ASTRAEA was the fifth minor planet to be discovered some 38-years Vesta. It was accidentally found by Karl Ludwig Hencke while looking for 4 Vesta on 08th December 1845 - who two months later also found 6 Hebe.
ASTRAEA DATADiscoverer : Karl Ludwig Hencke Date : 08 December 8, 1845 Satellites : 0 Diameter : 167×123×82 km. Polar Tilt : 29.56° Period (P) : 4.13 years Synodic Period : 453.69 days Orbital Velocity : 18.39 km.s-1 Perihelion (q) : 2.077 A.U. Aphelion (Q) : 3.070 A.U. Eccentricity (e) : 0.193 Inclination (i) : 5.369° Mass : 2.4×1018 kg. Mean Density : 2.7 g.cm-3 Mean Distance : 2.776 AU or 4.157×108 km Sidereal Rotation : 16.801 hr. Mean Sidereal Rotation : 0.7000 d. Maximum Diameter : 0.144″ (arcsec) Minimum Diameter : 0.040″ (arcsec) Maximum Magnitude : 9.0 Minimum Magnitude : 12.9 |
In ancient Greek mythology, Astraea or Astræa was one of the most important and endearing of the goddesses, being the embodiment of justice. She is known as the star maiden in some mythologies, being the daughter of either Zeus and Themis, or in alternative mythologies, of Eos (Aurora) and Astraeus. According to Robert Graves in “The Greek Myths”, Astraea was the last of the immortal gods to reside on the Earth before moving towards the Heavens thus ending the Greek’s so-called “Golden Age” and the rise of human society. Her justice, and impartiality towards the law, is often associated with the French and the America versions of the “Statue of Liberty.” For astronomers she is the closest of the goddess that is related to the stars. [ Perhaps Astraea should be worshipped, or to make a suitable sacrifice, by all amateur astronomers to request her kind influence and remove those often pesky clouds that sometimes hide her sparkling celestial lights! ]
At the mean distance of 2.573 A.U. or 385 million kilometres, Astraea takes 4.13 years to orbit the Sun. During favourable oppositions, Astraea can be as close to the Earth as 1.08 A.U or receed to the maximum distance - opposite to the Sun - being 4.07 A.U. Astraea orbit is well established, though small positional changes are known, being due to perturbations from mainly Ceres, Pallas and Vesta. The mean magnitude is 10.9, and this may vary between 9.0 and 12.9. Unfortunately, general visibility in binoculars is often restricted to just for a few months either side of favourable oppositions. At other times, including unfavourable apparitions, a small to medium telescopes are required to see this minor planet. The orbit is inclined at 5.4° to the ecliptic, and so, much of the time follows the same paths along the major planets as do the major planets.
Compared to the four main asteroids, once considered as real planets, Astraea is quite small, whose odd shaped dimensions are 167×123×82 kilometres - suggesting the asteroid is twice as long as it is wide. From Earth, the diameter can vary between 0.041 and 0.066 arc seconds - all too small for resolution by amateur telescopes. Telescopically, Astraea appears as yellow ‘star’. Observations of the slight changes in brightness iscaused mainly by its odd shape - suggesting the rotation period of 16 hours 48 minutes. For its size, Astraea is reasonably reflective compared to other asteroids, being classed as an S-type asteroid and having an albedo of 0.227. It is thought this asteroid is composed of mainly heavy silicates that also includes metals like nickel and iron.
