In this image, you can see Jupiter, accompanied by a small dot to its left—one of its Galilean moons. The dark spot visible on the planet itself is the shadow cast by this moon.
In a few weeks time rising in the East in the night sky of Tenerife is a bright object but it’s not a star. It’s been viewed by humans for millennia and our ancestors were probably puzzled by its movements as it appeared to wander in its position relative to other stars in the universe.
It’s a planet and after Venus the moon and the sun it’s the fourth brightest object in the night sky. It’s the largest planet in our solar system and named after the supreme god in Roman mythology Jupiter. Until telescopes were invented it was assumed to be a wandering star.
It’s a massive planet and in mass it is roughly two and a half times bigger than the combined mass of all the other seven planets in the solar system. It’s the fifth planet from the sun and around 4.5 astronomical units from Earth. Or around 800 million kilometres from our planet. It has a volume 1323 bigger the Earth and a mass 317 times bigger than our planet,
It’s the first of the gas planets from the sun and it spins so fast that a Jupiter day is a mere 9.92 hours. Its distance from the Sun means it takes 11.86 Earth years to complete one full orbit around it.
It has a ring system but unlike Saturns is not visible from Earth. It also has over 80 moons and this increases as more and more powerful telescopes are launched into space.
Its four biggest moons were discovered by Galileo in 1410 and he named them after Zeus’s lovers in Greek mythology and in order of size of their radius they are Ganymede 2631Km Calisto 2410Km Io 1822Km and Europa 1561Km. After these four the next biggest moon is Himalia which only has a radius of 85Km clearly too small for Galileo to spot with his home-made telescope. In the clear skies above Tenerife the four Galilean moons are a spectacular sight through one of our large electronic telescopes. The planets stripes are also visible as two brownish bands of colour each side of its equator.
Jupiter is a gas giant which means it doesn’t have a solid surface to land on and if there was a spaceship powerful enough to withstand Jupiter’s immense gravitational pull and its magnetic belt that is 20,000 times stronger then Earths it would encounter first layers of gases and as it headed further towards the core of the planet liquids and finally towards the centre a solid rocky core around 20 times the mass of Earth, The temperatures range from minus 148 degrees Celsius at the surface of its gas layers to around 24000 degrees Celsius at its core which is hotter than the sun.
What we see is the outer surface and this consists of mainly Hydrogen and Helium gases and the colour bands are a result of complex cloud structure in the top 50 Kilometres depth of the planets surface mixing with gases rising from further down and changing colour due to exposure to the Suns ultraviolet rays the areas between the bands are clouds of crystallised ammonia carried up from deeper down and masking the coloured gases. A striking feature of Jupiter is its red spot in its southern hemisphere so large that it could easily accommodate Earth.
To summarise Jupiter is a beautiful sight and in my opinion second only to the lord of the rings Saturn as a wow object to view through one of our large telescopes in the dark night skies we have in Tenerife. Come along soon in the coming months as we approach winter there are many interesting deep sky objects like the Andromeda galaxy the Pleiades open star cluster and the gaseous nebula in Orion, The Milky Way is still just visible but the stars (excuse the pun) of the night in my opinion is the King of the Gods and its four Galilean moons and the Lord of the Rings Saturn.
We hope to see you soon! Booking direct through the site offers a choice of three different types of excursions and the best value for money. We have a limited supply of warm coats to borrow but its always best to wrap up warm with long trousers and stout shoes.
Written by Stephen Phelps
