IO, Surabaya – Indonesians were finally able to witness a lunar eclipse passing through their skies, on Saturday (28/7/2018) midnight. The natural phenomenon was the second lunar eclipse this year, after the appearance of a super blue blood moon (lunar eclipse along with the blue and supermoon events) on January 31st. The difference: the recent lunar eclipse did not coincide with any other natural event.
Saturday (28/7) midnight, all parts of Indonesia could witness a total lunar eclipse with the longest totality phase of a century. This natural phenomenon is a rare appearance occurring every 100 years. In response to this, a theoretical physicist of the Sepuluh Nopember Institute of Technology (ITS) Surabaya, Dr Rer Nat Bintoro Anang Subagyo supplied an explanation.
Bintoro said the lunar eclipse total phase lasted for 103 minutes. It is estimated that the penumbra phase will begin to appear at 00.14. a partial eclipse will become apparent from 01.24, while the total eclipse will be witnessed around 02.30 and is predicted to be complete after the dawn prayer time. “This eclipse will actually end at 06.28, but it cannot be observed since the moon’s position will have moved it beyond the horizon,” said Bintoro.
Based on the cycle, the lunar eclipse with the longest period of absolute phase will again occur on June 9, 2123, with a duration of 106 minutes. This is similar to Super Blue Blood Moon in January, which will be repeated 100 years later. “This is the second time a rare eclipse phenomenon could be observed in Indonesia,” he said.
He explained this long duration is due to the passage of the moon at a point almost near the centre line of the earth’s dark shadow (umbra), hence it will be shadowed for a relatively long time.
The aphelion event, Earth’s farthest distance from the sun, which happened in July, is also suspected to be the cause. “At the peak of the eclipse, earth-sun distance is about 184 thousand km farther compared to the perihelion stage, or to as far as 151.8 million km,” he said.
Like the lunar eclipse in general, he says, the early dawn eclipse can be seen with the naked eye. “No need to use glasses like the solar eclipse,” he said. As such, he hopes, people in Indonesia, especially in Surabaya, will not miss this rare phenomenon.
According to Bintoro, although Surabaya is not included in the list of 20 monitoring points announced by the Meteorology, Climatology and Geophysics Agency (BMKG), the weather in Surabaya is currently quite supportive for self-observation. Supported by the available equipment, Theoretical Physics and Natural Philosophy Laboratory of the ITS Physics Department will also conduct observations on the fourth floor of its F Building.
He believed that his laboratory equipment is quite capable of producing superior documentation. “I hope with the observations that will be done later, ITS can have proper videos or images of this once-in-100 years phenomenon,” Bintoro said. (ITS)