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0h UT (J2000) Mag Δ r El. Con
DATE R.A. Decl. V A.U. A.U. o
hh mm.m o ′
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12 Jan 13 04.2 -03 45 11.0 1.800 2.123 095 Vir
26 Jan 13 19.7 -04 24 10.8 1.654 2.138 105 Vir
09 Feb 13 29.1 -04 28 10.6 1.518 2.156 117 Vir
23 Feb 13 33.9 -03 53 10.3 1.400 2.175 130 Vir
08 Mar 13 32.0 -02 41 10.0 1.309 2.197 145 Vir
22 Mar 13 24.8 -01 03 09.7 1.255 2.219 160 Vir
05 Apr 13 14.3 -00 40 09.4 1.248 2.243 172 Vir
19 Apr 13 02.5 +02 04 09.7 1.291 2.269 162 Vir
03 May 12 54.8 +02 50 10.1 1.380 2.295 148 Vir
17 May 12 50.8 +02 52 10.5 1.507 2.322 134 Vir
31 May 12 51.7 +02 15 10.9 1.663 2.350 121 Vir
14 Jun 12 57.7 +01 06 11.2 1.840 2.379 109 Vir
28 Jun 13 07.2 -00 26 11.4 2.029 2.408 099 Vir
12 Jul 13 20.6 -02 13 11.7 2.225 2.437 089 Vir
26 Jul 13 36.7 -04 10 11.9 2.422 2.466 080 Vir
09 Aug 13 53.1 -06 11 12.0 2.617 2.496 072 Vir
23 Aug 14 12.7 -08 14 12.1 2.806 2.525 064 Vir
06 Sep 14 33.3 -10 14 12.2 2.985 2.554 056 Lib
20 Sep 14 54.7 -12 09 12.3 3.152 2.583 048 Lib
04 Oct 15 17.7 -13 55 12.3 3.302 2.612 040 Lib
18 Oct 15 40.3 -15 31 12.3 3.434 2.640 032 Lib
01 Nov 16 04.1 -16 55 12.3 3.545 2.667 024 Sco
15 Nov 16 29.0 -18 04 12.3 3.632 2.694 016 Oph
29 Nov 16 54.7 -18 59 12.2 3.694 2.721 008 Oph
13 Dec 17 19.0 -19 37 12.1 3.728 2.746 004 Oph
27 Dec 17 43.6 -19 58 12.3 3.735 2.771 010 Oph
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Astraea is well placed for all obsevers in both hemispheres for the first half of the year. 2008 finds this asteroid rising in brightness in the constellation of Virgo where it will remain until the end of August. On April 5th opposition is reached where the magnitude peaks at 9.4 magnitude - easily visible in binoculars in a dark sky.
On 27th February, Astraea will be stationary, before moving backwards back into central Virgo in retrograde motion. Telescopically, on the 09th March, this asteroid will be in the same field as the Holden triple star, HLD 15, placed some 16 arcmin to the northeast. The primary of this star is an orange K0 7.9 magnitude star, which has the 12.1 magnitude companion some 16 arcsec towards the west at PA 295°. There is also another slightly brighter companion further on in the same direction, that is 2.3 arcmin west of the primary. Both will be easily seen in 15cm or 2 cm telescopes, and with care in 10.5cm in dark skies.
Near maximum brightness, on 15th March Astraea will make its closest approach to the 3.4 magnitude star ζ Virginis / Heze, being 1.8° NE away. This will make the asteroid very easy to identify. However, another close approach occurs on 21st March at 10:36 pm, when Astraea passes within 1.5 arcmin from 6.0 magnitude HIP 65545, that will be sadly be best seen from the Indian Ocean, or from Sri Lanka and India itelf. However, South-Eastern Australians will be able to see Astraea just before sunrise towards the eastern horizon some 3 arcmin south of this same star.
Watch out for Astraea on 4th May, as the 10th asteroid passes the star δ Virginis / Auva which lies 25 arcmin north. The telescopic field will also show the star HIP 63056 7.0 magnitude some 13′ NE. Again on the 12th May, this asteroid will lie close and 8′ southwards of 6th magnitude, 37 Vir, where it will stay close to for several days. By 16th, 10.5 magnitude Astraea will again be stationary, before resuming it direct motion across the sky.
After about September the fainter magnitude makes Astraea fairly dim and uninteresting in the evening sky. Solar conjunction occurs on 11th December. During all of 2009 the apparition of this minor planet will be disappointing, and it will not be as bright as 10th magnitude again until mid-March 2012.
