Calendario dell’Avvento:25 dicembre

Look carefully at this animated image. What you see is the Crab pulsar, a rapidly rotating neutron star at the heart of the Crab Nebula, propelling matter and antimatter outward at near the speed of light, seen in 24 sequential images acquired over several months by the Hubble Space Telescope. The Crab pulsar is a tiny, dense remnant of a star that exploded in a supernova, observed here on Earth in the year 1054. It is very small – only about 25 km (15 miles) across, has a mass about 1.5 times our own Sun, and rotates at an amazing rate of 30 times per second. Bright wisps of energetic particles can be seen moving outward from the pulsar at half the speed of light to form an expanding ring. These wisps appear to originate from a shock wave that shows up as an inner X-ray ring. Also, a turbulent jet appears to be spewing material to the left, looking much like steam from a high-pressure boiler – except it’s a stream of matter and anti-matter electrons moving at half the speed of light. This little neutron star, some 6,500 light-years away, has been doing this energetic pirouette for the past thousand years, and, undisturbed, will likely continue to do so for billions of years more. One thing I always want to take away from time spent looking at Hubble images: the Universe is a very dynamic place, even if it can often appear static due to vast distances and scales. (NASA/HST/ASU/J. Hester) More