MNS Selangor - Astronomy Special Report of Pulau Dayang Trip

A Solar Eclipse is a natural phenomenon. This happens when the Moon moves in between the Earth and the Sun thus casting a shadow onto the surface of the Earth. People living within this shadow will experience either a partial eclipse, a total eclipse, or an annular eclipse.

Diagram 1 : Total Solar Eclipse

A Total Solar Eclipse

The Moon's orbit around the Earth is not a perfect circle but an ellipse. therefore its distance from the earth varies from time to time. The same applies for the Earth's orbit around the Sun. Therefore the Sun and the Moon observed from Earth can vary in size at different times. A Total solar eclipse occurs when the Moon is at the distance from the Earth that makes it exactly the same size as the Sun (as seen in the sky). When an eclipse happens, the Sun is covered totally and the sky turns dark. See Diagram 1.You can observe a Total Solar Eclipse without any solar filters. Observing this event without any visual aids is totally safe.

An Annular Eclipse

An Annular Eclipse occurs when the size of the moon as seen from Earth is slightly smaller than the size of the Sun (as seen from Earth). When this happens, the moon eclipses the Sun, but does not completely cover it thus creating a ring. See Diagram 2. Throughout an Annular Eclipse, it is dangerous to look at the Sun without a proper filter.

Diagram 2 : Annular Eclipse

On May 15th, 1836 during an Annular Eclipse in Scotland, Francis Baily made an important discovery. When the Moon eclipsed the Sun, he saw little specks of light from the Moon. This occurred because the Moon's surface is imperfect and light can go through the uneven parts of the Moon's surface.

The phenomenon is referred to as Baily's Beads. The complex movement of the moon makes the Baily's Beads for every eclipse different. By taking pictures of the Baily's Beads, we can contribute to the research of Professional Astronomers. Data collected can assist the research on our Moon.

A safe solar filter to use for observing the sun directly is made of Mylar - a very tough engineering plastic - which is precisely coated with aluminium and reflects 99.999% of the sun's rays, including the invisible but very harmful ultraviolet and infrared components.

Another alternative would be to use a fully exposed SILVER film, the black-and-white photo negative. DO NOT USE black exposed or unexposed films , 2 CDs put together or any other filtering method. Please take care of your eyes. Your retina can be burnt even without you knowing it! Retina burns are slow and painless.

There are two cheap alternatives and very much on the fun side to use. The cheapest is to stand under a tree during the eclipse. The tree's limbs will work as tiny pinholes projectors to cast a multitude of crescent Suns on the ground. If you place a white sheet under the tree, the crescents will be more ovious.

The other way is more into working with your hands, which kids love. Get an used shoe box, a piece of aluminum foil, a piece of white paper or cardboard and a pin. At one end of the box, without the top, open a hole about the size of a coin, two centimeters diameter. Cover it with the foil and with a pin open a tiny hole in the middle of the hole through the foil. On the other end of the box, at the inside place the piece of paper. The part of the box with the hole place it towards the Sun at on the paper you will get the Sun's image. You can build it in advance and use it anyday with the Sun.