Blue Skies for Everyone – February 2021

By Julia Marin-Yaseli de la Parra

The heavens appear to be filled with fantastic figures of the imagination. In the ancient times, the sky was split up into small pieces for orientation. The classical map of the sky consisted of 48 constellations, according to Greek culture. Much more earlier than that, the Mesopotamia nation used the skies for navigation, as a farming-calendar and inside their religious traditions.  Some of the constellations from Mesopotamia were adopted into the Greek list of figures in the sky. We do not know the origin of many others. The truth is these figures were vital in antiquity. Not only for orientation, since google maps was far away to appear, but as a mixture in between mysticism and science. 

For hundreds of years astronomy was inseparably linked to astrology. Back then, there was no physics or philosophy. Scientists were a union of knowledge that wondered the why of things. And very often religion and science went hand in hand. It is therefore not surprising that astrology, which predicts people’s behavior according to their zodiac sign, was considered a scientific discipline. The truth is that the zodiac is no different than any other constellation in the sky. The Sun simply passes through that region of space throughout the year.

Not so long ago, when my grandfather was young, the shepherds knew every single piece of the sky. Today we do not see the skies so often. It is not our fault. We do not need to orientate with the stars. Light pollution is everywhere, we barely see the less shining stars. BUT that could help us! If we are starting to recognize the constellations, it is easier to do it when we just see the most luminous dots. 

During this month I would like to introduce the Orion constellation to you. That is my favourite constellation, since one great nebula is pretty close to its belt (but we will talk about nebulas in another moment). Orion the Hunter is perhaps the easiest to identify of all constellations, because its three medium-bright belt stars in a short, straight row, which conform Orion’s Belt, the most noticeable part of Orion. These three stars aren’t the brightest in the sky, but they’ll catch your eye. Notice the two brightest stars in Orion, Betelgeuse and Rigel (see picture below). The red supergiant star Betelgeuse, has been making headlines due to a recent drop in brightness. Is an explosion imminent? That would be something really great to observe, so don’t stop looking for it in the Pasadena night sky!

Also, during these days you can observe eye-naked near Orion one Zodiacal constellation, the twins of Gemini. The two bright stars Castor and Pollux form the heads of these twins from Roman and Greek mythology. Gemini is located high overhead in the south. On February 23rd the Moon will be just below Pollux at nightfall. 

On the opposite of the constellations, we have asterisms. This is a pattern of stars that is not a constellation. It can be part of a constellation, and can even span across it. Asterisms are easy to distinguish in the sky due to their big sizes and you can find some of them every season. The most famous asterism from this season is the Winter Circle.

The Winter Circle, or Winter Hexagon is a ring of six bright stars that spans a very wide region of the sky. We already talked about two constellations that form this circle, Orion and Gemini. 

The Winter Circle contains other special groupings of stars too: another wintertime asterism, the Winter Triangle, made of the bright stars Sirius, Betelgeuse, and Procyon. 

You will see them rising in the east early in the evening, during the time of long Californian nights. Watch on February 20th through the 22nd, as the Moon moves along the Winter Circle, growing a bit fuller each evening. 

This picture shows the Winter Hexagon with Orion constellation and the Moon transit across it. Castor and Pollux from the Gemini constellation can be seen at the left of the Moon.

Finally it is very exciting to know that NASA prepares to land its latest rover in the Red Planet, called Perseverance, on February 18th. You will find Mars high in the west after sunset all month long. It should be visible all evening, setting around, or soon after, midnight local time. On the night of NASA’s planned Mars landing, you will find the half-full Moon right next to the Red Planet. So go out and have a look with your own eyes! I will work in  the monitorization of the Martian atmosphere during the landing, with the European mission Mars Express, so do not hesitate to ask me any questions that you have!

NASA mission Perseverance simulation of the landing.
It will hopefully take place this Thursday 18th February around 11:30 PST.

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