This period is known as the eclipse season where three eclipses within the 30 days would take place. There was a penumbral lunar eclipse on June 5th then an annular solar eclipse on June 21st , and another penumbral lunar eclipse on July 4th – 5th . Though ancient myths around eclipses exhibit widespread apprehension, today, thanks to science, we know that eclipses are mere displays of light and shadows. A solar and lunar eclipses occur when the sun, earth and moon are arranged nearly in a straight line. Often 14 days before or after a lunar eclipse, a solar eclipse can occur on a new moon day.
Though this is an annular solar eclipse similar to the eclipse what we have witnessed in Jaffna on December 26, 2019, in this time we will see only the partial solar eclipse part from Sri Lanka. Sri Lakans will not have the opportunity to observe a solar eclipse in another two years as the next solar eclipse due is on October 22, 2022.
On June 21, 2020 from about 10.30 a.m. to 1.30 p.m. people in the the whole country will have the rare opportunity of witnessing this partial solar eclipse for a duration of about two hours and fifty minutes with about 30% of the solar disk is covered by the moon at the time of maximum eclipse.
For those who live in Colombo, the beginning of the partial eclipse can be observed at 10:29 am and the maximum eclipse occurs at 11:51 am and eclipse ends at 1.19 p.m. These timing will change by a few minutes depending on the place of observation. For example, from Matara city, partial eclipse can be observed from 10.34 am, maximum eclipse at 11:53 am and the end of the eclipse at 1.17 p.m.
For the city of Jaffna, partial eclipse begins at 10.24 a.m., greatest eclipse will occur at 11.54 a.m. and the end of the eclipse will occur at 1.30 p.m. Professor Chandana Jayaratne, Director of the Colombo University Astronomy and Space Science Unit, says that direct eye contact with the sun without proper eye protection can cause blindness or other permanent eye damage.
How does a solar eclipse occur?
A solar eclipse occurs when the moon passes in a direct line between the Earth and the Sun. The moon’s shadow travels over the Earth’s surface and blocks out the Sun’s light as seen from Earth.
Because the Moon orbits the Earth at an angle, approximately 5 degrees relative to the Earth-Sun plane(ecliptic), the moon crosses the Earth’s orbital plane only twice a year. These times are called eclipse seasons, because they are the times when eclipses can occur. For an eclipse to take place, the Moon must be in the correct phase during an eclipse season; for a solar eclipse, it must be a new Moon. This condition makes solar eclipses relatively rare.
An annular solar eclipse occurs when the Moon is furthest from the Earth in its elliptical orbit around the Earth. On these occasions, the moon will appear to be smaller and not fully eclipse the sun.
The path of the Moon’s shadow on the Earth
The path of the few hundred kilometers wide patch of umbra (Moon’s dark shadow) is moving at the speed of a jet due to the rotation of the Earth. The annular phase of the solar eclipse is visible only to the people under that strip. Annular Solar Eclipse will start its annularity on 21 June from the Central African Republic in the morning hours and then proceeds to Congo, Ethiopia, Yemen, Saudi Arabia, Oman, Pakistan, India, China and Taiwan. In the South Pacific Ocean, it will end in the evening.
The surrounding areas, including Sri Lanka, where the penumbra (Moon’s less dark shadow) falls will have the visibility of a partial solar eclipse.
How to watch an eclipse safely?
Looking directly into the sun, with or without an eclipse, can cause blindness and other permanent eye damage if you don’t wear proper eye protection, even during an eclipse. You need special protective spectacles or eclipse glasses to watch the sun safely or watch an eclipse. Normal sunglasses (even those that absorb ultraviolet radiation) will not adequately protect your eyes. If you intend to take pictures of the eclipse with a photographic device, there are special solar filters that you can add to make sure that the rest of the sunlight doesn’t damage your vision.
The safest way to indirectly track an eclipse is by using a pinhole camera that you can easily make at home. Take two pieces of cardboard to construct a pinhole camera. Drill a small hole in the center of each piece with a pin or pencil tip. Stay in the sun on your back. On the one hand, hold the piece with the hole in the sun; Place the other side (screen) behind or under. The sunlight will go through the hole and form an image on the screen. If necessary, a mirror can project this light spot into a darker wall.
If you prefer to look directly at the sun, use welders glass with gauge 14 or higher dark filters (which can be purchased from a hardware shop for about Rs. 60.00 rupees) or solar filters. Even with filters never look at the Sun more than 3 minutes continuously. Astronomy and Space Science Unit of the University of Colombo has donated 8 eclipse viewing glasses per each for 256 Vidatha centers throughout the country for the last 2019 December 26th Eclipse. However, under COVID 19 pandemic situation, mass gatherings are not recommended, and it is better to stay home and observe. We are planning to web stream the whole eclipse from Faculty of Science of the University of Colombo through https://www.facebook.com/uocastrosoc/ OR http://fos.cmb.ac.lk/ from 10.25 am and 1:30 pm on June 21st. ) if the sky is clear.
Prof. Chandana Jayaratne
Professor in Physics, University of Colombo and Director, Astronomy and Space Science Unit
University of Colombo