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0h UT (J2000) Mag Δ r El. Con
DATE R.A. Decl. V A.U. A.U. o
hh mm.m o ′
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10 Jan 18 08.3 -20 04 12.4 3.712 2.796 018 Sgr
24 Jan 18 31.6 -19 55 12.5 3.662 2.819 027 Sgr
07 Feb 18 54.4 -19 33 12.6 3.584 2.841 036 Sgr
21 Feb 19 15.3 -18 59 12.6 3.480 2.863 045 Sgr
07 Mar 19 36.0 -18 18 12.7 3.353 2.883 054 Sgr
21 Mar 19 53.0 -17 31 12.6 3.205 2.903 064 Sgr
04 Apr 20 09.0 -16 44 12.6 3.042 2.922 074 Cap
18 Apr 20 22.3 -15 59 12.5 2.867 2.939 084 Cap
02 May 20 31.5 -15 21 12.4 2.688 2.956 095 Cap
16 May 20 38.2 -14 55 12.2 2.511 2.971 107 Cap
30 May 20 40.4 -14 46 12.0 2.346 2.986 120 Cap
13 Jun 20 38.9 -14 57 11.8 2.203 2.999 134 Cap
27 Jun 20 31.4 -15 28 11.5 2.094 3.011 149 Cap
11 Jul 20 20.2 -16 17 11.2 2.029 3.022 165 Cap
25 Jul 20 08.6 -17 14 11.0 2.017 3.032 177 Cap
08 Aug 19 56.1 -18 12 11.3 2.061 3.041 162 Sgr
22 Aug 19 46.3 -19 03 11.6 2.157 3.048 146 Sgr
05 Sep 19 41.1 -19 41 11.9 2.296 3.055 131 Sgr
19 Sep 19 40.8 -20 06 12.1 2.467 3.060 117 Sgr
03 Oct 19 45.0 -20 18 12.4 2.659 3.064 104 Sgr
17 Oct 19 51.8 -20 16 12.5 2.861 3.067 092 Sgr
31 Oct 20 02.6 -20 01 12.7 3.063 3.069 081 Sgr
14 Nov 20 16.1 -19 32 12.8 3.260 3.070 070 Cap
28 Nov 20 32.6 -18 50 12.8 3.443 3.069 060 Cap
12 Dec 20 50.9 -17 56 12.9 3.607 3.067 050 Cap
26 Dec 21 08.6 -16 49 12.9 3.749 3.065 040 Cap
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During all of 2009 the apparition of this minor planet will be disappointing, and it will not be as bright as 10th magnitude again until mid-March 2012.
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0h UT (J2000) Mag Δ r El. Con
DATE R.A. Decl. V A.U. A.U. o
hh mm.m o ′
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09 Jan 21 27.6 -15 30 12.8 3.864 3.061 031 Cap
23 Jan 21 47.7 -14 02 12.8 3.950 3.055 022 Cap
06 Feb 22 07.6 -12 26 12.7 4.005 3.049 012 Aqr
20 Feb 22 27.3 -10 42 12.5 4.028 3.042 004 Aqr
06 Mar 22 47.8 -08 54 12.5 4.019 3.033 005 Aqr
20 Mar 23 07.8 -07 04 12.7 3.979 3.023 014 Aqr
03 Apr 23 26.2 -05 13 12.7 3.908 3.013 023 Aqr
17 Apr 23 46.0 -03 23 12.8 3.810 3.001 032 Aqr
01 May 00 04.9 -01 37 12.8 3.685 2.988 040 Psc
15 May 00 21.8 +00 02 12.8 3.536 2.973 049 Psc
29 May 00 38.2 +01 33 12.7 3.367 2.958 058 Cet
12 Jun 00 54.8 +02 54 12.7 3.182 2.942 067 Psc
