Showing all posts tagged: astronomy
Astronomy Picture of the Day website turns thirty
19 June 2025
Administered by NASA, the Astronomy Picture of the Day (APOD) website started posting images in June 1995. This is a time, that in 2025, feels positively prehistoric, when it comes to the web.
I’ve been looking at APOD on and off for maybe twenty years, and as far as I recall, the website has barely changed during that time. I don’t know for sure, but I suspect APOD has sported the same “Web 1.0” design since debuting thirty years ago. While the interface may not be much to look at, that’s not what we go there for: we’re there for the stunningly awesome images.
You can’t follow APOD on any socials channel, but you can subscribe to their RSS feed.
RELATED CONTENT
astronomy, history, photography, science
Milky Way might not collide with Andromeda, Milkomeda might not form
4 June 2025
Some recently revised calculations, based on some more recent data, have shown our galaxy, the Milky Way, may not collide, or if you prefer merge, with Andromeda, a large galaxy presently about two and a half million light years away.
Astronomers have long believed a merger/collision to be inevitable. Although heading towards to each other — at an eye watering speed of about one-hundred kilometres per second — there’s close to a fifty-fifty chance both galaxies will simply sail passed each other.
Milkomeda, the name given to the would-be merged entity, and something I’ve written a bit about in the past, may never come to pass after all. But then again it might, no one can be one-hundred percent sure. Uncertainty is the only certainty.
If you’re stilling gunning for the formation of Milkomeda though, here’s an animation of the what the collision might look like, from the perspective of a far distant observer. Events play out over ten billion years, but are compressed to a minute, meaning things won’t be quite as violent as they look.
Even if Earth were still around at this point — which seems unlikely in five billion years time — the merger/collision of the two galaxies would probably make little difference to anyone still here. Aside from an upheaval in the way the night sky looks, that is.
Despite appearances, galaxies are mainly made up of empty space, meaning the chances of a star from Andromeda barging into the solar system would be pretty remote.
RELATED CONTENT
astronomy, milkomeda, physics, science
The estimated lifespan of the universe has been reduced, adjust your calendars
22 May 2025
The cosmos may not last quite as long was previously envisaged. New calculations have shown that the final stellar remnants in the universe will cease to be in 1078 years time, rather than the originally thought 101100 years. That’s a significant shift in the timeline, however you look at it.
The stellar remnants part of that sentence seems to be key here though. I think. The last star in the universe — which probably won’t even be born for an eternity — will cease shining at some point in the long distant future, but its remains will take 1078 years to turn into near nothingness.
Then, I think, it’ll be curtains for the universe. But what even is 1078? I’m awful at maths and have no idea, but, according to the Thinkster Learning website, 1078 is a one followed by rather a lot of zeros. It looks like a really long time to me.
If there’s something you were hoping to achieve though, it seems like it might be a good idea to get on with it. There’s nothing more motivating than a tight deadline…
RELATED CONTENT
If there is life on K2-18b the K2-18 red dwarf star will kill it off
25 April 2025
News that traces of chemicals possibly indicating the presence of life on a planet, known as K2-18b, some one-hundred-and-twenty-four light years from Earth, resulted in a flurry of headlines the other week. Scientists find strongest evidence yet of life on an alien planet. Scientists claim they’ve discovered most promising ‘hints’ of potential for life on distant planet. And: Scientists Find Promising Indication of Extraterrestrial Life — 124 Light-Years Away.
Sure, it’s exciting. This is news many of us have been waiting for. Even if it’s not quite the definitive announcement we would have preferred. The problem though is the media outlets writing about the discovery of chemical “fingerprints” in the atmosphere of K2-18b, have not looked at the whole story. In fact, it seems they’ve only looked at the first few words. After all, why allow the full facts of the matter to get in the way of a click-bait worthy headline? The biggest — literally — part of the story is K2-18, the star the would-be life-hosting planet K2-18b is orbiting.
I’ve written about this before, but let’s revisit the subject, since it’s topical.
K2-18 is a red dwarf star. Red dwarfs — as the name suggests — are small. Some might only be a little bigger than Jupiter, the largest planet in the solar system. Red dwarfs are dimmer and cooler compared to a star like the Sun. They however have long lifespans, typically measured in trillions of years, rather than billions, as is the case for many other stars in the universe. At first glance, red dwarfs seem like ideal stars to host planets that might give rise to life. Their longevity gives lifeforms an eon to take hold and develop. But red dwarfs are not really life-friendly stars.
