The March night sky.jpg

The March night sky

Clive Jackson is the Director of the Astronomical Observatory of Tavira (Sitio do Malhão, Tavira) and the Camera Obscura (next to the Castle in Tavira), specialising in education and public outreach.

WELCOME TO the March night sky. This month, winter officially ends at the spring equinox and it will happen on March 20. What exactly determines the date is the position of the Sun during its year-long trip around the ecliptic.

In reality, the Sun is not moving. It is actually our planet Earth that is travelling around the Sun but from our point of view it is convenient to imagine that we are still and everything else is on the move.

At the moment, the rotational axis of our planet is tipped at 23.5 degrees to the plane of our orbit and it is this that gives us our seasons.

But twice during a one-year period, exactly between the summer and winter Solstice, our axis is in line with our orbit and this means that from all over the world the Sun appears to rise exactly in the East and set exactly in the West, and the day and night are of the same length.This is the definition of the word Equinox.

This month, the planet Saturn is still visible in the constellation of Leo and on March 19, the nearly Full Moon will be just below Saturn.

On March 14, the First Quarter Moon will be close to the planet Mars that is still in the constellation of Taurus.

Many of us know that the brightest star in the nighttime sky is Sirius, located in the constellation of Canis Major.

But not many know that the second brightest star is called Canopus and it is just visible from the Algarve.

This star is 53 degrees south of the celestial equator and is a white super giant star.

To see Canopus, you will need a sea southern horizon and a pair of binoculars.

Soon after sunset in March, when the constellation of Orion is due south in the sky, you may just glimpse a flashing pinkish coloured star right on the southern horizon.

The colour of the star is normally white but it is so low in the sky that it will change to the red end of the spectrum due to the absorbing of the blue light in our atmosphere.

Canopus will only be visible for 20 minutes or less in the night sky per night as it moves across the southern meridian of the heavens.

Looking towards the west, the seven heavenly sisters, called the Pleiades, are heading down towards the horizon.

These stars are all young and bluish white in colour and are just over 400 light years away from Earth in the constellation of Taurus.

The Pleiades are not a constellation but a galactic star cluster formed in our Milky Way Galaxy relatively recently.

Right overhead during March evenings, we have the constellation of Gemini well visible.

The two stars that make up the heavenly twins are called Castor and Pollux.

These stars are supposed to be identical twins in Greek mythology but in reality they are not quite the same.

Castor is a brilliant white colour and it is in fact a multiple star through a powerful telescope, whereas Pollux is noticeably orange in colour and slightly brighter than its brother.

The Moon is New on March 7, at First Quarter on March 14, Full on March 21 and at Last Quarter on March 29.

For more information, please call Clive Jackson on 281 321 754, fax 281 324 688, email cdepa@mail.telepac.pt or visit http://www.cdepa.pt