Monday, March 7, 2016

Hundreds of 60-mile comets could pose grave threat to earth

Also: Meteor Activity Outlook for March 5-11, 2016

Scientists are warning that hundreds, possibly thousands, of rogue comets up to 160 miles long have the potential to collide with earth, with devastating results.

The comets in question are called Centaur comets and can travel around 150,000 miles an hour. They are found far outside of the asteroid belt between Mars and Jupiter.

Even the smallest of the Centaurs could engulf the world in flames if it collides. This has sparked a great deal of research into finding their locations. However, about 90% of them still need to be found.
Professor Bill Napier, co-author of the report from the University of Buckingham, said: "In the last three decades we have invested a lot of effort in tracking and analyzing the risk of a collision between the Earth and an asteroid."

He continues, "Our work suggests we need to look beyond our immediate neighbourhood too, and look out beyond the orbit of Jupiter to find Centaurs... If we are right, then these distant comets could be a serious hazard, and it's time to understand them better."

Asteroid Impact Event Possible! Four On The Way

Meteor Activity Outlook for March 5-11, 2016

During this period the moon reaches its new phase on Tuesday March 8th. On that date the moon will be located near the sun and will be invisible at night. As the week progresses the waxing crescent moon will enter the evening sky but will not interfere with the observing of meteor activity. The estimated total hourly meteor rates for evening observers this week is near 3 for observers located in the northern hemisphere and 4 for observers located south of the equator. For morning observers the estimated total hourly rates should be near 8 as seen from mid-northern latitudes (45N) and 13 as seen from tropical southern locations (25S). The actual rates will also depend on factors such as personal light and motion perception, local weather conditions, alertness and experience in watching meteor activity. Note that the hourly rates listed below are estimates as viewed from dark sky sites away from urban light sources. Observers viewing from urban areas will see less activity as only the brightest meteors will be visible from such locations.

The radiant (the area of the sky where meteors appear to shoot from) positions and rates listed below are exact for Saturday night/Sunday morning March 5/6. These positions do not change greatly day to day so the listed coordinates may be used during this entire period. Most star atlases (available at science stores and planetariums) will provide maps with grid lines of the celestial coordinates so that you may find out exactly where these positions are located in the sky. A planisphere or computer planetarium program is also useful in showing the sky at any time of night on any date of the year. Activity from each radiant is best seen when it is positioned highest in the sky, either due north or south along the meridian, depending on your latitude. It must be remembered that meteor activity is rarely seen at the radiant position. Rather they shoot outwards from the radiant so it is best to center your field of view so that the radiant lies at the edge and not the center. Viewing there will allow you to easily trace the path of each meteor back to the radiant (if it is a shower member) or in another direction if it is a sporadic. Meteor activity is not seen from radiants that are located below the horizon. The positions below are listed in a west to east manner in order of right ascension (celestial longitude). The positions listed first are located further west therefore are accessible earlier in the night while those listed further down the list rise later in the night.

These sources of meteoric activity are expected to be active this week.

The center of the large Anthelion (ANT) radiant is currently located at 11:52 (178) +00. This position lies in western Virgo, only 2 degrees south of the 4th magnitude star known as Zavijava (Beta Virginis). Due to the large size of this radiant, Anthelion activity may also appear from the nearby constellations of Corvus, Crater, Coma Berenices, and Leo as well as Virgo. This radiant is best placed near 0100 local standard time (LST), when it lies on the meridian and is located highest in the sky. Rates at this time should be near 3 per hour no matter your location. With an entry velocity of 30 km/sec., the average Anthelion meteor would be of slow velocity.
As seen from the mid-northern hemisphere (45N) one would expect to see approximately 5 sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near 2 per hour. As seen from the tropical southern latitudes (25S), morning rates would be near 10 per hour as seen from rural observing sites and 3 per hour during the evening hours. Locations between these two extremes would see activity between the listed figures.