One problem lies in their size. Being so small, the habitable, or Goldilocks zone, the area of their solar system best suited for the fostering of life, that is neither too hot, nor too cool, is quite close to the star. Any planets in the habitable zone will be tidally locked. This means one side of the planet permanently faces the star, while the other is perpetually shrouded in darkness. In other words, the star facing side of a planet will be incredibly warm, while the dark side will be quite cold. Neither extreme may be particularly conducive to life, especially complex lifeforms.
But that’s not the worst of it. Red dwarfs also emit powerful flares that can render nearby planets lifeless. Some of these outbursts can be even more intense than those generated by the Sun. While one study of these flares found they might emanate from the polar regions of red dwarfs, rather than their equators, being the plane planets usually orbit a star along, the odds remain stacked against life here. None of this information is new, but has just about been completely overlooked in the recent news stories, about the possibility of life on K2-18b.
Here may be an unfortunate instance of a star that brings life into being, only to take it away later.
RELATED CONTENT
astronomy, current affairs, science
Australia is bigger than Pluto, are then dwarf continents a thing?
22 April 2025
This, an image comparing Australia with dwarf planet Pluto, was published years ago, but somehow I only saw it for the first time a few days ago. Incredible, isn’t it? Width-ways, going from the east to west coasts, Australia dwarfs Pluto (no pun intended).
But drawing comparisons between dwarf planet Pluto, and the Australian continent, however, makes me nervous. Might such a stark juxtaposition result in Australia being downgraded to dwarf continent standing? In the same way Pluto was demoted from full, to dwarf planet, status in 2006?
Were such a travesty to occur, Australia would have to claim the title of the world’s largest island, an honour presently bestowed upon Greenland. That’s not a new idea though, a rum brand, for one, made the suggestion several decades ago.
RELATED CONTENT
astronomy, Australia, geography, humour, Pluto
Does the universe reside within a black hole?
17 March 2025
Good morning, welcome to the new week, and mind-blown Monday. Today we’re discussing life, the universe, the rotation of galaxies, black holes, and everything.
Data collected by the James Webb Space Telescope (JWST) has concluded about two-thirds of galaxies in the universe rotate in one direction, while the remaining third rotate the opposite way. In a supposedly normal course of events, the balance would be more even. Apparently.
But there is any such thing as normal in the cosmos? You know what they say. Truth is stranger than fiction. The universe is not only stranger than we can imagine, it is stranger than we can imagine. Two-thirds of galaxies might spin in one direction, because, you know, just because.
But there’s no just because in this universe. The imbalance in the rotational direction of the galaxies suggests to some astronomers that the universe was born inside a black hole. Since the black hole hosting our universe rotates in one direction, it follows that the majority of galaxies will spin in the same direction. Nikodem Poplawski, a theoretical physicist at the University of New Haven, describes this as the “simplest explanation” of the phenomenon:
“I think that the simplest explanation of the rotating universe is the universe was born in a rotating black hole. Spacetime torsion provides the most natural mechanism that avoids a singularity in a black hole and instead creates a new, closed universe,” Poplawski continued. “A preferred axis in our universe, inherited by the axis of rotation of its parent black hole, might have influenced the rotation dynamics of galaxies, creating the observed clockwise-counterclockwise asymmetry.”
I wonder how far up and down the “levels” of universes residing inside black holes goes then? If our universe is indeed located within a black hole, it follows that other universes must reside within the plentiful black holes that populate our universe. And inside those universes will be yet more black holes, that will be home to further universes. And so on.
But where does our black hole universe sit in such a hierarchy? Near the top? In the middle somewhere. Or near the bottom? If such a thing exists, as there may be no limit to how how far down the progression can go. The same applies going up the other way of course, in theory.
It’s mind blowing stuff for sure. If, that is, you accept this two-thirds versus one-thirds split of galaxy rotation represents a significant imbalance in the first place. There might still be room for just because here. After all, weird things just happen in this wondrous universe of ours.
RELATED CONTENT
No planet has two hundred and seventy plus moons, not even Saturn
15 March 2025
Saturn’s moon count leapt a few days ago, after the International Astronomical Union (IAU) decided to classify an additional one-hundred-and-twenty-eight objects orbiting the ringed planet, as moons. It must be quite the feat of achievement for Saturn to boast it has the most number of satellites, by far, of any other planet in the solar system.
