As the Moon orbits Earth, its gravitational pull creates tides in our oceans. And Earth returns the favor — its gravity creates tides in the lunar crust.

The big moons of the planet Jupiter also experience the effects of tides. Each one feels a tug of war between Jupiter and the other moons. That creates tides that can have dramatic effects. Io, for example, is covered by hundreds of volcanoes — fed by rock that’s melted by powerful tides inside the moon.

The moon Europa experiences tidal effects as well. Its interior is pulled and squeezed, generating heat that melts some of the ice below its crust — producing a global ocean. It probably contains more water than all of Earth’s oceans combined.

There’s evidence that some of the water in that ocean squirts high above Europa — perhaps through cracks in the crust created by the tides.

Hubble Space Telescope has detected possible plumes of water shooting out from near the south pole. They rise up to 125 miles above the surface. Most of the water probably falls back onto Europa, creating fresh ice.

The discovery means that a future spacecraft may be able to sample Europa’s ocean without drilling through its ice — simply by flying through plumes of water created by the tides.

Look for Jupiter to the upper right of our own moon at first light tomorrow. It looks like a brilliant star. The true star Spica, which is fainter than Jupiter, is to the lower right of the Moon.

Script by Damond Benningfield