Astronomy Answers: Planetary Phenomena 2021

# Astronomy AnswersPlanetary Phenomena 2021

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The diagram below is explained further on the page for the year 2000.

For an explanation of the above pictures, see the page for the year 2000.

The last table on this page lists a number of noteworthy planetary phenomena during the listed year. The first column ("date") gives the date and hour, in the form year-month-dayThour in the Gregorian calendar, in Universal Time (UT). The second column ("pl") identifies the planet that shows the phenomenon:

pl Planet
Me Mercury
Ve Venus
Ma Mars
Ju Jupiter
Sa Saturn
Ur Uranus
Ne Neptune
Lu Moon

The third column ("*") provides the type of the phenomenon. The fourth column ("AU") shows the value (distance) in Astronomical Units, if applicable. The fifth column ("deg") gives the value of a relevant angle (declination $$δ$$, elongation $$E$$, conjunction spread $$σ$$, or ecliptic longitude $$λ$$) in degrees. Which angle it is for each phenomenon is shown below in column "?". Declinations and ecliptical longitudes are measured relative to the equinox of the date.

?
Explanation
p perigee
a apogee
+dδgreatest northern declination
dδgreatest southern declination
cλconjunction (with the Sun)
oλopposition (relative to the Sun)
eEgreatest elongation
xaλpassage through the ascending node (zero ecliptical latitude)
xdλpassage through the descending node (zero ecliptical latitude)
bσleast conjunction spread (Mercury - Saturn)
Bσleast conjunction spread (Mercury - Neptune)
sσgreatest conjunction spread (Mercury - Saturn)
Sσgreatest conjunction spread (Mercury - Neptune)
Vλbegin eastward (prograde) acceleration
Pgλstationary point: begin eastward (prograde) motion
vλbegin westward (retrograde) acceleration
Rgλstationary point: begin westward (retrograde) motion

The calculations for the planets are based on the VSOP87 model (type A) of Laskar, and the calculations for the Moon are based on the most detailed model from [Meeus]. One position per day was calculated for each celestial object. The hour of the day for each phenomenon was determined by interpolation.

