Stargazers will be treated to a once in a lifetime lunar eclipse this week, when the Moon could turn a deep shade of burgundy, or vanish completely, as it falls into the Earth’s shadow.
The eclipse will be the longest of the 21st century, lasting from 8.49pm to 10.13pm in London on Friday evening, and the Moon will stay close to the horizon, giving the illusion that it is far larger than usual.
The phenomenon will be all the more spectacular because raging forest fires across the globe could alter the Earth’s atmosphere enough to make the satellite appear a deeper red than the usual orangey ‘blood moons’ which are common during a lunar eclipse.
At the same time, Mars is nearing its closest point to the Earth since 2003, and so will appear large, red and bright nearby.
The Moon can turn yellow, orange, red of even black during an eclipse
The Moon can turn yellow, orange, red of even black during an eclipse Credit: Eddie Mulholland
Dr Francisco Deigo, of University College London’s Department of Physics and Astronomy said: “If the atmosphere is contaminated, such as from wildfires then it will affect the light that gets to the Moon and we could end up with it looking deep red or even burgundy.
“If there is ash in the atmosphere from a volcano, such as the recent eruption in Bali, it could even disappear completely. I watched a lunar eclipse as a child when the Moon went black.
“In the future it might be possible to monitor the atmosphere and the impact of climate change by measuring this change in light during an eclipse.”
In a lunar eclipse, the Earth, Sun, and Moon are almost exactly in line with the Moon on the opposite side of the Earth from the Sun, leaving it languishing in our shadow.
Without the strong reflected light from the Sun the Moon dims dramatically, lit only by the sunlight which passes through Earth’s atmosphere. But because the atmosphere has the effect of scattering blue light, the lunar surface appears red.
The lunar eclipse will be visible just above the horizon on Friday evening from Britain
The lunar eclipse will be visible just above the horizon on Friday evening from Britain Credit: Toby Melville
Mark Birkinshaw, professor of cosmology and astrophysics at the University of Bristol said: “If there’s extra dust in the Earth’s atmosphere, then the red colour of the Moon may be stronger than usual.”
Mars and the Moon will both be in front of the stars of the constellation of Capricorn just above the south-eastern horizon.
Morgan Hollis of the Royal Astronomical Society said: “Mars may be the easier of the two to pick out, as it will be significantly brighter than the lunar disc during the eclipse.
“And unlike a solar eclipse, both the eclipsed Moon and Mars are completely safe to look at with the naked eye.”
The eclipse will be the longest one of this century, although there will be another one only a few minutes shorter in 2029. Stargazers will need to wait until June 9 2123 for a longer eclipse.
Andrew Coates of the Department of Space and Climate Physics at UCL said: “The current heatwave will hopefully encourage people to go outside in the slightly cooler evening to view the red moon near the horizon, and with the added bonus of a much smaller, but red and unusually bright, Mars nearby at the same time
“The last time Mars was this close and bright (a ‘perihelic opposition’) was August 28, 2003, but there was no lunar eclipse simultaneously.”