their entire lives in a dust-free universe, aside from small amounts that may have formed in their atmospheres. And then they exploded. In the immense heat and pressure of these first supernovae, heavy elements such as carbon and nickel formed – these became the first dust in the universe. And it immediately became important.
While the first stars would have formed on their own from direct collapse, future generations tended to be born in stellar nurseries, which are huge clouds made up of mostly hydrogen and helium. When these collapse, they also heat up, creating radiation that pushes outward and counteracts the inward flow, bringing the clouds to a sort of uneasy equilibrium. That’s no good for star formation. Enter: dust. It also creates radiation from any heat it absorbs, but in this case it comes out in infrared wavelengths that pass right through the gas, instead of pushing back on the matter trying to collapse.
Once the stellar nursery has discharged its baby stars, dust plays an important role yet again: it is the main building block of planets. As young stars rotate, they collect a disc of dust and gas around them, and in a process somewhat similar to the one by which the first stars formed, clumps grow in that disc. These eventually stick together and become larger and larger rocks, and then planets. The composition of the dust in the disc has a powerful influence on the geochemistry of the resulting planets.
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Even then, after helping with the formation of entire planetary systems, the role of cosmic dust isn’t over yet. Skip forward to just before the dawn of life on Earth, around 4 billion years ago. Things were violent in the early solar system, with many asteroids smashing and grinding together, producing more and more space dust. Hundreds of thousands of tonnes of that dust – or maybe even more than that, we don’t know for sure – blanketed the surface of the young Earth every year.
And the thing about cosmic dust is that it isn’t the same as dirt here on Earth. Some of the elements that are crucial to life, such as phosphorus and sulphur, are inaccessible in Earth dust but abundant in cosmic dust. I imagine you can see where I’m going with this. As all that cosmic dust fell on Earth, it would have brought with it ingredients that were crucial to the rise of life. For a long time, the possibility that space dust could have had anything to do with the first life on Earth was dismissed because the dust would have been spread all around the world in a layer too thin for any one location to have enough of those crucial elements to matter.
But thanks to a new study, that’s being rethought a bit. It turns out that in some locations, particularly on glaciers, cosmic dust could have gotten trapped in small pools of water, forming little cups of primordial soup. One of the ways we know this could happen is that such pools still exist in glacial regions today. In fact, they tend to be extremely radioactive because radiation fallout from around the world collects there, just like cosmic dust would have done billions of years ago. With a little burst of energy, such as a serendipitous lightning strike, those dusty pools could potentially have been the sources of the first life on our world.
From stars to planets to life itself, dust is important to it all. You might already be aware of the famous quote from Carl Sagan about star stuff, but I want to leave you with an earlier iteration from astronomer Harlow Shapley: “We are made of the same stuff as the stars, so when we study astronomy we are in a way only investigating our remote ancestry and our place in the universe of star stuff.”
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Credit: NASA/STScI/CfA/P.Challis |
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No, it’s not the Eye of Sauron. It’s actually the famous supernova 1987A, which, as its name suggests, was first spotted in 1987. Astronomers have been tracking its development since then, making it the best-studied supernova ever. Despite that, we haven’t known whether it left behind a black hole or a neutron star at the centre of the debris… until now. New observations with the James Webb Space Telescope have shown that what’s left is a hot neutron star, not a black hole. Read more
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Richard writes: “When we look out into space, we see it as it was in the past, because the speed of light is finite. What if we could see it all as it actually is right now, in our time frame?”
This question brings up a fascinating thing about the nature of perception and time that I never get sick of talking about: there is no such thing as “right now”. In every way that we perceive the world, it takes time to get from objects to us and then from our sensory organs to our brains, so even if I look in a mirror placed right next to my eyeball, I wouldn’t see myself as I am in this exact moment (but I would get eye strain).
But that’s maybe not in the spirit of the question, so let’s say that we learn to control time and let each part of the universe age an amount that’s proportional to its distance from us, so that we see everything at the same age – 13.7 billion years old. The biggest problem there is the expansion of the universe, because that’s happening everywhere and has a major effect on the cosmos. If, as we let the universe age, we also let it expand, the night sky is going to dim just because of the increasing space between everything. Galaxies would be bigger, because they take time to grow, but stars would be smaller because small stars live longer. But you’d need a big telescope to see any significant difference – everything that’s visible to the naked eye would remain as it is. And astronomy would be rather harder, because we wouldn’t be able to look into the past to figure out how the cosmos has evolved.
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Exomoons, moons around planets that orbit other stars, offer an exciting prospect to search for alien life. As some of Jupiter and Saturn's natural satellites show, moons can have habitable conditions much further from a star than planets can. But finding exomoons has always been a nearly impossible task. New techniques like spotting rogue planets that drift alone in the universe, along with the capabilities of telescopes like JWST, have brought exomoon hunters within reach of a discovery. If only they could get time to use the telescope. Read more
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Thank you for reading! If you have any comments, questions or wild hypotheticals about space, let me know by emailing me at launchpad@newscientist.com and I’ll try to answer them in an upcoming newsletter.
And remember… the average US home collects about 18 kilograms of dust each year. So it would take 2 million households to produce even the upper limit on theamount of cosmic dust that hit Earth in a single year. That’s less than two-thirds the amount of households in London or New York City. Relatively speaking, it turns out that there isn’t all that much cosmic dust on Earth nowadays… or our houses are really, really dusty, depending on how you look at it. I’m going to go mop.
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.jpg "Artist's representation of a protoplanetary disc")
