We won’t see much of it, but it is special: tomorrow morning Europa, one of Jupiter’s most interesting moons, will maneuver itself right between the Earth and a distant star.

The star’s light will die out for at least a minute from our point of view. A complete star eclipse, caused by a distant moon. In southwestern Africa, the eclipse can be easily seen with a simple telescope.

By observing the event from different locations and comparing the data, astronomers can learn more about Europa’s orbit around Jupiter. That is something many scientists are waiting for, as the JUICE mission is imminent (JUpiter ICy moons Explorer). This mission, which the European Space Agency (ESA) is busy working on, will arrive at Jupiter and its moons in 2031 and conduct all kinds of research in the area.

Goldmine of data
The light from the star shines through the gas clouds of Europa just before and after the eclipse and bends in a certain way. Hopefully, these observations will provide more clarity about the structure of those gas layers.

Thanks to Gaia, this eclipse has come to light. ESA’s mission has provided a wealth of data for years. Gaia aims to map as many stars in our Milky Way galaxy as possible. The exact positions of more than a billion stars on the horizon are stored. Two data packets (DR1 and DR2) have appeared since the start of the operation in 2013.

Space probe Gaia. Photo: ESA

A third package (DR3) packed with new information was released in June. It contains data on almost two billion space objects. Information from the Gaia mission will allow scientists to make predictions about eclipses like Europe’s this month.

For example, Gaia predicted another eclipse on March 31 of this year under the influence of Europe. Previously, only Jupiter’s moons Io and Ganymede were analyzed in this way. So Gaia changed this and made it possible to gather new information through telescopes on Earth during eclipses.

After this, scientists got a taste of it and used the Gaia data to predict even more stellar eclipses. This time for all four of Jupiter’s largest moons, the Galilean moons Io, Europa, Ganymede and Callisto. They were discovered by Galileo Galilei as early as 1610, hence the name.

Invisible Blockage
The June 19 eclipse is so special because Europa is moving in the shadow of its planet Jupiter at the time. So it is impossible to see the moon from Earth, because a moon can only reflect light from the sun. Since Jupiter blocks sunlight during the eclipse, we can only infer the moon’s presence by temporarily blocking the star’s light.

The stellar eclipse takes place in the early morning at 5:05 am and is only visible in southwestern Africa in South Africa, Namibia and Botswana, among others. To the east it is already getting light because of the rising sun.

JUICE mission

The Jupiter Icy Moons Explorer (JUICE) is a special space probe currently being developed by the ESA in collaboration with Airbus. The mission will study three of Jupiter’s Galilean moons: Ganymede, Callisto and Europa, but focuses on the former. All three moons are believed to have liquid water beneath the surface, making them potentially habitable. JUICE will launch in April 2023 and should arrive at Jupiter more than eight years later in July 2031. In December 2034, the robotic probe will orbit Ganymede for a close-up mission of the moon. This makes JUICE the first spacecraft to orbit a moon other than our own moon. JUICE wants to try to find underground water reservoirs, map the surfaces of the moons, study what the moons are made of right down to their core and examine the extremely thin atmosphere.

Navigating Ice Worlds
Events like these allow the location and movements of Europa and other moons of Jupiter to be calculated even more precisely. This is important for the upcoming JUICE mission. It will soon be possible to navigate accurately between the ice worlds and to collect a mountain of new data along the way. For example, the mission can make more accurate calculations of the material that makes up the moons.

The prediction of this eclipse based on the Gaia data shows once again how useful star information can be. It accelerates the search for information about asteroids and moons in our solar system.