date pl * AU deg
2021-01-01T16
**
S +139.55
2021-01-06T08 Me v +297.33
2021-01-09T03 Lu p 0.002456
2021-01-09T06 Lu v +244.31
2021-01-10T08 Lu xd +259.72
2021-01-11T18 Ve d −23.18
2021-01-11T20 Lu d −24.87
2021-01-12T02 Ur d +13.34
2021-01-12T17 Lu c +293.23
2021-01-13T18 Ur Pg +36.73
2021-01-14T07 Ve v +277.76
2021-01-15T23 Ve xa +279.83
2021-01-16T04
**
B +82.39
2021-01-21T01 Lu a 0.002703
2021-01-21T04 Lu V +40.76
2021-01-23T08 Sa v +304.32
2021-01-23T09 Sa a 10.97
2021-01-23T13 Me e +18.56
2021-01-23T15 Sa c +304.35
2021-01-23T21 Me xd +323.19
2021-01-24T09 Lu xa +79.13
2021-01-26T03 Lu +d +24.90
2021-01-27T14 Ju a 6.071
2021-01-28T07 Lu o +129.08
2021-01-28T13 Ju c +309.38
2021-01-29T11 Ju v +309.59
2021-01-30T03 Me Rg +326.50
2021-01-30T08
**
S +125.11
2021-02-02T06 Lu v +198.32
2021-02-03T00 Me +d −10.53
2021-02-03T07 Lu p 0.002474
2021-02-04T03
**
b +75.38
2021-02-06T12 Lu xd +258.18
2021-02-08T01 Me c +320.02
2021-02-08T03 Lu d −24.95
2021-02-08T14 Me V +319.36
2021-02-10T02 Me p 0.6472
2021-02-11T07 Lu c +323.27
2021-02-12T13
**
B +76.19
2021-02-17T22 Lu a 0.002704
2021-02-18T06 Lu V +49.18
2021-02-20T13 Me Pg +311.03
2021-02-20T13 Lu xa +76.76
2021-02-22T11 Lu +d +25.05
2021-02-26T20 Lu o +158.96
2021-02-27T05
**
S +124.92
2021-02-27T21 Me d −16.11
2021-03-01T06 Lu v +194.03
2021-03-01T17 Lu p 0.002443
2021-03-03T04 Me xa +316.26
2021-03-05T12 Lu xd +255.35
2021-03-05T21 Me e −27.26
2021-03-07T08 Lu d −25.16
2021-03-10T12 Ne c +350.64
2021-03-10T14 Ne v +350.65
2021-03-11T09 Ne a 30.92
2021-03-12T21
**
B +74.89
2021-03-12T22 Lu c +196.96
2021-03-17T16 Lu a 0.002709
2021-03-18T04 Lu V +56.56
2021-03-19T15 Lu xa +73.68
2021-03-21T20 Lu +d +25.30
2021-03-26T00 Ve o +6.12
2021-03-27T19
**
S +123.85
2021-03-28T06 Lu o +188.34
2021-03-29T10 Lu v +205.87
2021-03-29T18 Ve a 1.723
2021-03-29T18 Lu p 0.002408
2021-04-01T14 Lu xd +252.53
2021-04-03T14 Lu d −25.41
2021-04-10T01
**
B +78.51
2021-04-11T14 Lu c +22.41
2021-04-14T05 Lu a 0.002715
2021-04-14T19 Lu V +60.63
2021-04-15T01 Me a 1.337
2021-04-15T17 Lu xa +71.45
2021-04-18T03 Lu +d +25.54
2021-04-19T00 Me o +30.15
2021-04-21T21 Me xd +36.29
2021-04-21T22 Me v +36.39
2021-04-22T09 Ma +d +24.90
2021-04-25T21
**
S +135.79
2021-04-26T15 Lu o +217.12
2021-04-26T22 Lu v +221.82
2021-04-27T03 Lu p 0.002389
2021-04-28T21 Lu xd +251.02
2021-04-30T07 Ur c +40.69
2021-04-30T15 Ur v +40.71
2021-04-30T19 Ur a 20.76
2021-04-30T21 Lu d −25.60
2021-05-08T04
**
B +99.33
2021-05-09T03 Ve xd +60.69
2021-05-11T07 Lu c +51.31
2021-05-11T09 Lu a 0.002717
2021-05-11T18 Lu V +56.79
2021-05-12T22 Lu xa +70.71
2021-05-15T10 Lu +d +25.64
2021-05-16T20 Me e +21.89
2021-05-17T08 Me +d +25.25
2021-05-18T00 Sa +d −17.36
2021-05-22T20 Sa Rg +313.52
2021-05-24T06
**
S +161.06
2021-05-25T12 Lu v +238.67
2021-05-25T13 Lu p 0.002388
2021-05-25T23 Lu o +245.42
2021-05-26T07 Lu xd +250.70
2021-05-28T07 Lu d −25.64
2021-05-29T10 Me Rg +84.72
2021-05-30T04 Me xa +84.69
2021-06-04T23 Ve +d +24.43
2021-06-05T17
**
B +119.37
2021-06-07T11 Lu V +50.58
2021-06-07T14 Lu a 0.002715
2021-06-09T04 Lu xa +70.79
2021-06-09T22 Lu c +79.79
2021-06-09T22 Me p 0.5504
2021-06-10T10 Me V +80.43
2021-06-10T13 Me c +80.36
2021-06-11T15 Lu +d +25.64
2021-06-16T08 Ju +d −11.58
2021-06-20T02 Ju Rg +332.19
2021-06-20T23
**
S +181.54
2021-06-21T16 Ne +d −3.73
2021-06-21T17 Me d +18.26
2021-06-22T09 Me Pg +76.13
2021-06-22T18 Lu xd +250.74
2021-06-22T21 Lu p 0.002406
2021-06-23T00 Lu v +254.78
2021-06-24T06 Lu o +273.50
2021-06-24T17 Lu d −25.63
2021-06-25T01 Ne Rg +353.20
2021-07-02T14
**
B +139.33
2021-07-04T16 Me e −21.34
2021-07-04T22 Lu V +52.82
