That is because the planet Mars is beginning to put on a rather nice display in the morning sky in the run-up to its opposition in early December.
The fourth planet from the sun is moving through the constellation of Taurus, the Bull. The planet rises in the northeast just before 1.30am. By 4am it is some 20 degrees above the horizon, shining as a bright orange-red star. You should have little difficulty picking out Mars, which forms the lower apex of a celestial triangle with the stars Aldebaran and Betelgeuse. Incidentally, as both Aldebaran and Betelgeuse have low surface temperatures, they appear orange-red. It will be interesting to compare the contrasting colours of the three objects with the naked eye.
However, if you are having problems finding Mars, next Saturday morning the moon can be used as a handy guide. As is shown in this week’s accompanying chart, the 70% illuminated waning gibbous moon will be below and to the left of the red planet. This week Mars is just over 105 million kilometres from Earth. If you do have a telescope and point it at Mars you will notice that the planet’s tiny disc is just 90% illuminated.
By looking at Mars we can remind ourselves of the vast range of cyclical rhythms to be found when observing the heavens. We are all familiar with Earth’s rotation which turns day into night roughly every 24 hours.
On a longer time scale, our planet’s axial tilt and orbital motion around the sun give rise to the annual pattern of the seasons. Did you know that the planet Mars appears in the same part of the sky relative to the sun every 780 days? Astronomers call this the planet’s synodic period. We know that Mars was last opposite the sun in October 2020, and one synodic cycle later, the planet will again be in opposition on December 7 this year.
