What’s that really, really bright star slightly south west of overhead (or zenith) at the moment that you can see from all over the Northern Hemisphere at dusk? 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 four hundred years!
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 four hundred years!
