Low-flying rocks

From Stuff The Herald:  ‘Potentially hazardous’ asteroid heading towards Earth at 108,800km/h, and in the story

It is the largest space rock to brush past our planet this year and previous research has found a rock of this size could plunge Earth into a mini-ice age if it hit.

The impact would cause average temperatures around the world to fall by as much as 8°C, according to a 2016 study on the effects of a collision with a 0.6-mile-wide (1km) asteroid.

“These would not be pleasant times,” Charles Bardeen, of the National Center for Atmospheric Research, said during a presentation at the American Geophysical Union (AGU).

In the “worst case scenario”, soot would remain in the atmosphere for around 10 years, while dust take six years to settle back on Earth.

Fortunately Nasa does not think this asteroid will collide with Earth.

NASA would put that more strongly. From NASA/JPL Asteroid Watch: Asteroid 2002 AJ129 to Fly Safely Past Earth February 4,

At the time of closest approach, the asteroid will be no closer than 10 times the distance between Earth and the Moon (about 2.6 million miles, or 4.2 million kilometers).

“We have been tracking this asteroid for over 14 years and know its orbit very accurately,” said Paul Chodas, manager of NASA’s Center for Near-Earth Object Studies at the Jet Propulsion Laboratory, Pasadena, California. “Our calculations indicate that asteroid 2002 AJ129 has no chance – zero – of colliding with Earth on Feb. 4 or any time over the next 100 years.”

The @asteroidwatch twitterwallah is off because of the government shutdown, but was relatively patiently answering Twitter questions in both English and Spanish until Friday.

Part of the problem is that NASA uses “potentially hazardous” for any asteroid approaching within 1/20th of the distance to the sun, because these are the ones they want to track to be sure that they aren’t actually hazardous.  It’s an unfortunate term because it sounds dangerous when it isn’t.