Showing all posts about astronomy
Photos of Comet Leonard
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.
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Planets, moons, and stars, made to order by the Little Planet Factory
8 March 2017
Astronomy geeks will love this. 3D printed models of the planets, and moons, of the solar system, made by George Ioannidis of the Little Planet Factory (Internet Archive link). Above is an image of Earth posing with Jupiter, and a sans-rings Saturn.
You can also order the Sun. And the three stars of the Alpha Centauri, and Proxima Centauri system, our nearest neighbours in interstellar space. Or the Moon. Or Mars, when it once had oceans.
Originally published Wednesday 8 March 2017, with subsequent revisions, updates to lapsed URLs, etc.
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art, astronomy, illustration, legacy
NASA finds seven earth size planets, but are they anything like Earth?
24 February 2017
After days of keeping us in suspense about a new discovery, NASA let the cat out of the bag, in the early hours of yesterday morning. The TRAPPIST optic robotic telescope, located in Chile, recently identified a dwarf star, about forty light years distant from Earth, that is host to seven planets around about the same size as Earth.
Come on now, you didn’t think NASA was going to announce that an alien civilisation had been found, did you? This is still a significant discovery though.
Particularly as three of the seven bodies orbiting TRAPPIST-1 — the star also takes its name from the Belgian operated telescope — are within its star system’s so-called Goldilocks, or habitable zone. This is an area around a star capable of supporting life, that is neither too hot, nor too cold.
It is this bit that is especially of interest, as it means these planets may harbour water in liquid form, and, as a result, potentially life of some sort. And that is obviously an exciting prospect. But talk that we may one day be able to emigrate there is well wide of the mark, to say the least.
There’s a big difference between a planet that is earth-like, and one exactly like Earth. Such bodies are called an Earth twin, or Earth analog. For example, Proxima b, an exoplanet within the habitable zone around Proxima Centauri, the nearest star to the Sun, is considered to be earth-like, as it is a rocky, or terrestrial planet.
It might have some sort of atmosphere, and possibly there could be liquid water on its surface. But Proxima b may be far from habitable, at least as far as humans are concerned. As Proxima Centauri is a red dwarf star, which are relatively cool, Proxima b would need to be quite close to the star, to be within the habitable zone.
With that sort of proximity however, Proxima b would be tidally locked, meaning the planet’s rotational period matches the time it takes to orbit the star. The result here is only one side of the planet would ever face the star.
Therefore, the day side of Proxima b would be quite warm, whereas the night side would be extremely cold. The only spots that might be conducive to life, would be near the day-night terminator. Red dwarf stars themselves pose problems for any planets they host. For instance, they are prone to emitting powerful flares, which may have the effect of sterilising nearby planets.
Not so earth-like, after all. So while some form of life may manage to eke out an existence there, the environment would hardly be suitable for human occupation. The same conditions could well apply to the planets within the Goldilocks zone of TRAPPIST-1, given it too is a relatively cool dwarf star.
I think we might be waiting a long time indeed for news that a planet as habitable as Earth is found. In the meantime we should give thought to taking greater care of our own Earth. Clearly we’re not going to be rocketing off anywhere else in any hurry.
Originally published Friday 24 February 2017, with subsequent revisions, updates to lapsed URLs, etc.
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astronomy, legacy, red dwarf, science
Life on Earth is premature: that is why we are alone in the cosmos
4 August 2016
Since the Fermi Paradox intrigues me. Life on Earth is premature. A fluke perhaps. The universe is still relatively young, that’s why we haven’t detected signs of intelligent life elsewhere.
If we compare the present age of the universe, against its projected lifespan, possibly twenty trillion years, then it has an age comparable to an eighteen day old child, who would be expected to live for seventy years. Eighteen days. That’s pretty young.
The cosmos isn’t yet mature enough to be teeming with life.
The dominant factor proved to be the lifetimes of stars. The higher a star’s mass, the shorter its lifetime. Stars larger than about three times the sun’s mass will expire before life has a chance to evolve. Conversely, the smallest stars weigh less than 10 percent as much as the Sun. They will glow for 10 trillion years, giving life ample time to emerge on any planets they host. As a result, the probability of life grows over time. In fact, chances of life are 1000 times higher in the distant future than now.
Originally published Thursday 4 August 2016, with subsequent revisions, updates to lapsed URLs, etc.
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astronomy, legacy, physics, science
Planet Nine, a captured exoplanet? How B-grade sci-fi is that idea?
6 May 2016
There has been chatter in recent months about Planet Nine, a would-be planetary body lurking on the extreme far reaches of the solar system.
The hypothetical planet is so far away, its orbital period around the Sun is estimated at ten thousand years. By comparison, Pluto, the solar system’s best known dwarf, and outermost planet, completes a lap around the Sun in about two-hundred-and-forty-eight years.
But back to Planet Nine. Before even confirming the body even exists, astronomers are trying to figure out its origins. Wouldn’t that be easier once the planet is found? Whatever, some scientists believe it formed relatively close to the Sun, before being dispatched to the solar system’s outer reaches after a run-in with Jupiter.
Others, however, think Planet Nine is an exoplanet, a once rogue exoplanet possibly, that was captured by the Sun, after straying a little too closely to our solar system.
The final scenario sounds like a plot line from a B-grade sci-fi movie, and it seems to be comparably unlikely. Planet Nine could be an extraterrestrial invader. “Planet 9 may be an exoplanet in our own solar system,” said Gongjie Li, another astronomer at Harvard’s Center for Astrophysics whose recent modelling paper explores this very possibility, among others.
