Celestial flybys set to thrill

January 6, 2013 by Richard Ingham
This handout photo released on December 27, 2012 by ESO shows an artist's impression of the disc of gas and cosmic dust around the young star HD 142527. Astronomers are gearing up for thrills this year when Earth gets buzzed by two rogue asteroids and two comets, including a wanderer last seen by the forerunners of mankind.

Astronomers are gearing up for thrills this year when Earth gets buzzed by two rogue asteroids and two comets, including a wanderer last seen by the forerunners of mankind.

The guardians who scour the heavens for dangerous are currently closely tracking an asteroid called 99942 Apophis.

Named after the god of evil and darkness in Egyptian mythology, Apophis measures around 270 metres (877 feet) across, a mass able to deliver more energy than 25,000 Hiroshima bombs if it ever smashed into Earth.

Apophis sparked some heart-stopping moments when it was first detected in 2004.

Early calculations suggested a 2.7-percent probability of a collision in 2029, the highest ever seen for an asteroid, but the risk was swiftly downgraded after more observations.

Even so, for April 13, 2036, "there is still a tiny chance of an impact," says 's fabled Jet Propulsion Laboratory (JPL), which puts the risk at about one in 250,000.

One of the big unknowns is the Yarkovsky effect, a phenomenon discovered by a Russian engineer at the start of the 20th century.

This NASA image shows a solar eruption as it gracefully rises up from the Sun on December 31, 2012, twisting and turning. Magnetic forces drove the flow of plasma, but without sufficient force to overcome the Sun's gravity much of the plasma fell back into the Sun. The length of the eruption extended about 160,000 miles (257,000 Km) out from the Sun.

A slowly rotating body that orbits close to the Sun experiences heating on one side of its body that then cools at "night" as it turns over.

This alternate heating and cooling can cause a tiny momentum, depending on the body's spin and amount of area that warms.

The question is whether, over time, the Yarkovsky effect is accelerating Apophis, thus skewing estimates for future approaches.

Seeking clues, NASA's deep-space radars at Goldstone, in California's , and at Arecibo in Puerto Rico will be scanning Apophis, which on January 9 will pass by at some 14.5 million kilometres (nine million miles).

"Using new measurements of the asteroid's distance and line-of-sight velocity, we hope to reduce the orbital uncertainties and extend the interval over which we can compute the motion into the future," JPL's Lance Benner said in an email.

This image obtained on December 31, 2012 shows the NASA/ESA Hubble Space Telescope view of the bright star-forming ring that surrounds the heart of the barred spiral galaxy NGC 1097.
"It's possible that the new measurements improve the to the point that we can completely rule out an impact."

On February 15, a 57-metre (185-feet) asteroid, 2012 DA14, will skim the planet at just 34,500 kilometres (21,600 miles). In other words, it will spookily fly by inside the orbit of geostationary satellites.

"It's going to be the closest predicted flyby of an asteroid," says Mark Bailey, director of the Armagh Observatory in Northern Ireland.

"Because it is coming so close, even amateur astronomers will be able to watch it as it moves against background stars, and it may be visible through binoculars."

Comets—seen by the superstitious as harbingers of great events—could make 2013 a memorable year, astronomers hope.

Lonely travellers of the cosmos, comets comprise giant clumps of primeval ice and dust, formed in the infancy of the , which loop around the Sun at intervals that can vary from years to aeons.

As they get closer to our star, solar heat warms the comet's surface, causing it to spew out gases and shed a dusty trail which becomes reflected as a "tail" in the Sun's rays.

First up is Comet 2011 L4 (PANSTARRS), whose name comes from the telescope at the University of Hawaii which spotted it in 2011.

PANSTARRS could be at its brightest from March 8 to 12, according to US specialist Gary Kronk (cometography.com/current_comets.html).

This combination image shows a NASA file photo of the Earth and a January 2, 2013 NASA/SDO (Solar Dynamics Observatory) handout image of the Sun. Comets—seen by the superstitious as harbingers of great events—could make 2013 a memorable year, astronomers hope.

The biggest excitement is being reserved for Comet ISON, named after the International Scientific Optical Network, whose telescope was used by Russian astronomers Vitaly Nevski and Artyom Novichonok to make the find last September.

Right now, it is unclear how bright ISON will be, but by some calculations it could become visible to the naked eye by late November and maybe linger brilliantly for months, becoming a once-a-century event.

ISON is an extraordinary beast, for it last returned to Earth 10 million years ago, or more, says Bailey.

"It's a 'new comet', which comes from a region of the Solar System that's called the Oort Cloud, an extensive system that extends from around a thousand times the distance of the Earth to the Sun to around 100,000-200,000 times this distance," Bailey says.

"If you imagine a model of the Solar System whereby the Sun's a football in the centre of a football pitch and the Earth is on the perimeter, then this comet has come effectively from Australia. That's the scale of things."

Explore further: New 'Sun-skirting' comet could provide dazzling display in 2013

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4.1 / 5 (9) Jan 06, 2013
great article on the asteroids and comets expected in 2013 and the coming years.

On the other hand, every single picture and caption is completely irrelevant to the asteroids and comets mentioned....I was rather confused by why they were included.
3.7 / 5 (3) Jan 10, 2013
Saying, "Oh no - we are fucked", when a big one is found to be coming straight at us, is not much good

That's not entirely true. While a really big one might come close to sterilizing the planet, the more common sizes aren't that bad. If you know we are going to be hit, you can start to do things to plan. You can have farmers grow extra food, bottle water, stock up on fuels, batteries, blankets, radios, etc. If you figure out where it's going to hit, you might even build shelters and/or evaccuate people and infrastructure. You could do things like back up databases and move corporate headquarters, libraries and museums.

With enough warning there are a few things you can do, even if you can't stop it.
5 / 5 (3) Jan 10, 2013
Having a telescope and going "Oh my god - it's gunna hit us!" (or not) is like masturbating over a picture of someone, and calling it a date.

So what do you suggest? First building interceptors before we know what's out there? And then finding out that what is out there is entirely different and we just wasted a lot of time and money on building inefficient stuff?

(Actually, now that I write this: Isn't this the way the military-industrial complex works? But I digress...)

The point is:
1) FIRST open eyes.
2) THEN select tools.

Not the other way around.

People are discussing what kind of options we have. And the better eyes (read: the more prewarn time) we have the better we can tailor the response (nukes probably being wholly uneffective for this, BTW)

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