The moon is going to disappear for six hours next week in a mega lunar eclipse – the longest for the entire 21st century.
It will be visible across Thailand on July 27-28 between midnight and 6am.
Thai PBS reports that the total phase of the eclipse, called the totality, when the Earth blocks out all light from the sun falling on the moon, will span 100 minutes. The shortest total lunar eclipse this century in 2015 lasted less than five minutes.
Dr Sarun Posayachinda, director of the National Institute of Astronomical Research, said that three astronomical phenomena would take place overnight on Asalha Bucha Day, July 27.
“A partial eclipse precedes and follows the total phase of the eclipse, each time lasting 66 minutes. So, from start to finish, the moon spends nearly four hours crossing under the Earth’s dark shadow. Mars is very bright and red throughout July and August this year, but the eclipse night will be very special.
“The eclipse will happen on the same night that Earth is passing between the sun and Mars, placing Mars at opposition in our sky. In one of the sky’s wonderful coincidences, the Mars opposition happens on July 27 too. It is not just any Mars opposition, but the best Mars opposition since 2003.”
Although the longest eclipse, Sarun said the moon will be smaller than usual because it will be at the farthest point from the Earth this year at 406,000km from the Earth.
He notes that the eclipse night would be the best opportunity to observe Mars when it is a relatively close 57.6 million km from Earth – the closest in 15 years. The average distance is about 225 million kilometres.