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Historical Events  Science
Jupiter

Found less?

MMDE: Over 300

Current: Under 100

Recent reports that Jupiter now has 79 moons are causing many people to point to this as a Mandela Effect, because they remember NASA announcing there were "over 300" years ago.

The first moons were discovered by Galileo in 1610, hence them being named the "Galilean moons". In fact, people with exceptional eyesight can actually see them unaided due to their size. Ganymede, for example, is larger than Mercury.

Whilst there has always been controversy regarding classifying objects in the solar system - see the great "is Pluto a planet" debate - it seems a far fetch to miscount several hundred moons from the same planet this way.

Dwarf planet sized moons

If the Galelean moons were orbiting the sun, they would be classed as dwarf planets. 

The search for planet nine

In July 2018 astronomers were searching for the fabled "planet nine" when they discovered 12 new moons round Jupiter. They then announced the total number of moons was 79.

Oddball moon

One of the moons was described as an "oddball" because it had the opposite rotational orbit to the rest. This means it could collide with one the same was a car going the wrong way down the freeway could. It's probably happened before, and many times, but the chaos that caused will have all settled down to what we see today. Such a collision could also throw out the orbits of the other stable moons.

Carnegie’s Scott S. Sheppard, who lead the team making the new discovery, said:

Jupiter just happened to be in the sky near the search fields where we were looking for extremely distant Solar System objects, so we were serendipitously able to look for new moons around Jupiter while at the same time looking for planets at the fringes of our Solar System. 

Jupiter has "over 300" moons?

It might be that one day the "over 300" figure proves to be true, but for those who remember the announcement it will just be one big catch up.