Showing all posts tagged: astronomy
15 June 2022
Dyson spheres are hypothetical mega-structures highly advanced planetary civilisations might construct around their host star to harness as much solar energy as possible to power their needs. Seen from a distance, a Dyson sphere would look like a massive shell almost completely encompassing a star.
It’d be like constructing a giant display case for the Sun. Needless to say building a Dyson sphere is no small undertaking, and would require an enormous quantity of resources, technological smarts, plus an unprecedented level of international cooperation. A single superpower could not take on an engineering feat of this scale alone, it’d be a team effort.
Dyson spheres have been in the news relatively recently. Fluctuations in the light of Tabby’s Star, located about 1,470 light-years from Earth, were puzzling astronomers, and the existence of a Dyson sphere was advanced as a possible explanation, though later ruled out.
While Dyson spheres, something late British American mathematician and physicist Freeman Dyson first wrote about in 1960, are unlikely to feature in our future anytime soon, the concept may help us combat global warming.
A team of MIT scientists have devised a solar filter of sorts, they call space bubbles. In short, a small structure made up of numerous of these space bubbles could be used to form a shield, deflecting a small, though sufficient amount of solar radiation away from the Earth.
The MIT scientists propose placing the space bubbles at the Lagrange point between the Earth and the Sun. Put simply, a Legrange point, is an area between two celestial objects, say the Earth and the Sun, where the gravity of both objects balance each other. For example if a satellite were placed at this Legrange point, it would stay put, and wouldn’t fall towards either the Earth or Sun.
Once in place, the space bubbles would act like an eclipsing body, in this case permanently blocking, or more like filtering, a small amount of the Sun’s rays reaching the Earth. While the proportion of solar radiation “blocked” would be minuscule, the MIT team say if just under two percent of “incident solar radiation” was deflected, current global warming could be fully reversed.
28 May 2022
When the Hubble Space Telescope was launched in 1990 the universe’s expansion rate was so uncertain that its age might only be 8 billion years or as great as 20 billion years. After 30 years of meticulous work using the Hubble telescope’s extraordinary observing power, numerous teams of astronomers have narrowed the expansion rate to a precision of just over 1%. This can be used to predict that the universe will double in size in 10 billion years.
That’s mind blowing. To say the least. The already enormous cosmos will one day be twice its present size. Too bad no one here today will be around to see it. But what does it matter anyway? Well, you’d be surprised. Given some two point two million new books are published every year, one can only imagine how many more publications there’ll be in ten billion years’ time.
With a much larger universe by then, it’s comforting to know there will be space to put them somewhere…
23 March 2022
From BBC Earth Lab. Many millions of years ago, one of Saturn’s erstwhile moons, strayed a little too close, crossed a line, the Roche Limit, and shattered into billions of pieces, having been torn apart by the immense gravity of the Solar System’s second largest planet.
Saturn’s incredible ring system was the result of this cataclysmic event, once the remnants of the moon, some seventeen trillion tons of icy material, spread out in orbit around the planet. It would have been an incredible spectacle to witness, had anyone been around to see it all happen.
3 March 2022
HR 6819 is a binary star about 1120 light years from Earth. So far so good, binary stars are a dime a dozen in the Milky Way. But one member of the duo — though some astronomers speculate HR 6819 may be a three star system — which is about four times the size of the Sun, is sucking material away from its smaller counterpart. Astronomers have a special name for stars like this: vampire stars.
In binary systems where two stars are close together, it’s not uncommon for one star to “suck” away the atmosphere of the other – a phenomenon sometimes called “stellar vampirism”. The researchers believe they may have observed the immediate aftermath of a stellar vampire attack in HR 6819.
23 December 2021
Comet Leonard is making a once in eighty-thousand year flyby of the Earth, lighting up, in a way, the festive season night sky. A hunt around on Twitter will turn up a mass of fantastic images of the comet, but here are a few of my favourites.
4 June 2012
Several billion years hence our galaxy, the Milky Way, will collide with galactic neighbour Andromeda, and form a new entity some are calling Milkomeda. This NASA image depicts key steps in the process, and if nothing else will transform the night sky into a visual spectacle.
