Jupiter: Our Solar System's Cosmic Hoover

As featured on 102.4 Radio Hartlepool's Solid Gold Sunday with Andy Fleming

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Impact spots in the cloudtops of Jupiter made by fragments of Comet Shoemaker-Levy 9 that crashed into the planet in July 1994. Credit: Space Telescope Comet Team & NASA

ANDY FLEMING casts his binoculars at our Solar System's huge gas giant planet, Jupiter and discovers how it protects Earth from Killer Asteroids!  It's the Solar System's cosmic hoover!

What’s that really, really bright star over in the east at the moment that's dominating the evening sky?

Well actually, it’s not a star it’s the solar system gargantuan gas giant planet Jupiter, which is making its presence felt in no uncertain terms at the moment.  Jupiter is nearly large enough to be regarded as a failed star.  It has a similar composition to the Sun that is mainly hydrogen and helium and emits large quantities of radiation.

It’s easy to tell it’s not a star as planets don’t twinkle.  Planets are very close to the Earth in astronomical terms and hence unlike stars aren’t point sources of light, but show proper discs.  If you look at Jupiter with binoculars you'll probably see on either side of it some of its entourage of moons. With a telescope you should be able to make out a couple of dark belts crossing its disc. These are the planet’s spectacular cloud bands composed mainly of methane and ammonia… impurities in the planet’s immense atmosphere.  Look closely and you’ll see a gigantic red spot… a huge storm that has raged for over 400 years!

For the past few years Jupiter has been rather low in the sky, but now  it's getting easier to see, and the later you stay up in the evening, the higher it gets.  Later in the year it will be totally dominating the night sky.  It is the third brightest object in the night sky after the Moon and Venus.

Last month a brief bright flash was seen and videoed on Jupiter. This was probably the impact of an asteroid or comet, similar to the impact of Comet Shoemaker-Levy 9 in 1994 which created giant bruises in Jupiter's atmosphere which lasted for months. But this time, no scars or disturbances were seen. Many astronomers now regard the planet as the solar system’s gigantic hoover, protecting the innermost planets from killer asteroid and comets, and allowing time for life on Earth to evolve.

Sometimes however, these huge rocks from space get through and impact the Earth, such as the one that killed off the dinosaurs!