The sunsets this weekend, and the following days, offer us a good opportunity to observe the elusive Mercury. Besides, Mars presents us with its beautiful orange glow during the first part of the night. In the middle of the month, we have dismissed Jupiter and Saturn, as they got closer and closer to the glares of sunset, and they are already too close to the line of sight to the Sun to be visible with the naked eye. Also, each day that passes we have more difficulties seeing Venus that is progressively lower in the sunrises. To continue enjoying the course of the planets in the sky, we still have Mars and Mercury. Well, although they are the smallest planets in the solar system, they are now in very good visual condition for observation.


Mars is visible during the first part of the night. We can look for it after sunset high above the southeast horizon. The waxing Moon passed near the red planet on January 20 and 21. On Sunday the 24th, both stars will be well separated, with the gibbous Moon in Taurus and Mars passing north of Cetus (the Whale). The scene in that area of ​​the sky will attract our gaze both by the Moon and Mars and by the extremely bright stars in this region of the sky: the reddish Aldebaran in Taurus, Capella – a little higher – in Auriga and, going down towards the horizon, the magnificent constellation Orion headed by Betelgeuse.

Those with good binoculars or a small telescope will also be able to admire the discreet glow of distant Uranus near the orange disk of Mars. Uranus is a very large planet, its diameter (50,700 kilometers) is 7.5 times greater than that of Mars. However, from Earth, Uranus is now 14.6 times farther than Mars (Mars at 205 million kilometers and Uranus at 3.014 million kilometers). This is why Mars appears very bright, while Uranus, 120 times dimmer, can barely be seen with the naked eye.


It is often repeated that Copernicus lamented on his deathbed that he had never been able to see the planet, Mercury. Although it is only a legend, fed by a poor translation of one of its texts, this gives us an idea of ​​the difficulties to observe the small rocky planet, in particular from the banks of the Vistula, where the Polish genius was born and lived. for much of his life.Fortunately, these days we have from Spain a magnificent opportunity to observe the elusive planet.

Mercury’s yellowish light will shine in the southwest just after sunset. To locate it, it is important to look for an observation point with the western horizon well clear of obstacles and, of course, clouds. And it is advisable not to let the time pass from sunset and look towards that part of the horizon after 6:40 p.m. (peninsular time). The elusive planet will remain visible for just an hour, as it will hide in the west, closely following the path of the Sun, at approximately 7:30 p.m.


These favorable conditions are since Mercury is now at the maximum possible angular separation (slightly more than 18 degrees) from the line of gaze to the Sun. Astronomers say that it is at its ‘eastern elongation’.Let us remember that Mercury is an ‘interior’ planet, that is, it has its orbit contained within that of the Earth. Located on our planet, we can imagine Mercury passing in front of the Sun until reaching an extreme position, to our right, and then we will see it again approach the Sun to pass behind, and appear on the left until it reaches another extreme position on that left side, and so on.

Those extreme positions are the maximum elongations. If the atmosphere allows it, let’s take advantage of these beautiful winter sunsets to observe these two small planets. Besides, the full moon will take place on January 28 in Cancer, offering us another beautiful celestial spectacle, especially in those places where snow has covered the landscape and the reflection of the moonlight helps to illuminate the night so that it can seem supernatural.