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What colour is the universe? April 30, 2011

Posted by Marie in Astronomy, Jodrell Bank, Nebula, Planetary Nebula.

In a long and convoluted story, my last post about the new Jodrell Bank Discovery Centre led a Twitter friend to look at my favourite images page.  This then resulted in a twitter-sation about why the images are so pretty!

The colours in the images are ‘false’; that is,

Credits: Raghvendra Sahai and John Trauger (JPL), the WFPC2 science team, and NASA

if you were to actually be able to travel to see the galaxies or nebulae with your own eyes, you wouldn’t see the colours which are in the images, because our eyes don’t register them.

So I discovered that the people who take the pictures get to choose the colours!

It’s all to do with the chemicals which are detected in the objects, and their wavelengths.  Red indicates the longest wavelength and blue the shortest, with the other colours somewhere in between.

Cats Eye Nebula Credit: NASA, ESA, HEIC, and The Hubble Heritage Team (STScI/AURA) Acknowledgment: R. Corradi (Isaac Newton Group of Telescopes, Spain) and Z. Tsvetanov (NASA).

But however they decide on the colours, they look lovely anyway! Keep an eye on the favourite images page, because I’m adding more all the time. Or if you like, feel free to send me your favourites and I’ll add them to the page.

Crab Nebula March 23, 2011

Posted by Marie in NASA, Nebula, Neutron star, Wonders of the Universe.
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I was watching the third episode of Wonders of the Universe on BBC 2 on Sunday evening, and adored the images of the Crab Nebula, and of the neutron star rotating at its centre.

Image Credit: NASA, ESA, J. Hester, A. Loll (ASU)

The Crab Nebula is the result of a supernova (a star exploding), which was seen on Earth in the year 1054.  It is around 10 light-years across.  In its centre is a pulsar: a neutron star as massive as the Sun but only the size of a small town.  The Crab Pulsar rotates about 30 times each second, and if you’re interested in what that actually sounds like, well here it is.

The television programme also contained images of the pulsar itself – although these are not exactly the same images as used in the programme, this video shows it just as well.  The blue images are in X-ray light, taken by the Chandra X-ray Observatory, and the red images are in optical light from the Hubble Space Telescope (credit: NASA/HST/CXC/SAO).

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