Showing all posts about astronomy
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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astronomy, legacy, milkomeda, Milky Way
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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