Using the Gemini North telescope on Mauna Kea, Hawai‘i a team of astronomers from the University of Hawaii’s Institute for Astronomy (IfA) have confirmed that the chance of asteroid 2011 AG5 impacting Earth in 2040 is no longer a significant risk – prompting a collective sigh-of-relief. Previously, scientists estimated that the risk of this 140-meter-diameter (about the length of two American football fields) asteroid colliding with the Earth was as high as one in 500.
If this object were to collide with the Earth it would have released about 100 megatons of energy, several thousand times more powerful than the atomic bombs that ended World-War II. Statistically, a body of this size could impact the Earth on average every 10,000 years.
Newly-discovered asteroid 2012 BX34 is flying past Earth today only 77,000 km (0.2 lunar distances) away. There is no danger of a collision with the 14-meter wide space rock.
X2 Solar Flare
Departing sunspot 1402 unleashed an X2-class solar flare today, Jan. 27th, at 18:37 UT. Sunspot 1402 is rotating onto the far side of the sun, so the blast site was not facing Earth. Nevertheless, energetic protons accelerated by the blast are now surrounding our planet, and an intensifying S1-class radiation storm is in progress.
An asteroid impact with the earth can really ruin your day: just consider the dinosaurs. Most asteroids, also known as minor planets, orbit the sun beyond the planet Mars and present no danger, but there is a class of asteroids whose orbits cross the orbit of the earth. If one of these asteroids and the earth are at the same point in their orbits at the same time, a collision could occur. Called Near Earth Objects (NEOs), astronomers are interested in discovering as many of these as possible, and then tracking them in order to compute more accurate orbits. In this way, if a potential future collision were to be identified many years in advance, space probes could carry out steps to tweak the path of the NEO and deflect the collision. A program to track NEOs is being carried out at NOAO by Mark Trueblood with Robert Crawford (Rincon Ranch Observatory) and Larry Lebofsky (Planetary Science Institute). And last summer, a Beloit College student, Morgan Rehnberg, has developed a computer program (PhAst), available via the web, to help with this effort.
Asteroids move quickly across the sky, so in order to recover and track them, fast and accurate data reduction and analysis is essential. Unlike most of the data that astronomers work with, tracking a fast moving asteroid requires that the observer view multiple digital images obtained at the telescope by blinking between them, almost like a movie. In addition, accurate coordinates locating the NEO in the sky need to be computed. (Termed right ascension and declination, these are similar in concept to the latitude and longitude of a position on earth.) While there are many software packages that amateur and professional astronomers use (Maxim DL, Astrometrica) none did exactly what the group required. Seeing the need for better software but not having the time to devote to the task of writing it, Trueblood saw this as an ideal project for a summer student.
Full Story: http://www.noao.edu/news/2011/pr1107.php
NASA Scientists working with the 230-foot-wide (70-meter) Deep Space Network antenna at Goldstone, Calif., have released a second, longer, and more refined, movie clip of asteroid 2005 YU55. The images were generated from data collected at Goldstone on Nov. 7, 2011, between 11:24 a.m. and 1:35 p.m. PST (2:24 p.m. and 4:35 p.m. EST).
The movie clip can be found at: http://1.usa.gov/YU55 .
Each of the 28 frames required 20 minutes of data collection by the Goldstone radar. At the time of the observations, 2005 YU55 was approximately 860,000 miles (1.4 million kilometers) from Earth. The resolution is about 13 feet (4 meters) per pixel. 2005 YU55 takes approximately 18 hours to complete one rotation, so the rotation in the movie appears much more rapid than the actual asteroid rotation speed.
The Goldstone observations utilized a new system to obtain images with a resolution of 4 meters, which is five times finer than the highest resolution previously possible at Goldstone.
NASA radars are monitoring 2005 YU55, an asteroid the size of an aircraft carrier, as it heads for a Nov. 8th flyby of the Earth-Moon system. There is no danger to our planet. At closest approach on Tuesday at 3:28 pm PST (23:28 UT), the 400m-wide space rock will be 324,600 kilometers away, about 85% the distance from Earth to the Moon.
