• Space. 2020: an excellent year for space exploration

This weekend we can observe three morning stars, Mars, Jupiter and Saturn, and two afternoons, Venus and Mercury. As the month progresses, the Moon will come to join the planets to form beautiful celestial prints.

Three morning stars ...

Let's look up at the sky at dawn on Saturday 15 or Sunday 16, at about 7 o'clock in the morning, about an hour before the sun rises, when the sky begins to clear in the east. The Moon is in the waning quarter phase very high above the horizon, near the meridian.

Below the Moon following the ecliptic line to the east, we can see Mars, Jupiter and Saturn in that order of decreasing elevation. The red planet, which is the highest on the horizon, is now far away, on the other side of the Sun (about 1.8 times farther than the Earth's Sun) and shines discreetly (magnitude 1.3) .

The giant Jupiter appears somewhat lower, but with a brightness 16 times higher than Mars, now dominates the sky before dawn. Jupiter is now 6 times farther than the Sun of the Earth.

Finally, Saturn appears with a brightness similar to Mars but much lower than Mars and Jupiter. If we extend the arm, Saturn's height above the horizon (about 5 degrees) is equivalent to the size of the thumb.

... and two afternoons

Venus and Mercury, are well visible after twilight. A good time to observe them is at about 7:20 p.m., about three quarters of an hour after sunset.

Venus is very bright (magnitude of -4.3) and can be seen until it lies down in the west, after 10 pm (Peninsular time). Venus is now about 150 million kilometers away from Earth, roughly the same distance as the one that separates the Sun from Earth.

Mercury is much lower on the horizon and we are shown about 16 times less bright. Its distance to Earth is only about 120 million kilometers (0.8 times the Earth-Sun distance). Due to its low elevation and its modest brightness, the observation of this small planet is not as easy as that of Venus. It is convenient to look for a place with a clear horizon of obstacles to the west. After locating Venus, we must look down at the earth to locate the discreet glow of Mercury.

Selene visiting

On Tuesday 18, the waning moon arch will come to visit Mars. Both stars will be separated by a distance of about four degrees. On the 19th, the Moon will be close to Jupiter; and on the 20th we will see it very close to Saturn near the horizon.

We can take advantage of these days to observe the delicate cinderella light that makes the night part of the lunar disk shine slightly. It is the reflection of sunlight that comes reflected from Earth: the reflection of a reflection. As the days go by, Selene will be gaining in age, each day she will get up later and less illuminated until she reaches the novilunio that will take place on the 23rd in Aquarius.

Hopefully the skies are clear on these winter days. The Moon will not be an obstacle to observe these five planets: Mars, Jupiter, Saturn, Venus and Mercury. Together with the Earth under our feet, all this reminds us that we live in a wonderful Solar System full of wonders.

Rafael Bachiller is an astronomer and director of the National Astronomical Observatory (IGN)

According to the criteria of The Trust Project

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