Asteroid Apophis is expected to be visible in the Earth sky on Wednesday, Jan. 9. The asteroid is quite far relative to the moon's distance from the planet. But in 2004, scientists feared an eventual impact with this 270-meter rock in space.
Here are six (6) things to know about asteroid Apophis:
6. Near-Earth asteroid 99942 Apophis, which measures about 270 meters in diameter, was discovered on June 19, 2004. Roy A. Tucker, David J. Tholen and Fabrizio Bernardi of the Kitt Peak National Observatory were all credited for spotting Apophis.
5. "Apophis" was popularized by the TV series Stargate SG-1 as the enemy of the Ancient Egyptian sun-god Ra: Apep, an evil serpent. (Tholen and Tucker are reportedly fans of Stargate.)
4. The Apophis flyby on Jan. 9 is expected to occur from a distance of 14.5 million kilometres above the Earth surface. This distance is not particularly alarming. But initial studies in Dec. 2004 indicated a possible impact to Earth or the Moon by the year 2029.
3. When further studies revealed that Apophis was not likely to impact Earth or the Moon by 2029, another alarming scenario surfaced. Researchers saw Apophis could potentially pass through a gravitational keyhole that would lead to an Earth impact by 2036. This, too, later proved to be not highly likely after improved studies of the asteroid's orbit.
2. In Bill McGuire's 2005 book, "Global Catastrophes: A Very Short Introduction," Apophis will pass Earth within the orbits of geosynchronous communication satellites on April 13, 2029 (Friday). The next approach is in the year 2036. Astronomer Dr Stuart Clark wrote in The Guardian there is still a "chance of an impact" in 2036.
1. Apophis is still classified "Potentially Hazardous Asteroids" in the records of the International Astronomical Union's Minor Planet Center. "On Friday 13 April 2029, Apophis will slip past the Earth just 30,000km above our heads - less than one-tenth the distance of the moon," wrote Dr Clark.
Despite the expected close encounters in 2029 and 2036, Dr Clark said further studies ahead of the next Apophis flybys should improve action plans against potentially dangerous asteroids.