Showing all posts tagged: astronomy
25 September 2023
Noctalgia is the recently minted neologism for the phenomenon of missing dark skies at night. Noctalgia is something astronomers could tell you about. Dark, light pollution free, skies are essential for their work, but they’re not so commonplace anymore. And here we have a dilemma.
The source of this light pollution is the night lighting that keeps us safe and secure. But light pollution does not only originate from the surface of the planet. The growing number of satellites in Earth orbit, of which we likewise greatly depend, is also adding to the problem for astronomers:
More recently, the explosive growth in satellite communication “constellations,” like SpaceX’s Starlink system, has put orders of magnitude more satellites into orbit than even a decade ago, with even more on the way. Those satellites don’t just spoil deep-space astronomical observations when they cross a telescope’s field of view; they also scatter and reflect sunlight from their solar arrays. The abundance of satellites is causing the overall brightness of the sky to increase all around the globe.
Maybe noctalgia can be added to the list of contender words when dictionaries next update their lexicons, if that hasn’t already happened.
20 September 2023
Astronomers are convinced the solar system hosts another planet, often dubbed Planet Nine, or Planet X, but are unable to agree on its size and mass, nor its location.
A few years ago speculation was rife a Neptune size body was orbiting the Sun well beyond Pluto, taking between ten to twenty thousand years to make a circuit. While mathematical evidence suggested the existence of the planet, observations turned up nothing.
Now astronomers think a planet similar in size to Earth may be lurking in the far reaches of the solar system, though nowhere as far out as the supposed Neptune size body:
According to planetary scientists Patryk Sofia Lykawka of Kindai University in Japan and Takashi Ito of the National Astronomical Observatory of Japan, this world, frozen and dark so far from the Sun, would be no greater than 3 times the mass of Earth, and no farther than 500 astronomical units from the Sun.
29 July 2023
The best way to understand the universe — to whatever extent that is possible — may be to see the cosmos as an animal. A fascinating, yet somewhat unpredictable animal, says Andrew Pontzen, a professor of cosmology at University College London, writing for The Guardian:
It once seemed that, for all its immensity, the cosmos could be understood through the application of a small number of rigid physical laws. Newton encapsulated this idea, showing how apples falling from trees and planetary orbits around our sun arise from the same force, gravity.
J. B. S. Haldane, a Scottish mathematical biologist, said it best, in an essay he wrote almost one-hundred years ago, in 1927, titled Possible Worlds: “Now, my own suspicion is that the universe is not only queerer than we suppose, but queerer than we can suppose.” Words of wisdom, them.
29 June 2023
Scientists think low-frequency gravitational waves generated by super-massive black holes found at the centres of some galaxies may be sending ripples through the fabric of space-time. While astronomers still aren’t one-hundred percent sure these waves exist, they would help in the study of super-massive black holes, if they did.
The super-massive black hole, Sagittarius A — also known as Sag A — at the centre of our galaxy, the Milky Way, may not be a generator of these gravitational waves though. At a mere four point three million times the mass of the Sun, it’s considered to be a relatively small, er, super-massive black hole.
13 June 2023
Quasars, are the single most powerful objects in existence, and are the subject of the latest video from Kurzgesagt. Thankfully, the nearest known such object is about six-hundred million light years away from Earth.
As small as a grain of sand compared to the Amazon River, they reside in the centres of some galaxies, shining with the power of a trillion stars, blasting out huge jets of matter, completely reshaping the cosmos around them.
12 April 2023
The latest feature from Kurzgesagt, those veritable video virtuosos of educational storytelling, explores the possibility of Earth being invaded by an advanced extra-terrestrial civilisation. While Kurzgesagt stresses much of what they present here is speculative, some of the points they raise are nonetheless fascinating.
While this video is based on scientific papers, we are presenting interesting ideas based on little data and lots of extrapolation, so take them with a grain of salt.
Kurzgesagt make the seemingly incredible suggestion that our galaxy, the Milky Way, may one day not be big enough to accommodate all the space faring civilisations that could potentially arise. The notion seems astonishing given the amount of space we’re talking about.
It would take one hundred thousand years to travel from end of the galaxy to the other, assuming we could do so at the speed of light — or who knows, less — if we could travel faster than the speed of light. Still, we’re talking about great volumes of space.
