It's been 15 years since the magnificent Hubble Space Telescope was sent into orbit. Since then, it's taken more than 700,000 photographs and helped to advance our understanding of the Universe in so many ways. Here's a 1024x768 wallpaper image of just one of those photographs - the Eagle Nebula. It was taken using Hubble's new Advanced Camera for Surveys (ACS).

Knowing where to go involves exploring or using a map. Rather than reinventing the wheel, so to speak, everyone looks at a map when starting a journey. This speeds up their travels and lets them discuss their whereabouts with others. Robin Scagell in his book Night Sky Atlas provides the maps and directions to give the neophyte stargazer a leg up on their understanding of the heavens. So don't go guessing on where to look for which constellation, start with this book then take that first step into astronomy.

Astronomers have seen high temperature "hotspots" rotating across the surface of three nearby neutron stars using the ESA's XMM-Newton X-ray telescope. Even though these neutron stars are hundreds of light-years away, astronomers can calculate the size of the hotspots down to dozens of metres - some are the size of a football field, and others the size of a golf course. The hotspots are somehow related to the stars' powerful magnetic fields, but the exact mechanism is still a mystery.

The devastating earthquake in Sumatra late last year was so powerful that it created a warp in the Earth's gravity field that should be visible by the ESA's Gravity Field and Ocean Circulation Explorer (GOCE) due to launch next year. During the earthquake, the sea floor along the fault line raised up 6 metres (20 feet), shifting the local gravity slightly. Similar shifts in gravity happen when large areas of ice melt, or volcanoes bulge up. By measuring these shifts, GOCE will help scientists understand the forces involved in earthquakes.

This false colour composite image of Titan, Saturn's largest moon, was taken by Cassini on April 16 during its recent flyby. It was created by combining two infrared images of Titan with a visible light image. The green represents places where Cassini could see down to the surface, red indicates areas high in Titan's atmosphere, and blue shows the moon's outer edge. The images were taken when Cassini was approximately 160,000 km (100,000 miles) away.

One of the big hazards for astronauts living on the Moon is going to be the dust; it gets everywhere, and is very dangerous to breathe. Lunar dust is similar to silica dust on Earth, which can cause silicosis, a disease that damages the lungs. Martian dust could be even more dangerous because it is a strong oxidizer - it could actually burn your skin if it touched. Future missions will need to control lunar and martian dust from getting inside spacecraft and habitats, and NASA is working on potential solutions.

New observations from the Solar and Heliospheric Observatory (SOHO) has helped solar astronomers trace the source of the Sun's solar wind. The solar wind is a constant stream of protons, alpha particles, heavy ions and electrons flowing from the Sun. The solar wind had been seen streaming from various regions on the Sun, but scientists have now been able to work out the structure of funnel-shaped magnetic fields that carry material from below the surface of the Sun, and eject it into space.

This image shows nebula N214, a large region of dust and gas located in the neighbouring Large Magellanic Cloud galaxy. The image was taken using the European Southern Observatory's 3.5m New Technology telescope (NTT) located at La Silla in Chile. The central, brightest spot in the nebula isn't a star, but a cluster of stars that add up to about 80 solar masses. The large blob of gas at the top of the nebula probably contains a massive star, probably 40 times our Sun, which is putting out 200,000 times as much energy.

The European Space Agency's Mars Express spacecraft took this unusual photograph of the Aureum Chaos region on Mars. It's located at the eastern part of the Valles Marineris, near a large impact crater called Aram Chaos. The history of this region is very complex. It was probably filled with sediment and then large areas collapsed due to the removal of ice, water or magma; various flat-topped mesas remained.

Japanese astronomers have used the 8.2m Subaru Telescope to get detailed images of the envelope of gas and dust surrounding a very young star in M17. This envelope extends in a symmetrical butterfly shape about 150 times the size of our Solar System. This image hints at the process of how matter streams into the protostellar disc during early formation of a new star.

When NASA's Genesis smashed into the desert last year, mission controllers and scientists feared the worst for the spacecraft's fragile particle collectors. However, after having examined them carefully, it appears that plenty of useful science will be possible with the collected material. The four solar wind collectors, in an instrument called the concentrator are in excellent condition and should help scientists understand how the Solar System formed.

There's a number in the Universe which we humans call alpha - or the fine structure constant. It shows up in almost every mathematical formula dealing with magnetism and electricity. The very speed of light depends on it. If the value for alpha was even a little bit different, the Universe as we know it wouldn't exist - you, me and everyone on Earth wouldn't be here. Some physicists have recently reported that the value for alpha has been slowly changing since the Big Bang. Others, including Jeffrey Newman from the Lawrence Berkeley National Laboratory have good evidence that alpha has remained unchanged for at least 7 billion years.

There's going to be a partial lunar eclipse on Sunday, April 24; unfortunately, the Moon will only pass through the faint penumbral shadow, and only dim slightly. Most observers would be hard-pressed to tell the difference. The eclipse gets going at 0955 UT (5:55 am EDT) and ends about 2 hours later. Observers in the Americas should be able to see the eclipse, with the best view for folks in the West.

The planets in our Solar System formed more than 4.6 billion years ago from cloud of dust and gas that collapsed under gravity. Scientists have speculated that this cloud lasted anywhere from 1 to 10 million years, but new research has pegged that period at 2 million years. An international team of researchers studied a variety of meteorites that had formed just before the planets. One group, called calcium aluminum-rich inclusions are known to have formed early in the solar nebula, and others, called chondrules, formed right at the end - 2 million years later.

Researchers from the University of Colorado at Boulder have uncovered a group of bacteria living in an extreme environment in Yellowstone National Park in Wyoming. The hardy microbes were discovered living inside rocks near geothermal vents, and are regularly subjected to an acidic environment with high levels of metals and silicates and very high temperatures. These microbes can end up as fossils, so scientists can see how they've changed over time, and they can learn additional signs to look for life on Mars.

NASA's Spitzer Space Telescope has discovered an enormous asteroid belt orbiting another star, containing 25 times as much material as the belt in our Solar System. If we had an asteroid belt this thick, it would light up the night sky in a bright band. Once confirmed, this will be the first asteroid belt found orbiting a star similar to our own Sun. Another possibility is that Spitzer is seeing a Pluto-sized comet which has been orbiting the star for many years and has left a bright trail of particles.

NASA's Lunar Prospector hinted at the possibility that there are pockets of water ice in permanently shadowed craters at the Moon's poles. These reservoirs of water would be and invaluable supply of drinking water and air for astronauts, as well as the raw material for propellants. Scientists just need to confirm that it's there. NASA will be sending a new spacecraft, the Lunar Reconnaissance Orbiter, in 2008. It'll have four separate instruments capable of detecting water. So, we might know the answer soon.

Physicists with MIT have reported the discovery of a new state of matter - a perfect liquid - which was probably present in the earliest moments after the Big Bang. The team smashed atoms together in the Relativistic Heavy Ion Collider, creating a plasma that lasted for only an instant. The particles in the plasma have the same properties as a liquid; they cling together and move in a pattern, but they would flow much more easily than water if they could be poured.