I’m not sure though I like the notion of Planet Nine being described as “a plot line from a B-grade sci-fi movie”, since it’s an idea I’ve been kicking around, as if it were a cosmic soccer ball, so to speak, in one of my sci-fi writing projects.
Originally published Friday 6 May 2016. Updated Friday 24 May 2024.
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Pluto, the solar system’s other red… planet?
14 July 2015
NASA’s New Horizons space probe will probably be skimming, mere thousands of kilometres, passed Pluto around about now. That means the photos it sends in the next few days will doubtless be far sharper than the above image of Pluto and Charon, taken from a distance of approximately twenty million kilometres.
While it’s been known for sometime Pluto is reddish-brown in colour, I didn’t realise it was referred to as the solar system’s “other red planet”, with Mars being, I guess, the red planet. While both have reddish hues, their colouring comes about in quite different ways:
What color is Pluto? The answer, revealed in the first maps made from New Horizons data, turns out to be shades of reddish brown. Although this is reminiscent of Mars, the cause is almost certainly very different. On Mars the coloring agent is iron oxide, commonly known as rust. On the dwarf planet Pluto, the reddish color is likely caused by hydrocarbon molecules that are formed when cosmic rays and solar ultraviolet light interact with methane in Pluto’s atmosphere and on its surface.
Also, isn’t referring to Pluto as “other red planet”, with the operative word being planet, likely to start all sorts of arguments?
Originally published Tuesday 14 July 2015.
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astronomy, legacy, Pluto, science
Planet X? No, that idea can be crossed off the list then
18 March 2014
For a long time astronomers believed, or hoped, there was a Jupiter, or Saturn, size planet lurking out in the distant reaches of the solar system. The presence of such a body, commonly referred to as “Planet X”, they thought, might account for the odd orbital paths of some of the other outer planets, dwarf planets, and various other Trans-Neptunian Objects (TNO).
But no, a NASA backed mission, that has spent just over a year scanning the sky, did not find any evidence of a such planet:
This news comes from a paper analyzing observations by WISE, the Wide-field Infrared Survey Explorer, a scrappy little mission that spent 13 months mapping the entire sky in infrared wavelengths. This is where warm objects are bright, things like dinky stars, asteroids, galactic dust, and more. WISE was very sensitive and was able to see objects that were pretty faint. For example, it found tens of thousands of previously undiscovered asteroids, some of which get pretty near the Earth. These glow in the infrared, heated by the Sun. What it didn’t discover, though, was another giant planet in our solar system. And it’s pretty definitive: It would’ve seen a planet the size of Saturn out to a distance of 1.5 trillion kilometers, more than a tenth of a light year! A planet the size of Jupiter would’ve been seen out to twice that far.
I imagine it’s possible there are other, much smaller planets, or dwarf planets, yet to be detected, out in the solar system’s far reaches though.
Originally published Tuesday 18 March 2014, with subsequent revisions, updates to lapsed URLs, etc.
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A map of the solar system for your own grand tour of the planets
4 February 2014
Back in the 1960’s the Jet Propulsion Laboratory, a US space agency, was keen to organise a “Grand Tour” of the solar system’s outer planets, by taking advantage of a planetary alignment that would occur in the late 1970’s. They hoped to send up to four automated probes to take a closer look at Jupiter, Saturn, Uranus, Neptune, and Pluto.
Funding cuts thwarted the idea, though NASA deep space probe Voyager 2, launched in 1977, was able to fly by Jupiter, Saturn, Uranus, and Neptune.
There won’t be another such alignment of the outer planets until well into the twenty-second century. But thanks to Pasadena based designer and illustrator Paul Rogers, who has created a map of the solar system for tourists, you may be able to plan your own jaunt about the planets in the meantime.
Originally published Tuesday 4 February 2014, with subsequent revisions, updates to lapsed URLs, etc.
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astronomy, design, illustration, legacy, science
Not every moon is a moon, most are captured objects
9 January 2014
Here’s a 2010 photo, taken by the European Space Agency’s Mars Express probe, of Phobos, one of two… moons orbiting Mars. But that’s not a moon. And nor is Deimos, Mars’ second so-called moon. In reality they’re merely random rocks captured by the Red Planet at some point in the past.
Take a look at Earth’s moon. The Moon. It’s elegant, sizeable, and spherical. The same cannot be said of the rocks orbiting Mars, a couple of unfortunate asteroids that once strayed a tad too close to the fourth planet. Most of the outer planets of the solar system have moons similar in stature to Earth’s satellite, but they also host a bunch of minuscule, oddly shaped rocks, called moons simply because they orbit the planet in question.
It makes me think it is time to consider what really constitutes a moon. If Pluto can no longer be regarded as a planet, why then must every last rock that has been pulled into orbit by a planet, be called a moon? Surely such bodies should adhere — like planets, real planets — to some sort of criteria before being called a moon.
Being pretty much spherical, and of a certain size and mass, could form basic benchmarks, and anything under a certain size should be referred to as a captured object rather than a moon. Sorry Mars, but both your orbiting companions, Phobos and Deimos, are captured objects, not moons.
Originally published on Thursday 9 January 2014.
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astronomy, legacy, Mars, Pluto, science
When galaxies collide, coming to the night sky in four billion years
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.
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