26 Jun 01 10.0 +04 00 12.6 2.983 2.925 077 Psc
10 Jul 01 21.2 +04 50 12.4 2.777 2.906 087 Psc
24 Jul 01 31.6 +05 21 12.2 2.569 2.887 098 Psc
07 Aug 01 39.6 +05 29 12.0 2.366 2.867 109 Psc
21 Aug 01 42.1 +05 11 11.7 2.176 2.846 122 Psc
04 Sep 01 41.6 +04 25 11.4 2.010 2.824 136 Psc
18 Sep 01 36.7 +03 15 11.1 1.879 2.801 151 Psc
02 Oct 01 26.1 +01 47 10.8 1.794 2.777 166 Cet
16 Oct 01 14.2 +00 16 10.6 1.763 2.752 171 Cet
30 Oct 01 03.7 -01 00 10.9 1.787 2.727 157 Cet
13 Nov 00 54.1 -01 46 11.1 1.861 2.701 141 Cet
27 Nov 00 49.2 -01 55 11.4 1.975 2.674 126 Cet
11 Dec 00 50.4 -01 28 11.6 2.116 2.647 112 Cet
25 Dec 00 55.1 -00 30 11.8 2.273 2.619 099 Cet
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0h UT (J2000) Mag Δ r El. Con
DATE R.A. Decl. V A.U. A.U. o
hh mm.m o ′
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08 Jan 01 04.7 +00 51 11.9 2.435 2.591 088 Cet
22 Jan 01 17.7 +02 31 12.0 2.594 2.563 077 Cet
05 Feb 01 32.7 +04 24 12.1 2.745 2.534 067 Psc
19 Feb 01 50.6 +06 25 12.1 2.882 2.505 058 Psc
05 Mar 02 11.0 +08 29 12.1 3.003 2.476 049 Cet
19 Mar 02 32.9 +10 33 12.1 3.104 2.447 041 Ari
02 Apr 02 55.0 +12 32 12.1 3.186 2.418 034 Ari
16 Apr 03 20.4 +14 25 12.0 3.248 2.389 026 Ari
30 Apr 03 47.8 +16 06 11.9 3.289 2.361 019 Tau
14 May 04 14.1 +17 34 11.7 3.309 2.333 013 Tau
28 May 04 42.1 +18 46 11.6 3.310 2.306 006 Tau
11 Jun 05 12.6 +19 39 11.4 3.292 2.280 003 Tau
25 Jun 05 42.3 +20 11 11.5 3.256 2.254 008 Tau
09 Jul 06 12.1 +20 21 11.6 3.204 2.230 014 Ori
23 Jul 06 43.5 +20 08 11.7 3.136 2.207 020 Gem
06 Aug 07 14.5 +19 33 11.7 3.053 2.186 026 Gem
20 Aug 07 44.8 +18 37 11.7 2.956 2.166 032 Gem
03 Sep 08 14.2 +17 22 11.7 2.847 2.148 038 Cnc
17 Sep 08 43.6 +15 49 11.7 2.726 2.132 045 Cnc
01 Oct 09 12.6 +14 04 11.6 2.595 2.118 051 Cnc
15 Oct 09 39.2 +12 09 11.5 2.455 2.107 058 Leo
29 Oct 10 05.9 +10 09 11.4 2.307 2.097 065 Leo
12 Nov 10 30.2 +08 11 11.3 2.152 2.090 073 Leo
26 Nov 10 52.6 +06 20 11.2 1.994 2.086 081 Leo
10 Dec 11 13.2 +04 43 11.0 1.834 2.084 090 Leo
24 Dec 11 30.0 +03 29 10.8 1.676 2.085 100 Leo
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0h UT (J2000) Mag Δ r El. Con
DATE R.A. Decl. V A.U. A.U. o
hh mm.m o ′
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07 Jan 11 44.1 +02 44 10.6 1.525 2.088 111 Vir
21 Jan 11 53.1 +02 39 10.3 1.388 2.093 123 Vir
