As­teroid’s shock close shave with Earth

The Dominion Post - - News -

A medium-sized as­teroid sur­prised as­tronomers with an un­ex­pected near-miss of Earth at the week­end.

EarthSky re­ported that the as­teroid – la­belled 2018 GE3 – came within about 192,300 kilo­me­tres of Earth at its clos­est point at 6.41pm on Sun­day.

That’s a lit­tle under half the dis­tance be­tween the Earth and the Moon.

The as­teroid’s di­am­e­ter was es­ti­mated to be be­tween 48 me­tres and 110m, and it was trav­el­ling at 106,497kmh.

Had it en­tered the at­mos­phere, a great por­tion of the as­teroid would have bro­ken up, but some might have made it through to the Earth’s sur­face, EarthSky said.

‘‘An as­teroid this big is ca­pa­ble of caus­ing some re­gional dam­age, de­pend­ing on var­i­ous fac­tors such as com­po­si­tion, speed, en­try an­gle, and lo­ca­tion of im­pact.’’

In con­trast, the space rock that ex­ploded in an air burst over Chelyabinsk, Rus­sia, in Fe­bru­ary 2013, was about 20m in di­am­e­ter.

Ac­cord­ing to Nasa, that as­teroid gen­er­ated a shock wave that blew out win­dows over 500 square kilo­me­tres.

More than 1600 peo­ple were in­jured in the blast, mostly be­cause of bro­ken glass.

The Chelyabinsk as­teroid was un­de­tected be­fore it en­tered the at­mos­phere.

As­teroid 2018 GE3 was first ob­served the day be­fore its clos­est pass, by the Catalina Sky Sur­vey in Ari­zona, a Nasa-funded project sup­ported by the Near Earth Ob­ject Ob­ser­va­tion Pro­gram. The sur­vey’s task is to dis­cover and track near-Earth ob­jects.

Space.com said 2018 GE3 was up to 3.6 times the size of the space rock that lev­elled 2000 square kilo­me­tres of for­est when it ex­ploded over Siberia in June 1908.

CNET said 2018 GE3 was among the largest space rocks to come so close to Earth.

‘‘A cou­ple of times a week, on av­er­age, an as­teroid will come closer than the dis­tance to the Moon but most of those are hunks about the size of a bus or a house.’’

A space rock the size of a ware­house passed close to Earth at the week­end. The white line shows 2018 GE3’s or­bit, while the Earth’s is in blue.

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