Astronomy Answers
Planetary Phenomena 2021


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

1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059 2060 2061 2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072 2073 2074 2075 2076 2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 2090 2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105

[2021] [Q 2021]

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
2021−01−01T19
** 
S +131.03
2021−01−06T20 Me v +297.33
2021−01−09T15 Lu p 0.002456
2021−01−09T18 Lu v +244.38
2021−01−10T20 Lu xd +259.73
2021−01−12T06 Ve d −23.18
2021−01−12T08 Lu d −24.87
2021−01−12T14 Ur d +13.34
2021−01−13T05 Lu c +293.24
2021−01−14T06 Ur Pg +36.73
2021−01−14T08 Pl v +294.64
2021−01−14T11 Pl o +294.65
2021−01−14T19 Ve v +277.76
2021−01−16T01
** 
B +81.46
2021−01−16T11 Ve xa +279.83
2021−01−17T00 Pl a 35.18
2021−01−21T13 Lu a 0.002703
2021−01−21T16 Lu V +40.72
2021−01−23T20 Sa v +304.32
2021−01−23T21 Sa a 10.97
2021−01−24T01 Me e +18.56
2021−01−24T03 Sa c +304.35
2021−01−24T09 Me xd +323.19
2021−01−24T21 Lu xa +79.14
2021−01−26T15 Lu +d +24.90
2021−01−28T02 Ju a 6.071
2021−01−28T19 Lu o +129.09
2021−01−29T01 Ju c +309.38
2021−01−29T23 Ju v +309.59
2021−01−30T09
** 
S +120.75
2021−01−30T15 Me Rg +326.50
2021−02−02T18 Lu v +198.44
2021−02−03T12 Me +d −10.53
2021−02−03T19 Lu p 0.002474
2021−02−04T15
** 
b +75.38
2021−02−07T00 Lu xd +258.19
2021−02−08T13 Me c +320.02
2021−02−08T15 Lu d −24.95
2021−02−09T02 Me V +319.36
2021−02−10T14 Me p 0.6472
2021−02−11T19 Lu c +323.28
2021−02−12T12
** 
B +77.48
2021−02−18T10 Lu a 0.002704
2021−02−18T18 Lu V +49.19
2021−02−21T00 Me Pg +311.03
2021−02−21T01 Lu xa +76.72
2021−02−22T23 Lu +d +25.06
2021−02−27T06
** 
S +121.79
2021−02−27T08 Lu o +158.97
2021−02−28T09 Me d −16.11
2021−03−01T18 Lu v +194.04
2021−03−02T05 Lu p 0.002443
2021−03−03T16 Me xa +316.26
2021−03−06T00 Lu xd +255.36
2021−03−06T09 Me e −27.26
2021−03−07T20 Lu d −25.16
2021−03−11T00 Ne c +350.64
2021−03−11T02 Ne v +350.65
2021−03−11T21 Ne a 30.92
2021−03−12T14
** 
B +79.21
2021−03−13T10 Lu c +196.97
2021−03−18T04 Lu a 0.002709
2021−03−18T16 Lu V +56.52
2021−03−20T03 Lu xa +73.64
2021−03−22T08 Lu +d +25.30
2021−03−26T12 Ve o +6.12
2021−03−27T19
** 
S +124.67
2021−03−28T18 Lu o +188.30
2021−03−29T23 Lu v +205.94
2021−03−30T06 Ve a 1.723
2021−03−30T06 Lu p 0.002408
2021−04−02T02 Lu xd +252.54
2021−04−04T02 Lu d −25.41
2021−04−04T21 Pl +d −22.15
2021−04−09T11
** 
B +87.16
2021−04−12T02 Lu c +22.42
2021−04−14T17 Lu a 0.002715
2021−04−15T07 Lu V +60.59
2021−04−15T13 Me a 1.337
2021−04−16T05 Lu xa +71.46
2021−04−18T15 Lu +d +25.54
2021−04−19T12 Me o +30.16
