January 2020 – Astronomical Overview

  • The Earth comes on the 5th with 147 million kilometers near the sun.
  • On the 10th, a penumbra eclipse of the moon takes place.
  • Venus is a radiant evening star.
  • Mars shows up in the morning sky.
  • Jupiter appears in the morning sky in late January.
  • Saturn is unobservable in the daytime sky.


  • 01/20/15: Sun enters the Capricorn constellation
  • 01/20/16: Sun enters the zodiac sign Aquarius

Heliocentric view of the planetary system in the first quarter of 2020. The positions of the inner planets for 1rst January (1), 1rst February (2) and 1rst March (3) and 1rst April (4) are illustrated below:

This part shows the outer planetary system including some planetoids at the beginning and end of the first quarter. The arrows indicate the directions to the more distant planets and to the spring point.
Mercury: is right behind the sun far south through the constellations Sagittarius and Capricorn. Already on the 10th he overtakes the daily star. On this day it reaches its upper conjunction with the sun. On the day of the upper conjunction, Mercury is 214 million kilometers (= 1.43 AU) away from Earth. Mercury is in the daytime sky and remains unobservable below the horizon at night. In the course of the January, Mercury gradually grows ever larger Eastern Angular Distance from the Sun, which grows to 14°4 by the end of the month. Under extremely favorable visibility conditions, you can see the nimble planet at dusk deep in the southwest at the end of the month. On the 28th, the bright Mercury sets at 18h07. Around 17h40m you can see him in the increasing darkness. At around 6pm, it is swallowed up in the thick, horizontal layers of haze. By the end of the month, the Mercury sunset at 18h25m was late, the Mercury brightness remained the same.

The encounter with Jupiter on the 2nd, at which Mercury passes 1°30′ south of the giant planet, remains just as unobservable as the conjunction with Saturn on the 12th, which takes place only one degree east of the sun.

Venus appears at the beginning of the year as a brightly shining evening star in the western sky. Our neighboring planet is the first to light up at dawn, long before the other stars are visible. After the sun and moon, Venus is the brightest star in the earthly firmament. The sickle of the waxing moon joins her on the 28th.
In the course of the January, their downfalls are delayed. At the beginning of the year the -4m0 bright Venus sets at 19h23m. On the 31st, on the other hand, it doesn’t set until 20h53m. The venus brightness increases slightly to -4m1.
On the 27th, Venus passes the distant and faint Neptune just five minutes south of the arc. To see Neptune, binoculars or a telescope are required (see Fig. 1.6 on page 39).
Venus still appears relatively small and rounded in the telescope. On the 27th, 75% of the only 15″ large planet disc is illuminated, ten percent less than at the beginning of the year. In the coming months, the apparent Venus diameter will increase and the degree of illumination will decrease. In May, Venus will then appear as a large, narrow sickle, similar to that Earth moon a few days after new moon.

Mars is a planet in the morning sky. On the 7th he leaves the constellation Libra and enters the scorpion, which he leaves on the 15th to switch to the serpent carrier. The red planet moves on the 17th right 5° north past Antares (Alpha Scorpii). Antares means “Mars-like star” because of its reddish color and its proximity to the ecliptic (apparent solar path). Ares is the Greek name for the Roman god of war Mars. Now you can compare the two well. Antares is 1m0 bright, while Mars is 1m4 at the beginning of the month and 1m4 at the end of January.
Mars rises at 5h00m on the 1st, just eleven minutes earlier at the end of January. The apparent Mars diameter on the 31st is a modest 4m8, which is why hardly any details can be seen on Mars in amateur telescopes.

Jupiter has just completed its conjunction with the sun. On December 27th of the previous year, the sun caught up with him in the zodiac. Since the giant planet runs very slowly through the zodiac, its western angular distance from the sun increases rapidly. And since Jupiter is a fairly bright planet at -1m9, it already appears in the morning sky at the end of the month. For the first time you can see the giant planet with its free eyes on the 25th.
It wanders right through the shooter (see Fig. 7.12 on page 159). On the 25th, Jupiter rises at 6h53m. About a quarter of an hour later you can see it as a bright, yellowish point of light just above the southeastern horizon. On the last day of the month, the giant planet rises at 6h34m. The encounter with Mercury on the 2nd remains unobservable.

Saturn rises in the daytime sky with the sun and cannot be seen. On the 13th, it is overtaken by the sun in the Sagittarius constellation and is in conjunction with it. It disappears behind the sun or Saturn is covered by the sun.
On the day of the conjunction, Saturn is 1,648 million kilometers. (=11.02 AU) from Earth. It is separated from the sun by 1501 million kilometers (=10.03 AU).
The encounter with Mercury on the 12th remains unobservable.
On the 10th, Saturn is in a heliocentric conjunction with Pluto. Four days later, on the 14th, the ring planet 0m7 passes the dwarf planet Pluto north.

Uranus becomes stationary on the 11th in the constellation Pisces on the border with Aries. This is hardly noticeable because the greenish planet almost does not move these weeks. By the end of the month it has gone almost unnoticed. Uranus postponed its downfall soon after midnight. On the 1st it goes down by 2h44m, on the 5th by 1h49m and on the 31st by 0h7m.
The best time to look for Uranus is the hour around its culmination. It takes place on the 1st at 19h39m and at the end of January on the 31st at 17h42m. In the first half of the month, moonlight interferes with the observation. Its brightness decreases slightly from 5m7 to 5m8.

Neptune right-driven movement in Aquarius, is chased by the sun and approaches its conjunctive position with it. By the end of January, its eastern angular distance from it has shrunk to just under 36°. This means that the most distant planet has to be removed from the watchlist. It withdraws from the evening sky and becomes unobservable. Its conjunction with the sun is expected in the first third of March. Experienced observers will be able to track down Neptune with suitable optics in the first half of January.
On the 27th there is a very close encounter with Venus. This passes just 0°05′ south of Neptune. At 19h the distance is still eight arc minutes.
On the 1st, Neptune culminates at 16h48m and sets at 22h20m. Its meridian passage takes place on the 15th at 15h54m. The only 7m9 bright Neptune goes down on this day by 2127m. At the latest one and a half hours before sunset, Neptune becomes invisible near the horizon. By the end of the month, the Neptune sunsets are getting to 20h27m.

Planetoids & Dwarf Planets

Pluto, the most famous dwarf planet (planetoid no. 134 340), will also be in the Sagittarius constellation in 2020. On July 15, he comes in opposition to the sun. With 14m3 of opposition brightness, it is only accessible to larger instruments. It is listed in the months of April, July and October under the heading “Planetary Run”.
On the 13th Pluto is in conjunction with the sun at 14h. That day, 5227 million kilometers (=34.94 AU) separate it from Earth. Its solar distance is 5080 million kilometers (=33.96 AU)

Ceres (Planetoid No. 1) comes into conjunction with the Sun on the 13th in the Sagittarius constellation. They separate 584 million kilometers (=3.90 AU) from Earth on this day, while their sun distance is 437 million kilometers (=2.92 AU). This dwarf planet reaches its opposition to the sun on August 28.

Vesta (Planetoid No. 4) stood in opposition to the sun on November 12, 2019. On the 1st it becomes stationary in the constellation of Walßsch and then walks quite right through the zodiac. This ends her opposition period, which is also evident from the decrease in brightness from 7m4 to 7m9. Planetoid No. 4 can be found relatively easily in binoculars.
On the 1st Vesta passes the meridian at 20h23m and sets at 3h14m. By the end of January, her culmination will be premature at 18h37m and her sinking at 1h41m.