Comet tagged posts

A diagram showing how the meteors will appear to emanate from a radiant in the constellation of Gemini, located in the east in the evening sky. Credit: Greg Smye-Rumsby / Astronomy Now

From 13 to 15 Dec, weather permitting, skywatchers across the world will be looking up as the Geminid meteor shower reaches its peak, in potentially one of the best night sky events of the year. Tens of ‘shooting stars’ or meteors may be visible each hour (the theoretical maximum under ideal conditions is about 120/hr). Meteors are the result of small (mm- to cm-sized) particles entering the Earth’s atmosphere at high speed, burning up and superheating the air around them, which then shines as a characteristic short-lived streak of light...

This is a graphic depicting the orbit of asteroid 2015 TB145. The asteroid will safely fly past Earth slightly farther out than the moon’s orbit on Oct. 31 at 10:05 a.m. Pacific (1:05 p.m. EDT and 17:05 UTC). Credit: NASA/JPL-Caltech

NASA scientists are tracking the upcoming Halloween flyby of asteroid 2015 TB145 with several optical observatories and the radar capabilities of the agency’s Deep Space Network at Goldstone, CA. The asteroid will fly past Earth at a safe distance slightly farther than the moon’s orbit on Oct. 31 at 10:01 am PDT. The flyby of the estimated 1300-ft-wide asteroid is a science target of opportunity, allowing instruments on “spacecraft Earth” to scan it during the close pass.

Asteroid 2015 TB145 was discovered on Oct...

For >30 years, scientists have argued about a controversial hypothesis relating to periodic mass extinctions and impact craters – caused by comet and asteroid showers – on Earth. Now scientists have concluded that mass extinctions occurring over the past 260 million years were likely caused by comet and asteroid showers.

A graph showing how the rate of cratering has changed on Earth over time. The arrows indicate the dates of mass extinctions. Credit: Michael Rampino / NYU

Michael Rampino, NYU geologist, and Ken Caldeira, a scientist in the Carnegie Institution’s Department of Global Ecology, offer new support linking the age of these craters with recurring mass extinctions of life, including the demise of the dinosaurs...