Three astronomical phenomena this month

Three astronomical phenomena will be taking place this month: two eclipses and a transit of the planet Mercury.

The public relations officer of the Astronomical Society of Malta, Saviour Grech, said there will be a total lunar eclipse, a partial solar eclipse and the planet Mercury will transit the sun's disk.

These phenomena show, in real time, the motion of the moon as it orbits the earth and Mercury circling our nearest star, the sun.

The first phenomenon will occur on Wednesday when Mercury passes across the solar disk as seen from earth. First contact occurs at 7.12 a.m. and the planet leaves the solar disk at 12.32 p.m.

This event will be visible through a telescope equipped with a special filter or by projecting the sun's image on a screen.

Such events are scientifically useful for calculating the sun's diameter, which is thought to vary over a period of 11 years by as much as 290 kilometres.

On the morning of May 16 the moon plunges into the shadow of our planet. It enters the earth shadow, known as the umbra, at 4.03 a.m. and a growing notch of darkness will be seen on its surface. The total eclipse starts at 5.14 a.m. in creeping twilight. The only light reaching the moon's surface would be light that is "bent" on passing through the earth's atmosphere and the moon's colour will change to copper red.

On May 31 it will be the sun's turn to be eclipsed when the moon will pass between the earth and the sun. Only a fraction of the eclipse will be seen from the Maltese islands. Sunrise on May 31 will show the sun partially eclipsed.

The sun must be viewed through a filter such as dark welding glasses to avoid permanent eye damage.

The Astronomical Society of Malta will host a lecture by Frank J. Ventura on the three phenomena. The lecture will be held at Villa Bighi, in Kalkara on Monday at 6.30 p.m.