beautiful nebula

Located 8,000 light-years from Earth, the Eta Carinae star system is captured in this stunning infrared image from NASA'S Spitzer Space Telescope.

From a cosmic crash to a mini-eclipse—see our favorite photos from space:http://on.natgeo.com/14NNNly

Solarflares from our active Sun

This year our Sun is very active. It is in it's most active part of it's cyclus and that means regular solarflares that are a lot stronger then ususal.
Once every eleven years the magnetic poles of the Sun change place, causing a low magnetic field. This allows more and stronger explosions on the surface of the Sun, called solarflares. If a solarflare is strong enough it can cause probems on Earth with electricity and radio since the flares send electro magnetic radiation into space.

Solarflares are classified into three categories. The C category is the weakest and will cause no problems on Earth where the M category can cause radio problems around the poles. The X category is the strongest and if the outburst is pointed in the direction of the Earth it can cause problems.
The Sun always has small solarflares that never reache the surface of the Earth but can cause the beautiful aurora above the poles. This year however it will reach it peak in activity and already in May it produced three solarflares of the X category. Also in July a strong solarflare was registered by the NASA.
So far the solarflares have caused no problems and come nowhere near the strength of the worst solarflare ever recorded in September 1859. That one was visible with the naked eye and caused chaos, in these times where we have become so dependend on electricity and devices the effect would be even greater.
Let's hope this cyclus will pass again with a minimum of disruption.

A short history of astronomy

Astronomy is the oldest science by far. As long as mankind exists we have looked up to the skies and wondered what was out there. Almost every culture throughout history has studied the Sun, Moon and stars, and watched how celestial bodies move across the sky. For early civilisations, like the ancient Egyptians, astronomy was a way to keep track of the changing seasons. They used it to know when it was time to plant and harvest crops and it was used to make calendars and sundials to keep track of time. In 1000 BC, Indian and Babylonian astronomers had already calculated length of a year as 360 days (which resulted in a 360 degree circle, with each degree representing a solar day). Later the ancient Egyptians refined this calculation to 365.25 days. The most important discoveries

What are constellations?

The first constellations were patterns of stars that ancient peoples used for navigation, timekeeping and storytelling. Most constellations used now, stem from patterns recognised by ancient Greeks and Romans, and they carry myths and legends from that time. However the ancient Greeks were not the first to recognise patterns. The 47 constellations they used were introduced by a Greek astronomer called Euxodus, who had learned them from priests in Egypt. They in turn had adopted them from Babylonian culture and they were originally created by the Sumerians around 2,000 BC. The oldest surviving star catalogue dates from

Brightness and magnitude of stars

If you look up to the sky you see stars with different brightness. Some stars are very bright, while others are just faint. This is partially because some stars are more luminous than others, but also because some stars are much further away than others. For an example have a look at the two pointers of the Southern Cross for instance. Alpha Centauri (the one the furthest from the Cross) seems brighter than Beta Centauri, also called Hadar (the one closest to the Cross). The reason for this is its proximity; it is in fact our closest stellar neighbour. The double stars in Beta Centauri are much more luminous than the triple stars in Alpha Centauri, but they are about 120 times further away. This causes the star to look less bright because the light is spread out over a much larger area as it travels away from the star.

Absolute Magnitude
To compare how stars would look if they were all at the same