2021−04−22T09 Me xd +36.29
2021−04−22T10 Me v +36.39
2021−04−22T21 Ma +d +24.90
2021−04−25T18
** 
S +141.03
2021−04−27T03 Lu o +217.13
2021−04−27T11 Lu v +221.88
2021−04−27T14 Pl Rg +296.81
2021−04−27T15 Lu p 0.002389
2021−04−29T09 Lu xd +251.03
2021−04−30T19 Ur c +40.69
2021−05−01T03 Ur v +40.71
2021−05−01T07 Ur a 20.76
2021−05−01T09 Lu d −25.60
2021−05−07T09
** 
B +110.65
2021−05−09T15 Ve xd +60.69
2021−05−11T19 Lu c +51.32
2021−05−11T21 Lu a 0.002717
2021−05−12T06 Lu V +56.80
2021−05−13T10 Lu xa +70.72
2021−05−15T22 Lu +d +25.64
2021−05−17T08 Me e +21.89
2021−05−17T20 Me +d +25.25
2021−05−18T12 Sa +d −17.36
2021−05−23T08 Sa Rg +313.52
2021−05−23T20
** 
S +169.84
2021−05−26T00 Lu v +238.68
2021−05−26T01 Lu p 0.002388
2021−05−26T11 Lu o +245.43
2021−05−26T19 Lu xd +250.71
2021−05−28T19 Lu d −25.64
2021−05−29T22 Me Rg +84.72
2021−05−30T15 Me xa +84.69
2021−06−04T20
** 
B +132.28
2021−06−05T11 Ve +d +24.43
2021−06−07T23 Lu V +50.68
2021−06−08T02 Lu a 0.002715
2021−06−09T16 Lu xa +70.79
2021−06−10T10 Lu c +79.80
2021−06−10T10 Me p 0.5504
2021−06−10T22 Me V +80.42
2021−06−11T01 Me c +80.36
2021−06−12T03 Lu +d +25.64
2021−06−16T20 Ju +d −11.58
2021−06−20T05
** 
S +190.89
2021−06−20T14 Ju Rg +332.19
2021−06−22T04 Ne +d −3.73
2021−06−22T05 Me d +18.26
2021−06−22T21 Me Pg +76.13
2021−06−23T06 Lu xd +250.69
2021−06−23T09 Lu p 0.002406
2021−06−23T12 Lu v +254.79
2021−06−24T18 Lu o +273.45
2021−06−25T05 Lu d −25.63
2021−06−25T13 Ne Rg +353.20
2021−07−01T12
** 
B +150.35
2021−07−05T04 Me e −21.34
2021−07−05T10 Lu V +52.83
2021−07−05T15 Lu a 0.002709
2021−07−06T22 Lu xa +70.49
2021−07−09T09 Lu +d +25.61
2021−07−10T01 Lu c +108.05
2021−07−15T09 Pl p 33.30
2021−07−17T10
** 
S +238.48
2021−07−17T11 Pl V +295.57
2021−07−17T11 Pl c +295.57
2021−07−19T08 Me xd +102.46
2021−07−19T23 Me +d +22.86
2021−07−20T13 Lu xd +249.79
2021−07−21T10 Lu p 0.002437
2021−07−21T18 Lu v +267.77
2021−07−22T15 Lu d −25.64
2021−07−24T02 Lu o +301.43
2021−07−24T12
** 
s +212.48
2021−07−27T11
** 
B +187.05
2021−07−29T00 Me v +122.04
2021−08−01T11 Me o +129.38
2021−08−02T05 Lu V +58.37
2021−08−02T06 Sa o +310.19
2021−08−02T07 Lu a 0.002703
2021−08−02T11 Sa p 8.935
2021−08−02T12 Sa V +310.17
2021−08−03T02 Lu xa +68.93
2021−08−05T12 Me a 1.350
2021−08−05T16 Lu +d +25.69
2021−08−08T13 Lu c +136.24
2021−08−09T15
** 
S +331.69
2021−08−16T16 Lu xd +247.58
2021−08−17T08 Lu p 0.002468
2021−08−18T02 Lu v +267.91
2021−08−18T22 Lu d −25.76
2021−08−19T00 Ur +d +15.88
2021−08−19T21 Ju V +327.24
2021−08−19T22 Ur Rg +44.80
2021−08−20T00 Ju o +327.23
2021−08−20T05 Ju p 4.013
2021−08−21T11
** 
B +186.40
2021−08−22T12 Lu o +329.62
