Asteroid in close encounter with Earth

The passage of asteroid 2012 DA14 through the Earth-moon system on February 15. Image courtesy of: NASA / JPL-Caltech

Good news for soppy romantics – the world isn’t going to come to an end after Valentine’s Day.

At least that’s according to space boffins who are tracking an asteroid that is set to hurtle past Earth on February 15, missing our planet’s surface by a mere 36 000km.

The near-Earth asteroid, called 2012 DA14, is to make a record close approach to Earth for an object of its size (45m in diameter). A repeat can be expected in about 40 years.

The close encounter has got the Astronomical Society of Southern Africa’s Durban centre very excited – but not concerned that it will crash into Earth, destroy a city or cause a tsunami.

“Hundreds of asteroids strike the Earth’s atmosphere daily and burn out before they hit the ground,” said Logan Govender, chairman of the society’s Durban centre.

“What makes this asteroid different is that it would pass inside the ring of the geosynchronous weather and communication satellites orbit, about 36 000km away from the Earth, the closest an asteroid of this size would approach Earth.”

According to the book “Orbital Mechanics”, a geosynchronous orbit is an orbit around Earth with an orbital period of one sidereal day (23 hours, 56 minutes and 4 seconds), matching Earth’s sidereal rotation period. An object in this orbit would return to the same spot in the sky after one day.

Govender explained that while this may be the closest an asteroid of this size would pass Earth, 36 000km was still quite a distance.

“The distance from here to London is about 10 000km, so it would be that trip three times over.”

He said it would not crash into Earth’s surface, but even if it did, 70 percent of the planet is covered by water, which would be the most likely landing spot.

Should it land in the sea, it would cause a tsunami, said Govender. Should it hit land, it would have the capacity to wipe out a city the size of Durban.

Nasa said on its website it can accurately predict the asteroid’s path, and that there was no chance that 2012 DA14 might be on a collision course with Earth.

The asteroid was discovered last February by astronomers at the La Sagra Sky Survey programme in southern Spain.

At the time, Nasa reported that the asteroid had just made a fairly distant passage by Earth, about seven times further than the moon.

“Since 2012 DA14’s orbital period around the sun has been about 368 days, which is very similar to the Earth’s, the asteroid made a series of annual close approaches,” according to Nasa. “This year’s the closest approach, and is the closest the asteroid will come for at least three decades.”

However, the agency said it would only appear as a point of light in the biggest optical telescopes.

Govender said it would be too small for the naked eye but could be seen using binoculars fixed on a tripod or a telescope.

The best viewing will be in east Europe, parts of Asia and Australia. It would be closest to Earth next Friday at 9.30pm in South Africa.

Nasa said that although it would be close enough to pass inside the ring of geosynchronous satellites, it would still be well above most of them, including the International Space Station.

noelene.barbeau@inl.co.za