Astronomical summer time comes to Bulgaria at 12.42am on June 21, and this year brings a partial solar eclipse on the morning of the summer solstice.
Lasting about an hour and 10 minutes, the partial solar eclipse – which happens when the Moon partially covers the disk of the Sun – is set to begin at 8.01am, reach its maximum at 8.35am and end at 9.11am.
Prospects of the visibility of the partial solar eclipse in Bulgaria are, however, mixed.
Weather forecasts for the country’s four largest cities – Sofia, Plovdiv, Varna and Bourgas – are all for partly cloudy weather at that time of the morning.
Either way, it is not safe to look directly at a partial solar eclipse without using proper equipment or technique – as in all cases, it is never safe to look at the sun with the naked eye.
Nasa has posted some suggested ways of seeing a partial solar eclipse.
“No matter which recommended technique you choose, do not stare continuously at the sun. Take breaks and give your eyes a rest. And, remember, don’t use regular sunglasses — they don’t offer your eyes sufficient protection,” Nasa says.
1) Projection: The safest and most inexpensive way to watch a partial solar eclipse is by projection. Place a pinhole or small opening in a card, and hold it between the sun and a screen – giant sheet of white paper works – a few feet away. An image of the sun will be seen on the screen. Projected images of the sun’s crescent during an eclipse may even be seen on the ground in the small openings created by interlacing fingers, or in the dappled sunlight beneath a leafy tree. You can also use binoculars to project a magnified image of the sun on a white card. However, you must never look through the binoculars at the sun.
2) Filters: The sun can be viewed directly only when using filters specifically designed for this purpose. Such filters usually have a thin layer of aluminum, chromium or silver deposited on their surfaces. One of the most widely available filters for safe eclipse viewing is a #14 (or darker) welder’s glass. A welding glass that permits you to see the landscape is not safe. Aluminized mylar manufactured specifically for solar observation can also be used. Mylar can easily be cut with scissors and adapted to any kind of box or viewing device. Only use filters that you know have been approved for solar viewing.
Unsafe filters include colour film, some non-silver black and white film, medical x-ray films with images on them, smoked glass, photographic neutral density filters and polarizing filters. Solar filters designed to thread into eyepieces, which are often sold with inexpensive telescopes are also dangerous.
3) Telescopes with solar filters: There are sun-specific telescopes available for sale — or perhaps through a local astronomy club — that are also safe for viewing a partial eclipse.