It is also possible humanity is the first technological civilisation to emerge in the Milky Way. This call is made on the basis that there is next to no evidence of the existence of other intelligent lifeforms in the galaxy. This thought is backed up by the Fermi paradox, which asks, if the galaxy is teeming with habitable planets, were are all the extra-terrestrials?
Sufficiently advanced extra-terrestrials would be relatively easy to detect, with the technologies we possess. Their Dyson swarms, their presence in numerous neighbouring star systems, would create blips on the radar, so to speak. That’s not to say there are no other technological civilisations in the galaxy, but if there were, they’re possibly at a similar level of development to ours at the moment.
But intelligent civilisations need significant amounts of time to evolve. The process has taken billions of years on Earth. So while the galaxy seems devoid of space faring civilisations at present, that may change in the next billion or so years, as currently in utero lifeforms grow. Intelligent civilisations also need a stable environment in which to germinate, which Earth, and the Sun, has given us, but some good fortune has been involved in our case.
Kurzgesagt suggests suitably located planets orbiting red dwarf, or M-type stars, which are abundant, provide an ideal environment for intelligent life to develop.
Most stars are red dwarfs that can sustain habitable planets for tens of trillions of years! Life on these planets has an incredibly long time window to appear and pass the hard steps.
Red dwarf stars live for trillions of years, as opposed to billions, for G-type stars such as the Sun. Intelligent life would therefore have more chance of taking hold, as it has plenty of time to do so. On Earth, intelligent life took five billion years to emerge, being half way through the Sun’s approximately ten-billion year lifespan.
But if the process had started any later, it may well have been too late. As the Sun ages, it is becoming warmer, and eventually Earth will be too hot to support life. Humanity, it seems, came along at the right moment. Seen in that context, planets hosted by red dwarfs appear to be the perfect incubator for intelligent life. But things are not that simple: red dwarfs pose their own problems for the emergence of life.
For one, any planets in a red dwarf’s habitable zone, a place where the environment is neither too hot nor too cold, would be tidally locked. This means one side of a planet would permanently face the star, and be exceedingly warm as a result. The other side, meanwhile, would always be shrouded in darkness, and likely too cold for life to thrive.
It has been suggested life could flourish on the day-night terminators of such planets, but this would make for an all too narrow habitable corridor. In addition, red dwarfs also emit radiation flares, which can have the effect of “sterilising” planets in their vicinity, rendering them uninhabitable. That’s not too good. Nor is it conducive for the prevalence of intelligent life.
Given life only spawns in what seems like an extremely slender set of circumstances, an extra-terrestrial invasion may be the one thing we don’t have to worry about. There’s simply no one else out there. Given humanity appears to ascendant then, we have the opportunity, as Kurzgesagt suggests, to carve out our own niche in the galaxy.
14 February 2023
Image courtesy of Evgeni Tcherkasski.
“Aboriginal and Torres Strait Islander people are the oldest scientists in human history.”
Learning this may come as a surprise to readers of Astronomy, Sky Country, written by Karlie Alinta Noon and Krystal De Napoli, and published by Thames & Hudson, winner of the People’s Choice Award in the 2023 Victorian Premier’s Literary Awards.
Because, for instance, were not the Assyro-Babylonians, in Mesopotamia, in south west Asia, documenting their scientific and astronomical research, over three thousand years ago? They were, but Indigenous peoples living in Australia had been making, and recording, astronomical observations tens of thousands of year earlier.
Unlike the Assyro-Babylonians though, who inscribed their knowledge onto tablets and the walls of temples, First Nations Australians recorded information, including astronomical knowledge, differently. Knowledge and stories was passed from generation to generation through word of mouth, cultural rituals, and Songlines.
Songlines were memorised descriptions of pathways or tracks used by Indigenous Australians to guide them from one place to another across country, and included instructions on how to travel, and landmarks to guide their journey. Songlines also contained protocols to observe when crossing other Indigenous peoples’ lands, or country.
But far longer journeys, to destinations a great distance from country, and, on occasions, beyond the Australian continent, required different means of navigation. This is where Indigenous Australians looked to the sky and the stars. This meant travelling overnight when the stars were visible, and when it was also a little more comfortable than trekking through the heat of day.