These new moons now mean Saturn is possessed of two-hundred-and-seventy-four satellites. But let’s be serious here. No planet has that many moons, real moons. All of Saturn’s new “moons” are just tiny rocks. They count as moons though, because they have a “proven orbit” around Saturn:
Most of the moons are irregular and tiny, just a few miles across. By comparison, our moon has a diameter of 2,159 miles (3,475 kilometers). But they do have proven orbits around Saturn, which is a key element of official moon candidacy.
Former planet Pluto has a proven orbit around the Sun, yet it is now considered a dwarf planet. This because it no longer meets the IAU’s definition of a planet. We can have different types of planets, it seems, but a moon is always a moon, even it is pet rock size.
But if planetary bodies need to fulfil a certain criteria to be deemed a (real) planet, then a tighter classification of what constitutes a moon, a real moon, is long overdue. If we use our moon, the Moon, as a benchmark, then perhaps Saturn has half a dozen or so “real” moons. The rest would be, as I wrote of Mars’ so-called moons in 2014, merely captured objects.
ETA: on the subject of Saturn, the planet’s fabulous rings will seem to disappear later this month, as far as observers on Earth are concerned. This is because the rings will be edge-on to us, a phenomenon called ring plane crossing, something that happens about every fifteen years.
The rings will become become visible again later in the year though. Who knows, without the rings to distract astronomers on Earth, maybe another batch of moons will be found orbiting Saturn.
RELATED CONTENT
Sending people to Mars will be challenging, for all the wrong reasons
25 February 2025
Maciej Cegłowski’s in depth (deep dive) articles on an array of topics are always worthy reading, even if I’m not always able to consume his pieces in one go. In his latest long form column, he takes on the prospect of sending an Apollo-like flight to Mars, complete with a human crew on board. But going to Mars is not even remotely like a jaunt to the Moon:
A trip to Mars will be commital in a way that has no precedent in human space flight. The moon landings were designed so that any moment the crew could hit the red button and return expeditiously to Earth; engineers spent the brief windows of time when an abort was infeasible chain smoking and chewing on their slide rules.
But within a few days of launch, a Mars-bound crew will have committed to spending years in space with no hope of resupply or rescue. If something goes wrong, the only alternative to completing the mission will be to divert into a long, looping orbit that gets the spacecraft home about two years after departure.
Sending people to Mars is not beyond the realm of possibility, but it will be difficult, incredibly difficult.
RELATED CONTENT
A supermassive black hole is set to collide with the Milky Way
21 February 2025
It’s true: a supermassive black hole is on a collision course with our galaxy. But the happening is at least two billion years away.
And even then it may not be a black hole, but rather a “massive invisible object” thought to lurk within the Large Magellanic Cloud (LMC), a smaller galaxy that presently orbits the Milky Way, but which is slowly falling towards us. Once the LMC collides — though merge is probably a more apt word — with the Milky Way, the black hole, or whatever the invisible body that the LMC hosts, will make a bee-line for Sagittarius A*, the supermassive black hole at the centre of our galaxy.
When those two objects eventually collide — an event that will unfold at a likewise cosmologically glacial pace — the result will be the formation of an even more monstrous black hole.
While the black hole merger process may be drawn out, assuming a black hole indeed resides inside the LMC, it will no doubt be a bumpy ride for whatever interstellar objects lie in the path of the two, as they fuse together. Perhaps the solar system will find itself in harm’s way here. The only consolation there is it’s something we won’t be around to see.
RELATED CONTENT
Gravastars and black holes, a weird cosmic double act
2 January 2025
The concept of gravastars (or gravitational vacuum stars) is a fascinating alternative to the idea of black holes, although if their presence were ever proved, they would not rule out the existence of black holes. Proposed by Pawel O. Mazur and Emil Mottola some twenty years ago, these objects are consistent with Albert Einstein’s general theory of relativity.
Gravastars, like black holes, form in the aftermath of some supernova explosions. They are relatively small, their size might be similar to London, capital of the United Kingdom.
In terms of appearance they are black, and a little like balloons, having an extremely thin shell, consisting of matter scientists do not yet understand. Their interior is filled with a vacuum, or dark energy, bustling to break out, but unable to do so. Gravastars sound like an incredible phenomena, but in a universe some think is devoid of dark energy, I wonder if they could actually be present.
RELATED CONTENT