04 Feb 11 56.9 +03 18 09.9 1.272 2.101 137 Vir
18 Feb 11 53.1 +04 41 09.6 1.188 2.112 152 Vir
03 Mar 11 44.4 +06 35 09.2 1.145 2.124 168 Vir
17 Mar 11 34.8 +08 32 09.2 1.150 2.139 172 Leo
31 Mar 11 24.6 +10 04 09.6 1.203 2.156 157 Leo
14 Apr 11 18.7 +10 52 10.0 1.299 2.175 141 Leo
28 Apr 11 18.3 +10 53 10.4 1.429 2.195 128 Leo
12 May 11 23.4 +10 12 10.7 1.582 2.217 116 Leo
26 May 11 33.3 +08 59 11.0 1.753 2.241 105 Leo
09 Jun 11 46.2 +07 20 11.3 1.933 2.266 095 Vir
23 Jun 12 02.6 +05 24 11.5 2.118 2.291 086 Vir
07 Jul 12 20.3 +03 14 11.7 2.303 2.318 078 Vir
21 Jul 12 39.9 +00 57 11.8 2.487 2.345 070 Vir
04 Aug 13 00.4 -01 26 11.9 2.665 2.373 062 Vir
18 Aug 13 21.7 -03 49 12.0 2.835 2.402 055 Vir
01 Sep 13 44.6 -06 11 12.1 2.994 2.431 048 Vir
15 Sep 14 07.0 -08 27 12.1 3.140 2.460 040 Vir
29 Sep 14 31.0 -10 36 12.2 3.270 2.489 033 Lib
13 Oct 14 56.3 -12 36 12.1 3.382 2.518 026 Lib
27 Oct 15 21.9 -14 24 12.1 3.473 2.547 018 Lib
10 Nov 15 46.5 -15 57 12.0 3.542 2.576 011 Lib
24 Nov 16 11.9 -17 16 11.9 3.588 2.604 004 Sco
08 Dec 16 37.9 -18 18 12.0 3.607 2.632 007 Oph
22 Dec 17 02.2 -19 02 12.2 3.601 2.660 015 Oph
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0h UT (J2000) Mag Δ r El. Con
DATE R.A. Decl. V A.U. A.U. o
hh mm.m o ′
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05 Jan 17 27.4 -19 30 12.3 3.567 2.687 023 Oph
19 Jan 17 52.3 -19 41 12.4 3.507 2.713 031 Sgr
02 Feb 18 15.4 -19 37 12.5 3.422 2.739 040 Sgr
16 Feb 18 37.5 -19 20 12.5 3.313 2.764 049 Sgr
02 Mar 18 57.2 -18 52 12.5 3.183 2.788 058 Sgr
16 Mar 19 15.8 -18 18 12.5 3.034 2.811 068 Sgr
30 Mar 19 32.0 -17 40 12.4 2.872 2.834 078 Sgr
13 Apr 19 43.1 -17 02 12.3 2.701 2.856 088 Sgr
27 Apr 19 52.7 -16 30 12.2 2.529 2.876 100 Sgr
11 May 19 58.5 -16 08 12.0 2.361 2.896 112 Sgr
25 May 19 58.8 -16 01 11.8 2.210 2.915 125 Sgr
08 Jun 19 54.9 -16 10 11.5 2.084 2.933 140 Sgr
22 Jun 19 45.9 -16 37 11.3 1.997 2.949 155 Sgr
06 Jul 19 33.2 -17 17 11.0 1.957 2.965 171 Sgr
20 Jul 19 20.0 -18 04 11.0 1.972 2.979 171 Sgr
03 Aug 19 09.5 -18 50 11.4 2.041 2.993 155 Sgr
17 Aug 19 01.6 -19 31 11.7 2.158 3.005 140 Sgr
31 Aug 18 57.3 -20 05 11.9 2.314 3.017 126 Sgr
14 Sep 18 58.7 -20 30 12.2 2.498 3.027 112 Sgr
28 Sep 19 04.3 -20 45 12.4 2.697 3.036 100 Sgr
12 Oct 19 13.3 -20 50 12.6 2.904 3.043 088 Sgr
26 Oct 19 26.3 -20 45 12.7 3.109 3.050 077 Sgr