Torres Strait Islanders, for instance, navigated by a large constellation named Tagai, one of the creator beings. The Tagai group of stars embodies the constellations of Scorpius, the Southern Cross, and Corvus. These three star groups can be seen in the lower left hand quadrant of this constellation map at Nature Noon.
But Tagai was not solely a navigation guide, the constellation also played a role as a timekeeper. Tagai’s movement across the sky as the year progressed, marked the passing of seasons, and acted as a calendar of sorts, indicating times to hunt for food, or harvest crops.
Planets also assisted some Indigenous Australians with navigation, including Venus. Venus was also a part of some Songlines containing cultural lessons and protocols.
Through Astronomy, Sky Country, Karlie Noon, a Gamilaraay astronomer and science communicator, and Krystal De Napoli, a Kamilaroi astrophysicist and educator, bring, through the lens of the cultures of Indigenous Australians, a new understanding to the science of astronomy.
Contemporary astronomical knowledge, for its importance, value, and indeed fascination, is analytical and systematic. Scientists and astronomers of recent centuries have been more concerned with comprehending, and classifying stars as mere stellar objects. Red giant star or red dwarf? What distance are they from Earth, and each other?
But stars are not mere points of light in the night sky. They are also entities that guide, teach, and tell stories. While Indigenous Australians are not the only early cultures to embed legends, stories, and knowledge, in the planets, stars, and constellations, they are among the first.
3 February 2023
Now if Australia had a poet laureate, which it will by 2025, perhaps their work would be winging its way through interplanetary space towards Jupiter. Instead, verse composed by American poet laureate Ada Limón, will be engraved on Europa Clipper, a NASA space probe scheduled for launch in October 2024, to study Europa, one of the giant planet’s largest moons.
The spacecraft is set to launch from NASA’s Kennedy Space Center in October 2024 and by 2030, it will be in orbit around the gas giant. It will conduct multiple flybys of Jupiter’s icy moon Europa, to gather detailed measurements and determine if the moon has conditions suitable for life. Europa is thought to contain a massive internal ocean and is considered one of the most promising habitable environments in our solar system, beyond Earth.
18 December 2022
They were larger — far larger — than any star known to be present in the universe today, and were capable of outshining entire galaxies. And, as the name suggests, they were part black hole. We know some stars become black holes at the end of their lives, but for the two to somehow co-exist, star and black hole, without one destroying the other? How can such a thing even happen?
In 1927, British-Indian scientist J. B. S. Haldane, in an essay titled Possible Worlds wrote the oft quoted sentence: “now, my own suspicion is that the universe is not only queerer than we suppose, but queerer than we can suppose.” It was Haldane’s way of saying we’re unlikely to ever make sense of the universe, no matter how much we learn about it. Black hole stars, in their bizarre weirdness, only add to the wonder.
11 December 2022
It may be possible to construct deep space vessels capable of (eventually) reaching speeds equal to two percent of the speed of light:
Scientists have proposed a dazzling new mission to travel to the stars that is inspired by the elegant flights of seabirds, such as albatrosses, reports a new study. The interstellar concept mission would harness shifting winds generated by the Sun in order to accelerate a spacecraft to as much as 2 percent the speed of light within two years, allowing it to soar into the vast expanse beyond our solar system.
But two percent the speed of light, a velocity that would take some time to attain anyway, isn’t all that speedy considering the vast distances between celestial objects, such as the Sun, and the nearest star to us, Proxima Centauri.
If we round off the speed of light at 300,000 kilometres (km) per second, two percent of that is six thousand km per second. That’s 360,000 km per minute, and 21,600,000 km per hour. 518,400,000 km per day. If my maths is on spec — not always guaranteed — the journey to Proxima Centauri, some 40,208,000,000,000 km distant, would take 77,561 days, or about 213 years.
On the other hand, if Pluto is an average of 5,300,000,000 km from Earth — sometimes it is closer, sometimes more distant — it would take about ten days to travel there. Assuming such speeds could be attained at relatively close proximity to the Sun, that is. This method of deep space travel seems reasonable for reaching points in and near the solar system, but might be out of the question for interstellar voyages carrying people.