อุกาบาต 2012-DA14 จะเฉียดโลกวันที่ 15 กพ. 2013 ห่างโลกแค่ 17,000 ไมล์ & update 5 กพ.ฝนอุกาบาตถล่มรัสเซีย

แปลคร่าวๆ แล้วจ้า ไปนอนก่อนน๊า.......:boo:

 

ภาพที่แสดง แปลมาจาก ที่นาซ่าให้ข้อมูลมา จุดที่จะมาใกล้โลกที่สุดคือ พิกัดตรงนั้น และคุณลักษณะต่างๆ ก็ที่เขียนไว้ เท่าที่นาซ่าคาด มันจะไม่เข้ามามีอันตรายต่อโลกจ้า

 

NASA agrees with the Russian Space Agency that there is no danger posed by the asteroid next week, stating that its trajectory has been accurately predicted and "it is therefore known that there is no chance that the asteroid might be on a collision course with Earth".

2012 DA14: Too close for comfort - English pravda.ru

นาซ่าเห็นด้วยกับ องค์การอวกาศรัสเซีย ที่ว่าจะไม่มีอันตรายจากอุกาบาตอาทิตย์หน้า เพราะวงโคจรมันได้ถูกคาดไว้อย่างแน่นอน ว่าไม่มีโอกาสที่อุกาบาตนี้จะมาชนโลก

 

Too close to home: Picture shows the predicted orbit of asteroid 2012 DA 14

Read more: Asteroid 2012 DA14 in 'near miss' with the Earth, will pass within 17,000 miles from earth on Friday | Mail Online
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http://echo.jpl.nasa.gov/asteroids/2012DA14/2012DA14_planning.html

Background


ASTROMETRY IS URGENTLY NEEDED


2012 DA14 was discovered by the La Sagra Sky Survey in Spain on February 23, 2012.
This object will make an extremely close approach to within 0.00023 AU of the center of Earth at
19:24 UT (11:24 AM PST) on February 15, 2013. That is only 0.09 lunar distances or 5.4 Earth
radii from the center of the Earth. The close approach will be about 27700 km above Earth's
surface. That's inside the distance to geosynchronous satellites but thousands of kilometers
above the elevation for low-Earth-orbit spacecraft such as the International Space Station.
At the time of closest approach, the asteroid will move about 0.8 degrees per minute.

This is the closest flyby by something this large that has ever been identified in advance.

The uncertainties in plane-of-sky position, Doppler frequency, and time delay will grow dramatically
during the approach, but even so, this object cannot impact Earth during this encounter.

2012 DA14's absolute magnitude of 24.4 suggests a diameter within a factor of two of about 50 meters.
Nick Moskovitz (MIT) reported that he obtained lightcurves and
spectroscopy shortly after 2012 DA14 was discovered. The asteroid has a rotation period of about 6 hours
and it's an L-class object, hinting that it has an optical albedo of about 0.2. The lightcurve
amplitude is close to one magnitude, so the shape is probably elongated. Nothing else is known
about this object.

Due to the extremely close approach, this object will be a very strong radar target at Goldstone
and we plan to image it with the highest resolution available (3.75 meters) from the chirp system.
The round-trip time on the first track on Feb. 16 is so short that observations on that day
will be bistatic with reception of radar echoes at DSS-13. The images should provide constraints
on the size, shape, and rotation state of the object, but 2012 DA14 is so small that the images are
unlikely to reveal fine-scale features on the surface.

2012 DA14 will approach from the south and will enter Goldstone's declination window on February 16, 2013,
shortly after the closest approach. Afterward it will be a circumpolar object as it recedes from Earth.

Radar observations at Goldstone are scheduled on 2013 Feb. 16, 18, 19, and 20.

We need additional astrometry to improve the orbit. As a result, below we list circumstances for optical
observations starting many months before the encounter in order to help facilitate observations
by optical observers. The apparent magnitudes will be fainter than 22nd until until the beginning of
February, but the solar elongation will be only about 60 degrees, so obtaining optical astrometry
will be challenging. In addition, the asteroid will be at far southern declinations until Feb. 15
when it will move from about -75 deg to +75 deg in only a few hours.

This object will not be observable at Arecibo.

2012 DA14 will brighten to about 7th magnitude at the time of the closest approach, when observers
in Asia might be able to see it with binoculars and small telescopes. Doing so will require
knowing very precisely where to look and will require a site-specific ephemeris due to parallax.

2012 DA14 is too small to be classified as a "Potentially Hazardous Asteroid" (PHA) by the Minor
Planet Center.

Due to the very close flyby, the asteroid's orbit will change and its semimajor axis will shrink
to slightly less than 1 AU and its orbital period will also reduce to slightly less than 1 year.

The 2013 flyby is the closest over the entire time span that the motion can be computed reliably;
namely, the interval between 1851-2149.

Radar observations are also planned by other researchers at the EISCAT radar near Tromso, Norway
starting at 20:00 UT on Feb. 15 and at the Haystack Observatory in Massachusetts starting at 22:00 UT
on Feb. 15. Goldstone observations start at 03:00 UT on Feb. 16, several hours after observations
begin at the other radars.

Orbital and Physical Characteristics
orbit type Apollo
semimajor axis 1.002 AU
eccentricity 0.108
inclination 10.4 deg
perihelion distance 0.893 AU
aphelion distance 1.110 AU
absolute magnitude (H) 24.4
diameter ~50 meters (+- a factor of two)
rotation period ~6 h N. Moskovitz, pers. comm.
pole direction unknown
lightcurve amplitude ~1 mag N. Moskovitz, pers. comm.
spectral class Ld N. Moskovitz, pers. comm.

Last update: 2013 February 11