2021-07-05T03 Lu a 0.002709
2021-07-06T10 Lu xa +70.49
2021-07-08T21 Lu +d +25.61
2021-07-09T13 Lu c +108.05
2021-07-18T20 Me xd +102.46
2021-07-18T23
**
S +232.43
2021-07-19T11 Me +d +22.86
2021-07-20T01 Lu xd +249.78
2021-07-20T22 Lu p 0.002437
2021-07-21T06 Lu v +267.71
2021-07-22T03 Lu d −25.64
2021-07-23T14 Lu o +301.42
2021-07-24T00
**
s +212.48
2021-07-28T12 Me v +122.04
2021-07-29T07
**
B +183.13
2021-07-31T23 Me o +129.37
2021-08-01T17 Lu V +58.36
2021-08-01T18 Sa o +310.19
2021-08-01T19 Lu a 0.002703
2021-08-01T23 Sa p 8.935
2021-08-02T00 Sa V +310.17
2021-08-02T14 Lu xa +68.92
2021-08-05T00 Me a 1.350
2021-08-05T04 Lu +d +25.69
2021-08-08T01 Lu c +136.23
2021-08-12T10
**
S +260.81
2021-08-16T04 Lu xd +247.57
2021-08-16T20 Lu p 0.002467
2021-08-17T14 Lu v +267.90
2021-08-18T10 Lu d −25.76
2021-08-18T13 Ur +d +15.88
2021-08-19T09 Ju V +327.24
2021-08-19T10 Ur Rg +44.80
2021-08-19T12 Ju o +327.23
2021-08-19T17 Ju p 4.013
2021-08-21T18
**
B +212.51
2021-08-22T00 Lu o +329.61
2021-08-26T03 Me xa +174.76
2021-08-28T16 Ve xa +195.29
2021-08-29T14 Lu a 0.002701
2021-08-29T15 Lu V +65.11
2021-08-29T17 Lu xa +66.17
2021-09-01T12 Lu +d +25.87
2021-09-01T12
**
S +346.98
2021-09-06T12 Lu c +164.62
2021-09-10T05 Lu v +216.70
2021-09-10T22 Lu p 0.002463
2021-09-12T04 Lu xd +244.73
2021-09-13T00 Ne p 28.92
2021-09-13T09 Me e +26.64
2021-09-13T12 Ne V +351.80
2021-09-13T21 Ne o +351.79
2021-09-14T15 Lu d −25.98
2021-09-16T02
**
B +165.96
2021-09-19T23 Ma a 2.638
2021-09-20T11 Lu o +358.22
2021-09-25T19 Lu xa +63.43
2021-09-26T09 Lu a 0.002705
2021-09-26T13 Lu V +72.23
2021-09-26T16 Me Rg +205.48
2021-09-26T21 Me d −13.35
2021-09-28T20 Lu +d +26.11
2021-09-28T23
**
S +218.08
2021-10-05T18
**
b +114.57
2021-10-05T23 Lu c +193.42
2021-10-07T08 Me p 0.6584
2021-10-07T16 Ma c +195.12
2021-10-07T21 Lu v +221.86
2021-10-08T05 Lu p 0.002429
2021-10-08T16 Me V +197.20
2021-10-09T04 Me c +196.60
2021-10-09T07 Lu xd +242.54
2021-10-10T11 Sa d −19.34
2021-10-10T13 Sa Pg +306.88
2021-10-11T21 Lu d −26.20
2021-10-12T18
**
B +148.50
2021-10-14T05
**
s +115.48
2021-10-14T20 Me xd +191.15
2021-10-15T20 Ju d −15.15
2021-10-17T16 Ju Pg +322.33
2021-10-18T03 Me Pg +190.13
2021-10-20T03 Lu o +27.44
2021-10-20T13 Me +d −2.88
2021-10-22T23 Lu xa +61.89
2021-10-24T03 Lu a 0.002711
2021-10-24T09 Lu V +78.25
2021-10-24T16 Me e −18.29
2021-10-26T04 Lu +d +26.29
2021-10-26T15
**
S +196.14
2021-10-29T02 Ve e +46.93
2021-11-04T03 Ur p 18.74
2021-11-04T09 Lu c +222.70
2021-11-04T10 Ur V +42.79
2021-11-04T11 Ur o +42.78
2021-11-05T07 Lu v +236.80
2021-11-05T10 Lu p 0.002399
2021-11-05T15 Lu xd +241.73
2021-11-06T03 Ve d −27.24
2021-11-08T04 Lu d −26.32
2021-11-10T13
**
B +123.21
2021-11-11T09 Me v +219.61
2021-11-18T21 Lu o +57.25
2021-11-19T05 Lu xa +61.69
2021-11-20T13 Lu a 0.002716
2021-11-20T16 Lu V +78.71
2021-11-22T02 Me xa +236.78
2021-11-22T10 Lu +d +26.34
2021-11-23T16
**
S +157.81
2021-11-28T19 Ne d −4.86
2021-11-29T00 Me o +247.67
2021-11-30T02 Me a 1.451
2021-11-30T21 Ne Pg +350.41
2021-12-03T02 Lu xd +241.72
2021-12-03T19 Lu c +252.40
2021-12-03T22 Lu p 0.002385
2021-12-03T23 Lu v +255.02
2021-12-05T14 Lu d −26.33
2021-12-05T15 Me V +258.10
2021-12-08T08
**
B +96.63
2021-12-15T14 Me d −25.44
2021-12-16T12 Lu xa +61.70
2021-12-16T22 Me v +275.84
2021-12-17T02 Lu V +68.94
2021-12-17T14 Lu a 0.002716
2021-12-18T16 Lu o +87.48
2021-12-18T22 Ve Rg +296.49
2021-12-19T04 Ma xa +244.42
2021-12-19T16 Lu +d +26.30
2021-12-19T19 Ve xd +296.47
2021-12-22T04
**
S +134.21
2021-12-30T13 Lu xd +241.23

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Last updated: 2021-07-19