Not that anyone will probably be around to think about it anyway, but the night sky will have far less appeal once the merger is complete. The bright white haze (in the last frame) that will eventually take the place of the Milky Way (first frame) looks a little bland to me.
Via NASA Science.
Originally published Monday 4 June 2012.
12 July 2009
Eventually our galaxy will collide (or, if you prefer, merge) with the Andromeda galaxy forming a new body some are already calling Milkomeda.
But this photo of four galaxies colliding — by the way — at speeds of up to two million miles (or 3.2 million kilometres) an hour, may be indication of what to expect when Milkomeda does form.
Originally published Sunday 12 July 2009
18 February 2009
My recent mentions of the eventual merger/collision of the Milky Way and Andromeda galaxies, giving rise to “Milkomeda”, has prompted some reader questions about the likelihood of a star from Andromeda colliding with the Sun, during the “merger”.
One thing to remember is the collision is billions of years away, should it even happen, but the chances of stars from either galaxy colliding are extremely remote given the astronomical distances between them:
As with all such collisions, it is unlikely that objects such as stars contained within each galaxy will actually collide, as galaxies are in fact very diffuse – the nearest star to the Sun is in fact almost thirty million solar diameters away from the Earth. (If the sun were scaled to the size of an American quarter, 24.26 mm (0.955 in), the next closest quarter/star would be 700 km (475 miles) away.)
Originally published Wednesday 18 February 2009.
11 February 2009
We already know it is likely our galaxy, the Milky Way, will merge (a subtle way of saying collide actually) with our, for now, distant neighbour Andromeda, forming an entity called “Milkomeda”.
It is also possible however that our Solar system will see out its days completely alone somewhere in the cosmos, if it is somehow ejected from the Milky Way during the Andromeda “merger”…
The future is never certain, though, and alternative endings can be written. There is a slim chance that the whole solar system, sun and all, might be thrown out of Milkomeda intact. Out in the emptiness of intergalactic space, the planets would be safe from marauders. There they could continue to circle our darkening star until their energy is eventually sapped and they spiral inwards. One by one as they hit the black-dwarf sun, a few final flares will rage against the dying of the light.
Originally published Wednesday 11 February 2009.
28 January 2009
Our galaxy, the Milky Way, is destined to “merge” with our giant neighbour, Andromeda, in about five billion years.
Currently both galaxies are approaching each other at speeds of 120 kilometres (km) per second, and “Milkomeda” is one name that has been dubbed for the combined entity.
Before the collision occurs though both galaxies will fly past each other twice, occurrences that could possibly result in the Sun, and its family of planets, being drawn into the Andromeda system.
There is also a remote 3% chance that the Sun will jump ship and defect to the Andromeda galaxy during the second close passage. “In the night sky, we would then see the Milky Way from a distance,” says Loeb.
Just to put the distances into some perspective, moving at a rate of 120 km per second means covering about 3.8 billion km per year. The planet Neptune is some 4.46 billion km from the Sun, so we are talking about some very, very, vast amounts of space here.
Originally published Thursday 28 January 2009.
13 January 2009
If search engine queries here are anything to go by, the prospect of Antares, a red giant star located in the constellation of Scorpius, exploding seems to intrigue some visitors, so I decided to learn more about the imminent (anytime in the next million years, that is) Antares supernova.
In a word though, it will be spectacular.
While it will be unmissable in the night sky, the remnants of Antares may – for a short time – be visible during the day, and even alien astronomers in distant galaxies will temporarily see our galaxy, The Milky Way, outshine many other galaxies that are visible to them, as a result of the explosion.
Despite the galactic light-show the explosion of Antares will not however pose any direct danger to Earth.
There are fears that an exploding star, or supernova, could threaten our planet by way of debris from the blast, or that the resulting radiation and gamma rays could destroy Earth’s ozone layer, in turn triggering a mass extinction.
The only possible risk lies in the glare that any supernova could generate, which may be blinding, according to Dr Nick Lomb of the Sydney Observatory.
Antares isn’t the only potential supernova-star in the stellar neighbourhood either, and Eta Carinae, about 8000 light years away from Earth, could also explode at any time.
Originally published Tuesday 13 January 2009.