Showing all posts about astronomy
For the universe is a hologram and I have touched the sky
25 October 2010
All sorts of ideas have been devised in an effort to make sense of the universe, some more… notable than others. For instance, a couple of years ago New Zealand scientist Brian Whitworth speculated that the cosmos was just a giant virtual reality simulation (Internet Archive link).
Meanwhile US astrophysicist Craig Hogan, who in 2008 ventured that the universe is a hologram, is now preparing to test the idea, after spending the last couple of years building the world’s most precise clock.
Black hole physics, in which space and time become compressed, provides a basis for math showing that the third dimension may not exist at all. In this two-dimensional cartoon of a universe, what we perceive as a third dimension would actually be a projection of time intertwined with depth. If this is true, the illusion can only be maintained until equipment becomes sensitive enough to find its limits. “You can’t perceive it because nothing ever travels faster than light,” says Hogan. “This holographic view is how the universe would look if you sat on a photon.”
Originally published Monday 25 October 2010, with subsequent revisions, updates to lapsed URLs, etc.
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astronomy, legacy, physics, science
Colliding galaxies, an insight into Milkomeda’s formation?
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 an indication of what to expect when Milkomeda does form.
Originally published Sunday 12 July 2009
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The chances of colliding with a star are a million to one
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.
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Lost in space, the final days of the Solar system
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.
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When galaxies collide we will be living in Milkomeda
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.
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What will happen when Antares explodes?
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.
It has been found however that a supernova needs to be within 26 light years of Earth to cause any sort of harm, and Antares is some 600 light years away.
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.
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Detecting and defending Earth from asteroids, other threats
29 September 2008
The Association of Space Explorers (ASE) is calling on the United Nations (UN) to co-ordinate efforts to defend Earth from “potentially catastrophic asteroid threats“.
The report asks the UN to assume responsibility for responding to potentially catastrophic asteroid threats. “For 4.5 billion years, we’ve been bashed continuously by asteroids. It’s time for that to stop,” former Apollo 9 astronaut Rusty Schweickart told the assembly. The ASE’s vision is first for a global information network, coordinated by the UN, that uses data from ground- and space-based telescopes to find, track and rate the risk of near-Earth objects (NEOs).
Originally published Monday 29 September 2008, with subsequent revisions, updates to lapsed URLs, etc.
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Uneven heat emission sending Pioneers 10 and 11 off course
7 July 2008
The mystery surrounding the unexplained course deviations of deep space probes Pioneers 10 and 11, which are currently somewhere in the vicinity of the Solar System’s Kuiper Belt, may have been solved. At least partly, that is.
Slava Turyshev, of NASA’s Jet Propulsion Laboratory, has spent the last two years studying data from the probes, which were launched in the 1970s, and concluded that uneven heat build-up across their structures is causing the trajectory anomalies:
Pioneer 11 gives off heat in certain directions more than others. The uneven heat emission is enough to nudge the spacecraft off course, accounting for 28% to 36% of the anomaly detected when Pioneer 11 was 3750 million kilometres, or 25 times the Earth-sun distance, away from us.
Originally published Monday 7 July 2008.
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Pioneers 10 and 11 courses inexplicably varying at Kuiper Belt
15 September 2004
Something weird is happening out on the boundary of our solar system, an area called the Kuiper Belt, where NASA space probes Pioneers 10 and 11 are presently located.
Both deep space probes, launched over thirty years ago, traversed the inner region of the solar system almost exactly according to plan.
Since passing beyond the orbit of Pluto though, events have taken an unexpected turn: both probes appear to be inexplicably deviating from their projected courses.
And no one can work out why. Some scientists think long held ideas on the effects of gravity over extended distances may be need to be re-thought. Others say that both probes may be leaking gases, which is contributing to the change in their trajectories.
This mystery has led to calls for a new deep space mission to see what’s happening out at the Kuiper.
By fitting a Pioneer follow-up probe with new measuring equipment, navigational device and communications gear, it should be possible to discover if the probes are in the grip of a new force of nature.
A new force of nature? Perhaps Star Wars director George Lucas’ far, far, away galaxy may not be all that distant after all…
Originally published Wednesday 15 September 2004.
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astronomy, legacy, Pluto, science
The Big Bang might have been big, but it sounded like a hum
31 October 2003
Judging by the amount of press it generates, it seems we just love talking about the Big Bang, the theory that explains the existence of the universe. And why not? We wouldn’t be here now talking about it, if it er, hadn’t have happened. Theoretically speaking that is.
The latest revelations published in New Scientist suggest the Big Bang was more of a deep hum rather than an explosive, booming, bang. Whether it was a bang or a hum though, there’s no doubting its volume, which was certainly loud.
Another news service carrying the same story compared the noise levels as being similar to a jet aeroplane with its engines operating at full power just ten or so metres above your house.
A little like the noise that Concorde used to create perhaps? Theoretically speaking that is .
Originally published Friday 31 October 2003, with subsequent revisions, updates to lapsed URLs, etc.
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