With the lunar horizon in the foreground, the Earth will pass in front of the Sun on Wednesday, May … [+] 26, 2021, revealing the red ring of sunrises and sunsets along the limb of the Earth.
NASA’s Scientific Visualization Studio
Wednesdays total lunar eclipsethe so-called Blood Moonwill see the lunar surface turn a reddish-copper color for 14 minutes and 30 seconds.
Since Earth will be aligned with the Sun and the Moon, our atmosphere will filter the Suns light onto the Moon as it enters the Earths shadow, essentially projecting thousands of sunrises and sunsets onto the lunar surface.
Thats the glowing red full Moon those west of the Mississippi will see in the early hours of Wednesday, May 26, 2021, but what would the event look like from the Moons surface itself?
It would be nothing less than a total eclipse of the Sun by the Earth!
With Earth hiding the Sun, astronauts on the surface would see a red ringthe sum of all Earths sunrises and sunsetsaround the limb of the Earth.
You would look up and see the Earth, potentially also the city lights on Earth, and you would notice the ground around you turn red, said Dr. Noah Petro, Project Scientist for NASAs Lunar Reconnaissance Orbiter mission thats currently orbiting the Moon.
MORE FROM FORBESBlood Moon Eclipse 2021: Exactly When, Where And How You Can See Next Week’s ‘Super Flower Blood Moon’ Total Lunar EclipseBy Jamie CarterIt would also get really cold.
The lunar surface then cools down substantially during an eclipse as the Moon goes from intense midday Sun to being in darkness, said Petro. Hopefully you wouldnt feel the cooling through your spacesuit. However, the ground around would cool substantially.
It would be a pretty immersive affect the same way as on on Earth during a total solar eclipse when shadows look different and the atmosphere around you cools, said Petro.
A lunar eclipse can be a risky time to have a space mission on the Moon.
NASA is planning to send astronauts to the Moon in late 2024, though that could and probably will slipand there are two total lunar eclipses in 2025 and one in 2026.
MORE FROM FORBES7 Things You Need To Know About Next Week’s ‘Super Flower Blood Moon Eclipse,’ The First Total Lunar Eclipse For Two YearsBy Jamie CarterIt depends on what that mission and its experiments are designed to survive, but it puts your equipment into a totally different thermal regime, said Petro. During the Apollo missions the astronauts were not going to be on the Moon during an eclipse, but the experiments they left behind were.
Day-night cycles are, of course, normal on the Moon. The one big difference of course, is that it’s gets really hot and then it gets cold really quickly, so that thermal change is pretty dramaticand dramatic temperature shifts can do strange things, said Petro, mentioning windshields that crack in temperature extremes.
Plenty of science can be done during a total lunar eclipse and NASAs Lunar Reconnaissance Orbiter (LRO) will, on Wednesday, measure the temperature change on the lunar surface.
Will it survive the sudden onset of cold?
With no sunlight to shine on the solar panels that power its heaters, a spacecraft in orbit can freeze during a total lunar eclipse unless its been specifically designed to cope with that challenge.
MORE FROM FORBESExactly When You Can See This Week’s ‘Super Flower Blood Moon’ Eclipse From Every U.S. StateBy Jamie CarterThe LRO is designed to withstand an eclipse.We’ve been at the Moon now for 12 years so weve gone through a number of eclipses and we know how the spacecraft will respond, said Petro. But early on in the mission, we didnt, so we were very cautious.
NASAs Lunar Atmosphere and Dust Environment Explorer (LADEE)a robotic probe that orbited the Moon in 2013/2014was purposefully designed not to withstand a total lunar eclipse, but it just managed to survive, regardless.
Because its a very short eclipse we know that the battery will not completely deplete during the eclipse and so we can leave the one experiment on to measure the temperature change, said Petro about LRO this week. If it were a longer eclipse we might not do it,
So for missions to the Moon lunar eclipses have become engineering mileposts that have to be planned for in advance.
MORE FROM FORBESBlood Moon 2021: Why Next Week’s Major Sky Event In America Is Defined By The MississippiBy Jamie CarterA total lunar eclipse occurs when a full Moon passes through Earths 870,000 miles/1.4 million km long shadow in space. That happens just occasionally, and it can take anywhere from 105 minutes (like in 2018) to just five minutes (like in 2015).
On May 26, 2021 it will last for such a short time because instead of traveling through the center of Earths shadow it will pass through its northern part, just 21 miles (34 km) from its outer edge. So the Moons northern limb is predicted to be rather bright during totality.
Either way, its an event not to be missed if you happen to be on the night-side of Earth at the right time.
Wishing you clear skies and wide eyes.