Friday January 18th 2002 - edited by Patty Greenall This week in Astro News: ~ New Planet latest ~ ~ Colour of the Universe ~ ~ The Zodiac: Sidereal or Tropical? ~ New Planet latest The discoverers of the largest new planet in the solar system are just weeks away from deciding a name for it. The astronomers at Lowell Observatory in Arizona met last week to discuss plans to name the 800-mile wide object, currently known only as 2001 KX76. Their final choice of name will be made by team member Jim Elliot. Jim was the first to spot KX76 on a photo image of a region near Pluto, nearly four billion miles from Earth. Jim is looking in detail at our shortlist of suggestions from readers and his decision will be revealed early next month. Colour of the Universe Astro-physicists last week announced that the colour of the universe is bluish green or pale turquoise. How is this determined? Remember that light can be split into rainbow colours by using a prism and conversely, if you mix all the colours of the spectrum together you'll get white light. They gathered spectral data from all light emitted from stars and galaxies - the combined data yielded a single distinctive turquoise colour. Colour is determined by the speed and intensity of a star or galaxy. So the colour will change as the universe ages. The Zodiac: Sidereal or Tropical? Last week in Astronews, Bernard Fitzwalter observed that Jupiter can currently be seen near the twin stars of Gemini. But, astrologically speaking, Jupiter is not in Gemini, it's in Cancer. Here, Bernard explains why. (If you missed any of Friday's Astronews articles, click on the Archive Thought for the Day link in the left hand frame.) If you look up at Jupiter one night this month, having read on this page that it's in Cancer, you'll see it next to the twin stars of Gemini. So why isn't it in Cancer? The simple answer is that there are two zodiacs, and they're not the same. In the 'tropical' zodiac Jupiter is in Cancer; but in the 'sidereal' or star-based zodiac, it's in Gemini. The planets all move through a strip of the sky that encircles the globe. We call this strip the ecliptic. Along it are the 12 constellations, each carrying the name of a zodiac sign. These constellations are of different sizes and, even in India, where most traditional astrologers still work directly with them, there is much debate about exactly where one sign ends and the next begins. Most western astrologers, though, don't use this zodiac. Instead, very deliberately, they use the tropical zodiac. This zodiac divides the Sun's apparent path through the ecliptic into 12 exactly equal sections. These sections are named after the traditional constellations which is where confusion can sometimes arise. The two systems are very different and western astrologers have good reasons for preferring the more precise tropical zodiac. Some who have experimented with the two systems side by side find that the tropical zodiac gives sharper results in questions of timing.