2021−08−26T15 Me xa +174.76
2021−08−29T04 Ve xa +195.29
2021−08−30T02 Lu a 0.002701
2021−08−30T03 Lu V +65.16
2021−08−30T05 Lu xa +66.18
2021−09−02T00 Lu +d +25.87
2021−09−02T01
** 
S +236.11
2021−09−07T00 Lu c +164.63
2021−09−10T17 Lu v +216.59
2021−09−11T10 Lu p 0.002463
2021−09−12T16 Lu xd +244.74
2021−09−13T12 Ne p 28.92
2021−09−13T21 Me e +26.64
2021−09−14T00 Ne V +351.80
2021−09−14T09 Ne o +351.79
2021−09−15T03 Lu d −25.98
2021−09−16T18
** 
B +150.52
2021−09−20T11 Ma a 2.638
2021−09−20T23 Lu o +358.23
2021−09−26T07 Lu xa +63.44
2021−09−26T21 Lu a 0.002705
2021−09−27T01 Lu V +72.20
2021−09−27T04 Me Rg +205.48
2021−09−27T09 Me d −13.35
2021−09−29T08 Lu +d +26.10
2021−09−29T15
** 
S +189.23
2021−10−06T06
** 
b +114.57
2021−10−06T11 Lu c +193.43
2021−10−06T12 Pl Pg +294.32
2021−10−07T20 Me p 0.6584
2021−10−08T04 Ma c +195.12
2021−10−08T09 Lu v +221.81
2021−10−08T17 Lu p 0.002429
2021−10−09T04 Me V +197.20
2021−10−09T16 Me c +196.60
2021−10−09T19 Lu xd +242.55
2021−10−10T23 Sa d −19.34
2021−10−11T01 Sa Pg +306.88
2021−10−12T09 Lu d −26.20
2021−10−13T09
** 
B +135.96
2021−10−13T23 Pl d −22.88
2021−10−14T17
** 
s +115.48
2021−10−15T08 Me xd +191.16
2021−10−16T08 Ju d −15.15
2021−10−18T04 Ju Pg +322.33
2021−10−18T15 Me Pg +190.13
2021−10−20T15 Lu o +27.45
2021−10−21T01 Me +d −2.88
2021−10−23T11 Lu xa +61.90
2021−10−24T15 Lu a 0.002711
2021−10−24T20 Lu V +78.17
2021−10−25T04 Me e −18.29
2021−10−26T16 Lu +d +26.29
2021−10−27T01
** 
S +173.84
2021−10−29T14 Ve e +46.93
2021−11−04T15 Ur p 18.74
2021−11−04T21 Lu c +222.70
2021−11−04T22 Ur V +42.79
2021−11−04T23 Ur o +42.78
2021−11−05T19 Lu v +236.81
2021−11−05T22 Lu p 0.002399
2021−11−06T03 Lu xd +241.74
2021−11−06T15 Ve d −27.24
2021−11−08T16 Lu d −26.32
2021−11−10T22
** 
B +114.09
2021−11−11T21 Me v +219.61
2021−11−19T08 Lu o +57.26
2021−11−19T17 Lu xa +61.70
2021−11−21T01 Lu a 0.002716
2021−11−21T04 Lu V +78.63
2021−11−22T14 Me xa +236.78
2021−11−22T22 Lu +d +26.34
2021−11−24T00
** 
S +144.06
2021−11−29T07 Ne d −4.86
2021−11−29T12 Me o +247.67
2021−11−30T14 Me a 1.451
2021−12−01T09 Ne Pg +350.41
2021−12−03T14 Lu xd +241.72
2021−12−04T07 Lu c +252.35
2021−12−04T10 Lu p 0.002385
2021−12−04T11 Lu v +255.03
2021−12−06T02 Lu d −26.33
2021−12−06T03 Me V +258.10
2021−12−08T14
** 
B +90.81
2021−12−16T02 Me d −25.44
2021−12−17T00 Lu xa +61.71
2021−12−17T10 Me v +275.84
2021−12−17T14 Lu V +68.94
2021−12−18T02 Lu a 0.002716
2021−12−19T04 Lu o +87.49
2021−12−19T10 Ve Rg +296.49
2021−12−19T16 Ma xa +244.42
2021−12−20T04 Lu +d +26.30
2021−12−20T07 Ve xd +296.47
2021−12−22T09
** 
S +124.74
2021−12−31T01 Lu xd +241.23



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