Professional astronomers are eagerly anticipating the flyby as the asteroid presents an exceptionally strong radar target. Powerful transmitters at Goldstone and Arecibo will ping the space rock as it passes by, revealing the asteroid’s shape and texture in crisp detail, and pinpointing its orbit for future flyby calculations.
Also, from Sky & Telescope…
Earth is about to be visited by the largest close-approaching asteroid on record. Known as 2005 YU55, it is about a quarter mile (400 m) across, round, and quite dark. When it comes closest to us, at 6:28 p.m. EST (23:28 Universal Time) on November 8th, it will be 198,000 miles (319,000 km) from Earth’s surface — closer than the Moon’s orbit. Professional astronomers around the world will closely follow the asteroid as it glides across the sky.
Weather permitting, backyard skywatchers also have a chance to spot this interloper. A few hours after passing closest to us, it will peak in brightness at magnitude 11.1, roughly 100 times fainter than the limit of human vision. “The good news,” says Alan MacRobert of Sky & Telescopemagazine, “is that you should be able to spot the asteroid with your telescope if it has an aperture of at least 6 to 8 inches.”
NASA scientists will be tracking asteroid 2005 YU55 with antennas of the agency’s Deep Space Network at Goldstone, Calif., as the space rock safely flies past Earth slightly closer than the moon’s orbit on Nov. 8. Scientists are treating the flyby of the 1,300-foot-wide (400-meter) asteroid as a science target of opportunity – allowing instruments on “spacecraft Earth” to scan it during the close pass.
Tracking of the aircraft carrier-sized asteroid will begin at 9:30 a.m. local time (PDT) on Nov. 4, using the massive 70-meter (230-foot) Deep Space Network antenna, and last for about two hours. The asteroid will continue to be tracked by Goldstone for at least four hours each day from Nov. 6 through Nov. 10. Radar observations from the Arecibo Planetary Radar Facility in Puerto Rico will begin on Nov. 8, the same day the asteroid will make its closest approach to Earth at 3:28 p.m. PST.
The trajectory of asteroid 2005 YU55 is well understood. At the point of closest approach, it will be no closer than 201,700 miles (324,600 kilometers) or 0.85 the distance from the moon to Earth. The gravitational influence of the asteroid will have no detectable effect on anything here on Earth, including our planet’s tides or tectonic plates. Although 2005 YU55 is in an orbit that regularly brings it to the vicinity of Earth (and Venus and Mars), the 2011 encounter with Earth is the closest this space rock has come for at least the last 200 years.
For the first time, observations coordinated by ESA’s space hazards team have found an asteroid that comes close enough to Earth to pose an impact threat. The space rock was found by amateur astronomers, highlighting the value of ‘crowd-sourcing’ to science and planetary defence.
The discovery of asteroid 2011 SF108 was made by the volunteer Teide Observatory Tenerife Asteroid Survey (TOTAS) team during an observation slot sponsored by ESA’s Space Situational Awareness (SSA) programme in September.
The four-night survey used the 1m-aperture telescope at ESA’s Optical Ground Station at Teide on Tenerife in the Canary Islands.
New observations by NASA’s Wide-field Infrared Survey Explorer, or WISE, show there are significantly fewer near-Earth asteroids in the mid-size range than previously thought. The findings also indicate NASA has found more than 90 percent of the largest near-Earth asteroids, meeting a goal agreed to with Congress in 1998.
Astronomers now estimate there are roughly 19,500 — not 35,000 — mid-size near-Earth asteroids. Scientists say this improved understanding of the population may indicate the hazard to Earth could be somewhat less than previously thought. However, the majority of these mid-size asteroids remain to be discovered. More research also is needed to determine if fewer mid-size objects (between 330 and 3,300-feet wide) also mean fewer potentially hazardous asteroids, those that come closest to Earth.
The results come from the most accurate census to date of near-Earth asteroids, the space rocks that orbit within 120 million miles (195 million kilometers) of the sun into Earth’s orbital vicinity. WISE observed infrared light from those in the middle to large-size category. The survey project, called NEOWISE, is the asteroid-hunting portion of the WISE mission. Study results appear in the Astrophysical Journal.