Jupiter and Mercury, hiding behind the Sun!

If you are wondering where Jupiter and Mercury are at the moment... they are hiding behind the Sun!

Below is a movie using data from the Lasco C3 insrtument on the NASA/ESA SOHO observatory, during February 2010. SOHO points constantly at the Sun, and so it allows us the see Venus, Jupiter and Mercury following their orbits around the far-side of the Sun.

It begins with Venus leaving the scene towards the left (which is why we can see it now in the evening sky), and then Jupiter moving left to right, and finally Mercury appearing!

Note that Lasco C3 is sensitive to 540nm-640nm wavebands, which is mid-green through to mid-red... so I've changed the usual blue colour to grey-scale (I think true colour would be a yellowish-brown...?).

Note also the 'bleeding' of the bright planets - they are so bright, that electrons over-flow into neighbouring cells on the Lasco-C3 CCDs. Note the the Sun is hidden behind a disk, to ensure that its brightness does not damage the camera.

One less comet in our solar system...

These images taken by the NASA/ESA SOHO solar observatory on 20-21 January 2010 show a comet falling towards the Sun (from the bottom left).

As you can see, the comet does not come out the other side, so... bye bye comet! It must have been vaporised by the Sun!

Comets fall towards the Sun frequently (in fact, SOHO has seen over 1600!), but it's always fun to guess if the comet will survive and come out the other side, or just be so close that they are vaporised by the Sun!

The Lasco C3 instrument on board SOHO works by hiding the incredibly bright Sun with a disk (the silhouette of the disk is at the centre, and the arm that holds it in place goes off towards the top right). This allows the camera to see the fainter gas being ejected by the Sun, without the bright Sun damaging the camera.

However, even the planet Venus (bottom left of centre) is too bright for the camera! Venus is so bright, that it fills that part of the digital camera chip with electronic charge, and that charge spills over to the neighbouring pixels forming the long horizontal line. (in fact, my pocket digital camera does axactly the same if I point it at the sun)

Note also that there is a lot of noise on the movie. That is due to cosmic rays hitting the Lasco C3 camera - it's a harsh place is space, and there is no atmosphere to protect SOHO from the cosmic rays.

Oh, and why blue? Well, why not! Each camera on-board SOHO is colour-coded with a different colour, so astronomers immediately know what camera took the image.

This week's Active Sun

Although we are definitely at a solar minimum, that does not mean nothing is happening!

The sequence of images below, taken by the NASA/ESA SOHO Observatory, shows a small sun spot system moving over the last week, as the Sun itself rotates.

With a lot of imagination, you can half-believe that it looks a bit like a Christmas tree, too!

Merry Christmas everyone!

Activity on the Sun

The Sun has an 11 year cycle of activity, and for the last two years the Sun has been very quiet indeed. Last year had the second fewest number of sun spots - in only 1913 was the Sun less active (see this plot of inactivity).

So it has been nice to see a few sunspots on the Sun over the last few days, as shown in the SOHO observatory image below.

A nice image for sure... But I'm still looking forward a few years, when the Sun will (hopefully!) look more like the following image taken in November 2003!

Quiet Sun

The Sun has an 11 year cycle of activity - and we're currently in a low point. There has not been a single spot on the Sun for 45 days in a row! That means that we are now in the deepest solar minimum for a hundred years (and that we cannot blame the Sun for global warming).

Being that there are no Sun-spots, you might think that it is a bad time to be using a solar telescope - but that is not the case (which is fortunate for us here at Sussex since we have two solar telescopes that are available for schools to use!).

Take a look at this image taken by the SOHO observatory...

Even when the Sun is in a quiet state, jets of hot gas can be seen though a solar telescope. For the latest images, take a look at the SOHO realtime data page.

And remember, never look at the Sun directly since it will damage your eyes. Always use equipment with the appropriate solar filters.