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The Brighter Asteroids in 2011:     (4) Vesta

Charts showing the path of Vesta in 2011:     

27 January to 18 March 2011      8 March to 27 April 2011      27 April to December 2011

Vesta was at conjunction 2010 November 10 so is too close to the Sun for observation from early at the beginning of January 2011.

Positions of Vesta for 2011


Vesta during 2011

DAWN at Vesta

NASA's DAWN spacecraft entered orbit round Vesta on July 15/16 nearly 16000km from the asteroid. At this distance the 530km asteroid has an apparent diameter just under 2 degrees. This is nearly 4 times the apparent diameter of the full moon and about the size the Earth appears from the moon. DAWN's orbit will be lowered in the coming days. The spacecraft will stay in orbit round Vesta for a year before going onto Ceres, the largest asteroid, arriving there in February 2015. More details and a picture are on the NASA site.

Vesta from the Earth in 2011

Vesta is currently in Capricornus. It reaches opposition on August 5 when it will be magnitude 5.6, chart of Vesta's path in Capricornus.

Vesta will be a morning object moving through Sagittarius from mid January up to 2 April 2011 after which it moves into Capricornus until December when it enters Aquarius. It is stationary on June 24 after which it moves in a retrograde sense to the west until its second stationary position on 17 September when it resumes moving to the east.

Vesta is at opposition on August 5, when its magnitude will be 5.6. This will make it just visible to the unaided eye from a dark site on a moonless night - for those with sharp vision! It will of course be an easy binocular object

In the first half of the year, Vesta will principally be a morning object. By the beginning of July it will rise soon after 8pm NZST, so be reasonably easy to locate by 10 pm. During the first months of the year, Venus and Vesta will be moving on almost parallel paths. Venus will overtake the asteroid on February 9/10. In the morning sky on the 10th, Vesta and Venus will be just under half a degree apart, that is just less diameter of the full moon. A 4.86 magnitude star will be about a quarter degree from Vesta.

Vesta has a diameter of 530 km.   The orbital period is 3.63 years, its distance from the Sun varying between 2.15 and 2.57 AU, the orbit having an eccentricity if 0.09.   The orbit is inclined at 7.1° to the ecliptic. The opposition distance from the Earth varies between 1.14 AU and 1.57 AU.

Vesta's greatest distance from the Sun is only slightly more than Ceres' minimum distance.  Vesta is the brightest of the asteroids, at the best oppositions it does become a faint naked eye object.  It is the second largest asteroid, with a diameter just under 60% that of Ceres, but has a considerably lighter surface, reflecting some 42% of the light falling on it.  This, combined with Vesta's closer approach to the Sun, means Vesta is usually the brightest asteroid.

Vesta was the fourth Minor Planet or Asteroid to be discovered, being first observed as a minor planet in 1807 by H W Olbers at Bremen.   Because of its opposition brightness, it must, of course, have been seen naked eye many times before that, although as a faint star.


Chart showing the path of Vesta from late January to March 2011.

The chart also shows the path of Venus during February. Vesta and Venus are marked in their position for the morning of February 10 when they are closest. The 4.86 star is also shown. As seen through binoculars at about 6 am the sky will be rotated compared to the chart. Vesta will be to the left of, and slightly lower than Venus. The 4.86 star will be to the lower left of Vesta, at about the 7 o'clock position.

The chart is a southern hemisphere view with north at the bottom and east to the right. Stars to magnitude 9.5 are shown. Magnitudes are marked (without a decimal point) for stars brighter than 6.5. The circle on the chart represents a field of view 5° in diameter, a fairly typical field of view for binoculars.

Vesta, February and March 2011


Chart showing the path of Vesta during March and April 2011.

The chart is a southern hemisphere view with north at the bottom and east to the right. Stars to magnitude 9.5 are shown. Magnitudes are marked (without a decimal point) for stars brighter than 6.5. The circle on the chart represents a field of view 5° in diameter, a fairly typical field of view for binoculars.

Vesta, March and April 2011


Chart showing the path of Vesta from April to December 2011.

The chart shows includes the retrograde loop of Vesta either side of the time it is at opposition.

The chart is a southern hemisphere view with north at the bottom and east to the right. Stars to magnitude 8.5 are shown. Magnitudes are marked (without a decimal point) for stars brighter than 6.5. The circle on the chart represents a field of view 5° in diameter, a fairly typical field of view for binoculars.

Vesta, April to Decmber 2011

Charts prepared using GUIDE 8.0. Program produced by Project Pluto.


Positional data for Vesta during 2011.

Date
2011
R.A
hr min
Dec
 °  '
 Mag. Const
Jan 17 17 34.0 -20 18 7.8 Ophiuchus
Jan 27 17 56.1 -20 38 7.8 Sagittarius
Feb 6 18 17.9 -20 46 7.8 Sagittarius
Feb 16 18 39.3 -20 43 7.8 Sagittarius
Feb 26 19 00.2 -20 32 7.8 Sagittarius
Mar 8 19 20.4 -20 12 7.7 Sagittarius
Mar 18 19 39.7 -19 46 7.7 Sagittarius
Mar 28 19 58.1 -19 16 7.6 Sagittarius
Apr 7 20 15.5 -18 43 7.5 Capricornus
Apr 17 20 31.6 -18 10 7.5 Capricornus
Apr 27 20 46.3 -17 39 7.4 Capricornus
May 7 20 59.4 -17 14 7.2 Capricornus
May 17 21 10.7 -16 56 7.1 Capricornus
May 27 21 19.8 -16 50 6.9 Capricornus
Jun 6 21 26.6 -16 59 6.8 Capricornus
Jun 16 21 30.6 -17 24 6.6 Capricornus
Jun 26 21 31.6 -18 07 6.4 Capricornus
Jul 6 21 29.5 -19 08 6.2 Capricornus
Jul 16 21 24.3 -20 22 6.0 Capricornus
Jul 26 21 16.6 -21 44 5.8 Capricornus
Aug 5 21 07.5 -23 03 5.6 Capricornus
Aug 15 20 58.1 -24 12 5.8 Capricornus
Aug 25 20 50.0 -25 04 6.1 Capricornus
Sep 4 20 44.2 -25 36 6.3 Capricornus
Sep 14 20 41.5 -25 48 6.6 Capricornus
Sep 24 20 41.9 -25 43 6.8 Capricornus
Oct 4 20 45.5 -25 22 7.0 Capricornus
Oct 14 20 51.7 -24 49 7.2 Capricornus
Oct 24 21 00.4 -24 04 7.4 Capricornus
Nov 3 21 10.9 -23 09 7.5 Capricornus
Nov 13 21 23.0 -22 05 7.7 Capricornus
Nov 23 21 36.4 -20 53 7.8 Capricornus
Dec 3 21 50.7 -19 32 7.9 Capricornus
Dec 13 22 05.7 -18 04 8.0 Aquarius
Dec 23 22 21.3 -16 30 8.1 Aquarius
2012 Jan 2 22 37.3 -14 51 8.1 Aquarius

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