In the past few centuries, Eris was really a southern object, whose position around A.D. 1800 was within the southern constellation of Indus. Eris then crossed through Indus and into northern Tucanae until about 1817, before moving into southern Grus, where it stayed until the early 1840s. From then Eris moved into Phoenix around 1874, then onto Sculptor until 1930, and thence into the equatorial constellation of Cetus the Whale. Eris will remain within this same constellation between 2006 and 2015, and does not it until 19th February 2037 !
Into our future, Eris will gradually move into the zodiac constellation of Pisces where it will stay until the 20th May 2060 AD. It will cross back and forth between Cetus and Pisces several times for a decade or so, where it will move into zodiacal constellation of Aries on 10 April 2065. Next, Eris will leave Aries and become a northern object in the non-zodiacal constellation of Perseus sometime in June 2127. After 2175 AD, Eris will become a far northern object, residing in Camelopardalis until the 23rd Century, when the declination reaches its maximum of around +64°N in 2200 AD.
It should be importantly noted that these positions and times remain tentative because the lack of historical data on the observed positions. So far the oldest identified position is from one plate made on 20th January 1963, meaning that we have orbital information based on just 45 years (2008) or just 8% of the entire orbit.
All sky positions given below should be sufficiently accurate for most amateur purposes. However, beyond the next few decades, future ephemerides may change slightly with adjustments in the orbital elements. Perhaps the greatest difficulties are assessing the many perturbations caused by the gravitational pull of the other planets and planetary bodies in the Solar System. Better knowledge of these effects will likely be determined in the coming decades.
Telescopically, distant Eris only appears as a very faint ‘star’ but remains invisible to all amateur telescopes. It is possible to record the faint body by amateur deep CCD images, though its detection likely requires a lengthy exposure of at least 20cm in aperture.
At times of perihelion (closest to the Sun) Eris can even outshine Pluto during its long orbit in through the depths of the Solar System, reaching the maximum visual magnitude of about 15.5. When the dwarf planet is furthest from the Sun (aphelion) this brightness may drop as low as 18.8 visual magnitude.
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Comparison of Eris and Pluto : 1800-2200
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Mag. Mag. r Delta Elong L b
Min 18.8 16.0 97.6 98.5 178.8 360.0 40.9
Max 16.1 13.7 52.0 51.3 000.7 0.0 -44.6
Mean 18.2 15.3 84.7 84.7 089.3 129.8 -11.8
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Eris 2008
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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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-- 2007 --
29 Dec 01 36.3 -05 08 18.8 96.56 96.79 103 Cet
-- 2008 --
12 Jan 01 36.2 -05 06 18.8 96.79 96.79 089 Cet
26 Jan 01 36.2 -05 03 18.8 97.03 96.78 076 Cet
09 Feb 01 36.4 -04 59 18.8 97.24 96.78 062 Cet
23 Feb 01 36.7 -04 55 18.8 97.43 96.78 048 Cet
08 Mar 01 37.1 -04 51 18.8 97.59 96.78 035 Cet
22 Mar 01 37.6 -04 46 18.8 97.69 96.78 024 Cet
05 Apr 01 38.1 -04 42 18.8 97.74 96.77 015 Cet
19 Apr 01 38.6 -04 39 18.8 97.74 96.77 016 Cet
03 May 01 39.2 -04 35 18.8 97.68 96.77 025 Cet
17 May 01 39.7 -04 33 18.8 97.57 96.77 037 Cet
31 May 01 40.1 -04 31 18.8 97.42 96.77 050 Cet
14 Jun 01 40.5 -04 30 18.8 97.23 96.76 063 Cet
28 Jun 01 40.7 -04 30 18.8 97.01 96.76 075 Cet
12 Jul 01 40.9 -04 31 18.8 96.79 96.76 088 Cet
26 Jul 01 40.9 -04 33 18.8 96.56 96.76 101 Cet
09 Aug 01 40.8 -04 35 18.8 96.34 96.76 114 Cet
23 Aug 01 40.6 -04 38 18.8 96.14 96.75 127 Cet
06 Sep 01 40.2 -04 41 18.8 95.98 96.75 140 Cet
20 Sep 01 39.8 -04 44 18.7 95.86 96.75 152 Cet
04 Oct 01 39.3 -04 47 18.7 95.79 96.75 163 Cet
18 Oct 01 38.8 -04 50 18.7 95.78 96.75 165 Cet
01 Nov 01 38.3 -04 52 18.7 95.83 96.74 157 Cet
15 Nov 01 37.8 -04 53 18.7 95.93 96.74 145 Cet
29 Nov 01 37.4 -04 54 18.8 96.08 96.74 132 Cet
13 Dec 01 37.1 -04 54 18.8 96.27 96.74 118 Cet
27 Dec 01 36.8 -04 52 18.8 96.48 96.74 105 Cet
-- 2009 --
10 Jan 01 36.7 -04 50 18.8 96.72 96.73 091 Cet
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Date : Universal time, which is essentially
Greenwich Mean Time
RA / Dec. : Right Ascension and Declination
V. Mag : Photo-visual magnitude of Eris
Δ A.U. : Distance from Earth in Astronomical
Units
‘r’ A.U. : Distance from Sun in
Astronomical Units
El. : Elongation from the Sun in degrees
(Opposition = oppose the Sun near 180 degrees.
Conjunction 0 deg.)
Con. : Constellation
************************ Opposition Conjunction ************************ 14 Oct 2008 10 Apr 2008 to 14 Oct 2012 10 Apr 2012 and 15 Oct 2013 11 Apr 2013 to 15 Oct 2017 11 Apr 2017 and 15 Oct 2018 11 Apr 2018 to 15 Oct 2022 11 Apr 2022 *************************
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.
