All planets visible to the naked eye can be observed in the night sky of December 2020
Mercury will be visible at dawn until the 6th in the constellation of Libra , then moves to the constellation of Scorpio. It is visible to the south-east. Its magnitude at the beginning of the month ranges from – 0.9 to -1.1. See here all the information about the “ Mercury Observation ” and about the “ Visibility of Mercury in 2020 ”.
Venus will be visible at dawn in the constellation of Libra , moving to the constellation of Scorpio and then to Ophiuchus . It is in the Southeast direction. Its magnitude at the beginning of the month ranges from -3.8 to -3.7.
Mars will be visible at night in the constellation of Pisces, its reddish hue will help its identification. On the 23rd, Mars will be 6 ° N from the moon at 7pm. It is in the Southeast direction. Its magnitude over the month ranges from -1.3 to -0.4.
Jupiter will be visible in the first few hours after dark in the constellation of Sagittarius , then moving to the constellation Capricorn . It is in the Southwest direction . Its magnitude over the month is -2.0.
Saturn will be visible in the first hours after dark in the constellation of Sagittarius , then moving to the constellation Capricorn . It is in the Southwest direction. Its magnitude over the month is 0.6.
Birth table, meridian passage and sunset of the planets
Uranus and Neptune also visible in the December night sky
Uranus will be visible in the constellation Pisces and Neptune will be visible in the constellation Aquarius, where it will remain for the rest of the year. The planets Ú peroxidase and Neptune will be observed withtelescope, since they are not visible to the naked eye.
For more information about the “ Visibility of the Planets ” see on our website the page Almanacs / Data of 2020 / Visibility of the Planets in 2020 and also see the table Birth, Meridian Passage and Occasion of the planets (Lisbon).
The meteor shower of Gemínidas and Urrsidas in December.
This month the Earth crosses the orbit of the Asteroid Phaeton and it is the “debris” left by this asteroid that are responsible for the meteor cluster that takes place annually between December 4th and 17th: the Gemínidas cluster. The name of this cluster results from the traces of its shooting stars that seem to come out of a point in the constellation of the Gemini (the radiant).
Observation of the Gemínidas peak occurs on the 14th at 01:00 (00:50) in the morning, with the number of meteors per hour estimated at an assigned average of 150 per hour, due to the fact that it is a new moon (since the New Moon will occur on the 14th at 4:17 pm). Thus, there will be very good observation conditions for the meteor shower of Gemínidas.
The Earth also crosses the orbit of Comet Tuttle and its remains are responsible for the Ursida meteor shower, which takes place annually between 17 and 26 December. Forecasts show that December 22, is the peak of maximum intensity of this rain, which starts around 10 am. The number of shooting stars observed is not very high, only 10 meteors per hour. The name of this cluster results from the traces of its shooting stars that seem to come from a point in the constellation Ursa Minor (the radiant). The Ursida radiant is circumpolar in most locations in the northern hemisphere, as is the case in Portugal.
Those in love with this type of phenomena, and the curious in general, may lose a few hours of sleep in the coming nights to enjoy this beautiful show. To observe them, we advise you to avoid cloudy nights, light pollution from large cities and look for an unimpeded horizon.
Table with information on the meteor showers of Gemínidas and Úrsidas
Note: the moments are referenced to winter time for mainland Portugal.
For more information on “Meteoroid clusters”, as well as a little information about the history of this cluster, see the Meteoride Clusters page on our website.
Moon phases in December
As is well known, the phases of the moon are determined by the relative positions of the sun-moon-earth system. As the moon moves around the Earth, both stars progress around the sun, occurring every Full Moon month when there is a Sun – Earth – Moon alignment. The New Moon occurs when there is an alignment of the Sun – Moon – Earth type and in the intermediate positions there is the Fourth and First Quarter Moon. The period that the moon takes to pass through the same phase is 29.5 days, known as the synodic month (or a lunation).
The lunar orbit in December
The moon’s orbit is approximately a 5.5% average eccentricity ellipse. The moon takes 27.3 days to complete the translation (one lunar month). The elliptical orbit causes the moon to be closer, sometimes farther from Earth. The closest orbital point to Earth is called Perigee and the furthest point is called Apogee. The average Earth-Moon distance is <dTL> = 384,400 km. The table below indicates the moments of the lunar apogee and perigee with the distance from the Earth to the Moon in units of RT (Earth Ray).
Table with information about the Apogee and Lunar Perigee
For more information about the “ Apogee and Perigee lunar ” see on our website the page Almanacs / Data of 2020 / Apogee / Perigee lunar and also see the Apogee / Perigee lunar and distances Earth-Moon .