Monday, October 12, 2015

Asteroid 2015 TC25 to Whiz Very Close by Earth

Asteroid 2015 TC25 orbit diagram. Credit: NASA

An asteroid is slated to give our planet a very close shave tomorrow, Oct. 13. The space rock, dubbed 2015 TC25 will pass by Earth at a distance of about 0.3 LD (lunar distances). This means that it will miss us by approximately 115,320 km (71,670 miles), according to observations. Luckily, the asteroid is too small to do any harm. Having only 5 meters in diameter, as it is estimated, 2015 TC25 would burn up in Earth’s atmosphere if on collision course.

This asteroid passed Earth several times in the past. The first known fly-by took place on Oct. 15, 1977 when it missed our planet at a distance of 0.37 LD and the moon at 0.29 LD. Other fly-bys occurred in 1986, 1992, 1994, 2007, 2008 and 2009. The next close approach will happen on Mar. 26, 2017 when 2015 TC25 will miss Earth at a distance of 8.9 LD.

We could expect some spectacular bolides, fireballs, and meteors this month and especially large ones in the coming days, before and following the passing of 7 small mountain-sized near-Earth objects (NEO): asteroids and one comet, diameters ranging from 500 meters to 2.6 km, that will safely pass this month.

Every night, a network of NASA all-sky cameras scans the skies above the U.S. for meteoritic fireballs. Automated software maintained by NASA's Meteoroid Environment Office calculates their orbits, velocity, penetration depth in Earth's atmosphere and many other characteristics. On Oct. 12, the network reported 26 fireballs.

Two house-sized asteroids: 2015 TK21 and 2015 TG24 passed at a safe distance of about 4 LD on Oct. 12. 2015 TK21 will also fly by Mars on Mar. 17, 2026 at about 9 LD. Another space rock worth noticing is 2014 UR, a 21-meters-wide asteroid that will miss our planet by 3.8 LD.

As of Oct. 12, 2015 there were 1618 known potentially hazardous asteroids (PHAs). PHAs are space rocks larger than approximately 100 meters that can come closer to Earth than 19.5 LD. None of the known PHAs is on a collision course with our planet, although astronomers are finding new ones all the time.