30-metre asteroid set skimming past Earth in October will test Nasa's doomsday 'planetary defence sy

[jpak]

30-metre asteroid set skimming past Earth in October will test Nasa's doomsday 'planetary defence system'

http://www.dailymail.co.uk/sciencetech/article-4746010/Nasa-test-defence-asteroid-skims-past-Earth.html

On October 12, a 30-metre is set to make a 'close' flyby of Earth.

The asteroid, named 2012 TC4, will pass just 4,200 miles (6,800 kilometres) from Earth for the first time since it went out of range in 2012.

Nasa is using this opportunity to test it's 'planetary defence system' put in place to protect Earth from a doomsday asteroid threat.

Asteroid 2012 TC4 is estimated to be between 10 and 30 metres in size.

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[uppityperson]

1. A more reputable site says 170,000 mi more likely, not less than 4,200 mi.

Still within the moon's orbit.

http://earthsky.org/space/near-earth-asteroid-2012-tc4-close-pass-october-2017

[muriel_volestrangler]

2. Daily Mail misleads - "will pass 4,200 miles from Earth" later revealed as "up to 170,000 miles"

In their bullet points, first few paragraphs, and first illustration, they state it will pass 4,200 miles from Earth. But if you read several paragraphs further, that changes to "will pass no closer than 4,200 miles from Earth, although it will more likely pass much farther away, as far as 170,000 miles" - and that's the way NASA actually puts it: https://www.jpl.nasa.gov/news/news.php?feature=6906 .

This matters, because if people thought that 4,200 miles was the most likely range, they might rightly think "they can't be that certain about something last seen 5 years ago - could it come closer?" But if it's more likely to be much farther away, then they've already looked at how certain they are, to say 4,200 is as closely as they possibly think it could get.