Astronomy Archives

Astronomy

Vulcan – The (hypothetical) planet between Mercury and the Sun

How many planets are there in the solar system? If you went to school sometime before 2006 you’re likely to say 9. Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. However, since then, Pluto has been demoted to “dwarf planet” due to the discovery of several other objects of the same size and composition beyond Neptune. One such object, Eris, is actually bigger than Pluto. If Pluto is a planet so are hundreds of other celestial bodies. Hence the reclassification. Pluto was discovered in 1930, but 100 years or so before, there was another candidate to the planetary club. …

You can’t see the Great Wall of China from space

It’s an often quoted myth but it is not true at all that the Great Wall of China can be seen from space. From up high, above the atmosphere, it’s possible to see city lights and also, according to this Popular Mechanics article, the vast greenhouses of Almeria, in Spain. The Great Wall of China is really rather long (over 6000km) but it is also very narrow, on average about 6 metres wide (ranges from 5m to 9m) and doesn’t stand out much from its surroundings. To be able to see it from near-earth orbit (160km up) you’d need to …

6 surprising facts about the moon

There is no dark side of the moon, really. As a matter of fact, it’s all dark. The only thing that makes it look light is the sun. Gerry Driscoll, Pink Floyd, “Eclipse”, The Dark Side of the Moon. The moon is the only natural satellite of the planet we call home. It is much smaller (27% the diameter of the earth) and less dense (60% of the density of the earth) which makes it just 1.2% of the earth’s mass. It is also the second brightest object in the sky, after the sun. Here are six interesting facts about …

If there are infinite stars, why is the sky dark at night?

Go outside tonight and look up into the sky. What do you see? A bunch of bright points in the sky: the light from far away stars (unless you’re in Britain, in that case the sky will probably be cloudy). But most of the sky is dark. Even if you go somewhere with very little light pollution (like the middle of the Sahara desert, for example) the sky will be dark. Sure, you’d be able to see more stars more clearly and observe the milky way in all its glory but the sky will definitely not be as bright as …

How much water would you need to put out the sun?

The sun is a giant ball of gas that burns at the centre of the solar system. And the adjective giant is not unearned: the sun constitutes 99.86% of the mass of the solar system. Without it life as we know it would not exist. Water would not be liquid. Plants would not be able to photosynthesise. Without the sun the earth would just be a big icy rock floating through interstellar space. But let’s assume you have a death wish and want to try to put it out. How much water would you need?

The USSR landed probes on Venus over 30 years ago, is it time to go back?

The atmosphere of Venus is over ninety-five per cent carbon dioxide, the pressure at the surface is 92 times that of earth and the average surface temperature is 735 K (462 °C; 863 °F), higher than the melting point of lead. Not to mention that there are large clouds of sulphuric acid raining down corrosive droplets and winds on the surface that can reach 300 kilometres per hour (190 mph). Not exactly the most forgiving place. With the recent fervor around the possibility of life on mars, fuelled by the landing of the Curiosity rover last summer, no one seems to …

Is the ‘supermoon’ really super?

Just a week ago, the whole internet was getting ready for the supermoon, a full moon that is slightly (ever so slightly) bigger than usual. But there is really nothing special about ‘supermoons’, it’s just an astronomical coincidence that is practically impossible to notice. To the naked eye it does not look any different. What exactly is a ‘supermoon’?

What’s up with Dark Matter?

There’s a lot of confusion and misinformation around the interweb regarding dark matter. Much of it sounds like pseudo-scientific borderline-religious arguments, both from strong ‘believers’ (sorry to use that term but I have heard it used so often in this context) and people who don’t like the idea of dark matter and cling to older/other theories. It is after all I suppose a little like a religious argument, not being able to see it doesn’t necessarily mean it’s not there.

The coldest place in the universe is on… earth

The Boomerang Nebula is located approximately 5000 light years from earth. It was formed by the outflow of gas from the core of a star. This gas is flowing at incredible speeds, up to 500 thousand kilometres per hour (300,000 miles/hr). As gas expands, it cools down, which has caused the nebula to be the coldest point of the universe that we have ever measured, with a temperature of just 1 Kelvin (−272.15 °C; −457.87 °F ), very close to absolute zero. The average temperature of the universe is 2.73 K, as measured using the Cosmic Microwave Background Radiation. (Read our …

GPS and Relativity

You were trying to drive to Melbourne, Australia, yet you ended up in Melbourne, Florida. Apart from somehow being able to drive over water, you also probably mindlessly followed the instructions of a GPS device. Practically ubiquitous these days, the Global Positioning System (GPS) is responsible for the ever decreasing ability of people to use maps and their own orientation.