Humans have been photographing sunsets from Earth’s perspective for hundreds of years but despite being the only other planetary-mass object people have ever gone to, nobody has photographed a sunset from the Moon.
Here on Earth, we are used to the Sun rising and roughly 12 hours later it sets again. But sunset and sunrise work differently on the Moon; one lunar day lasts roughly 29.5 Earth days (the amount of time it takes the Moon to complete one full rotation on its axis). That means when the Sun rises on the Moon, it doesn’t go away again for another 14 Earth days.
The Apollo missions were timed so that the crew landed on the lunar surface at the start of that two-week window giving them plenty of time to carry out their scientific work. But all of this is to say that no one knows what a sunset on the Moon actually looks like.
The hypothesis is a little grim: With no atmosphere to disperse light, scientists reckon that there will be no gradual transition of colors the way we get here on Earth during golden hour and twilight. Instead, it is believed that day turns to night instantaneously when the Sun disappears below the horizon.
We’re Going to Find Out
Fortunately, we should get to find out this year when Firefly Aerospace sends its spacecraft, Blue Ghost, to Earth’s natural satellite. Blue Ghost is designed to operate at least five hours into the fortnight-long lunar night. With no sunlight, temperatures in the lunar night drop to a dastardly cold 173°C (-280°F).
Blue Ghost has been designed and made at Firefly’s spacecraft facility near Austin, Texas, and has been shipped to NASA’s Jet Propulsion Laboratory in California for final testing. Once ready, it will travel to Cape Canaveral where it will be attached to a SpaceX Falcon 9 rocket and blast off to the Moon for a journey that will take one and a half Moon days (about six weeks).
“After all the hard work, it’s bittersweet to see Blue Ghost leave our Texas-based facility, but we’re more than ready for this final test,” Jana Spruce, Vice President of Spacecraft at Firefly, tells Forbes. “We’ll have a dedicated team of Fireflies with the lander every step of the way as Blue Ghost travels from Texas to California to Florida ahead of this historic journey to the Moon.”
Of course Blue Ghost isn’t going to the Moon for the sole purpose of taking pretty pictures, it will have 10 NASA-supported science instruments on board. Forbes reports that one of its main objectives is to discover how rocks and dust on the Moon react to solar wind during nightfall.
Image credits: Firefly Aerospace