09 Nov 19 41.6 -20 27 12.8 3.306 3.056 067 Sgr
23 Nov 19 58.9 -19 57 12.9 3.487 3.060 057 Sgr
07 Dec 20 16.9 -19 14 12.9 3.650 3.063 047 Cap
21 Dec 20 35.2 -18 19 12.9 3.788 3.065 037 Cap
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0h UT (J2000) Mag Δ r El. Con
DATE R.A. Decl. V A.U. A.U. o
hh mm.m o ′
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04 Jan 20 55.7 -17 12 12.8 3.899 3.066 028 Cap
18 Jan 21 16.0 -15 55 12.8 3.981 3.066 019 Cap
01 Feb 21 36.1 -14 28 12.6 4.031 3.064 010 Cap
15 Feb 21 57.9 -12 54 12.4 4.049 3.061 001 Cap
01 Mar 22 17.2 -11 14 12.6 4.035 3.057 008 Aqr
15 Mar 22 36.8 -09 31 12.7 3.989 3.052 017 Aqr
29 Mar 22 56.8 -07 46 12.8 3.913 3.046 026 Aqr
12 Apr 23 14.9 -06 02 12.9 3.808 3.039 035 Aqr
26 Apr 23 32.8 -04 21 12.9 3.677 3.030 044 Aqr
10 May 23 49.5 -02 46 12.8 3.523 3.021 053 Psc
24 May 00 05.4 -01 19 12.8 3.350 3.010 062 Psc
07 Jun 00 20.2 -00 04 12.7 3.160 2.998 072 Psc
21 Jun 00 33.3 +00 58 12.6 2.960 2.985 082 Cet
05 Jul 00 44.1 +01 42 12.4 2.754 2.971 092 Cet
19 Jul 00 52.9 +02 04 12.2 2.549 2.955 103 Cet
02 Aug 00 57.4 +02 02 12.0 2.353 2.939 116 Cet
16 Aug 00 57.7 +01 32 11.7 2.176 2.922 129 Cet
30 Aug 00 54.9 +00 33 11.4 2.028 2.903 144 Cet
13 Sep 00 46.2 -00 49 11.1 1.922 2.884 159 Cet
27 Sep 00 36.0 -02 24 10.8 1.866 2.864 173 Cet
11 Oct 00 24.2 -03 54 10.9 1.866 2.842 165 Psc
25 Oct 00 13.9 -05 03 11.2 1.920 2.820 149 Psc
08 Nov 00 07.3 -05 39 11.4 2.020 2.797 134 Psc
22 Nov 00 04.0 -05 40 11.7 2.155 2.773 119 Psc
06 Dec 00 07.0 -05 07 11.9 2.311 2.748 106 Psc
20 Dec 00 14.4 -04 06 12.0 2.479 2.723 094 Psc
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************************ Opposition Conjunction ************************ 02 Aug 2005 06 Mar 2006 24 Oct 2006 02 Jul 2007 05 Apr 2008 11 Dec 2008 23 Jul 2009 25 Feb 2010 11 Oct 2010 09 Jun 2011 13 Mar 2012 28 Nov 2012 13 Jul 2013 16 Feb 2014 29 Sep 2014 20 May 2015 17 Feb 2016 13 Nov 2016 02 Jul 2017 29 Sep 2018 18 Sep 2019 06 Feb 2019 22 Jan 2020 28 Oct 2020 *************************
The user applying this data for any purpose forgoes any liability against the author. None of the information should be used for either legal or medical purposes. Although the data is accurate as possible some errors might be present. The onus of its use is place solely with the user.