Archive for category Science

User highlight: filament eruption in AIA 193.

YouTube and Helioviewer.org user muriealdurian just uploaded this video of a filament eruption as seen in AIA 193:

The filament(1) is the narrow dark moving thread in the middle of the field of view. As the movie progresses the filament evolves and eventually erupts out in to space, causing a coronal mass ejection. The material underneath the filament darkens, indicating an evacuation of plasma, that is, the plasma is draining away from that part of the solar atmosphere. These kinds of events happen a lot, and will happen more as solar activity ramps up. Thank you, muriealdurian, for uploading a good example of a filament eruption.

(1) Prominences are filaments seen over the limb of the Sun – prominences and filaments are the same thing, but have different names for historical reasons. Prominences and filaments were first observed in different wavelengths, and so acquired different names. Later, we realized that they were the same thing, but the two names have stuck around in the literature.

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Amazing aurora, as seen from the International Space Station.

This amazing video of the aurora was taken from the International Space Station:

Aurora are caused by the interaction of solar-sourced particles with the Earth’s magnetic field and atmosphere. During times of geomagnetic storms (as has happened recently) the aurora get pushed towards the equator, leading to many more people being able to see them.

This video, and many others taken from the International Space Station can be found here.

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User highlight: comet in LASCO-C2

YouTube and Helioviewer.org user galaxy387 posted the video below showing a comet falling towards the Sun.

LASCO (Large Angle Spectrometric COronagraph) on board the SOHO spacecraft has seen very many comets since it started observing in 1996. SOHO has reported over 2000 comets, almost all of them found by members of the public. Thanks to the many amateur observers that hunt for comets in SOHO data, SOHO has seen many more comets than any other mission (there was another bright comet observed on May 10-11, 2011. A lot of these comets come from the Kreutz sungrazer family of comets. There is an active community of comet hunters, so if you think you’ve discovered one – and it is certainly possible that you may have – please check the latest reports over there. Thanks for sharing, galaxy387!

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User highlight: contracting loops?

Helioviewer and YouTube user otraLoly spotted this interesting active region earlier on today.

Right at the very start you can see that loops on the southern side of the active region appear to contract (a CME and a prominence eruption are occuring). As the event progresses, you’ll notice that two dark areas appear in the coronal moss, outlined by some very bright, and small scale emission, which end up as loop footpoints to the subsequent loop brightening that occurs. This event is interesting for the detail it is possible to see in AIA, particularly in the brightening of the loop footpoints before the main bright loop occurs. Thanks to user otraLoly for sharing this video with users of helioviewer.org!

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Want to know more about the Helioviewer Project?

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Dan Pendick recently posted an excellent series of articles about the Helioviewer Project on his blog, Geeked on Goddard. In five short articles Dan describes many of the different parts of the project, including Helioviewer.org and JHelioviewer. He also discusses some of the technologies that have made all of this possible. If you are interested in learning more about the project and how it all works, you should definitely check out the articles. Also, if you are a science/tech enthusiast I would highly recommend subscribing to Dan’s blog where you can learn more about some of the other cool projects that call the NASA Goddard Spaceflight Center their home.

Topics covered:

Post 1 of 5: Explore the sun on your desktop with Helioviewer
Post 2 of 5: Getting Started with Helioviewer.org
Post 3 of 5: Explore the sun in depth with JHelioviewer
Post 4 of 5: How it works: building the Helioviewer “back end” with JPEG2000
Post 5 of 5: Helioviewer’s future: an Internet for solar image data

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Lots more to see

Yesterday’s spectacular eruptive event was just one example of the amazing phenomena on the Sun and the inner heliosphere. Stuff is going on all the time, like this coronal mass ejection seen by the STEREO mission

A STEREO CME

or this intriguing prominence (the dark wispy shape close to the edge of the Sun’s disk) evolution, spotted just a couple of days ago by the Solar Dynamics Observatory:

We can even sometimes see comets when we look at the Sun:

The 2000th comet

The 2000th comet seen by the SOHO sun-observing spacecraft.


In fact, the SOHO spacecraft has discovered more comets than any other mission. This particular comet was spotted by an astronomy student, Michal Kusiak of Krakow, Poland.

If you want to know more about the Sun and the inner heliosphere, we suggest going over to The Sun Today. There you can find out more about recent solar events, and what caused them. Got a question about the Sun? Then ask a solar physicist over at the The Sun Today.

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Two waves far larger than the Earth.

These videos show some of the larger scale effects of flares on the Sun. In the video, you can see two big eruptions approximately 10 and 17 seconds into the video, from the active region in the lower left.

But look more closely – can you see a wave of coming out of each of these explosions? They are faint, and can be difficult to see, but they are there. These are examples of EIT waves, so called because they were first seen in the SOHOEIT instrument. These waves are thought to be examples of magnetohydrodynamic waves that propagate in the corona. They are truly large waves; for comparison, the radius of the Earth is about 1/100th that of the Sun. By studying these waves we can learn more about the structure and properties of the solar corona. There is also some evidence that these waves have ‘knock-on’ effects on other parts of the Sun, perhaps causing other events at parts distant from the original explosion. Look at the video – what do you think?

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User highlights: a cool loop arcade.

The event below was found and shared by helioviewer.org and YouTube user “LudzikLegoTechnics” – thanks for that! It’s a wonderful example of a cool loop arcade forming and evolving.

Cool loop arcade seen in SDO AIA 304.

What you’re looking at is a bunch of magnetic field lines, forming into loops of relatively cool plasma (50,000 K), at the limb of the Sun. For comparison, the surface of the Sun is around 4500-6000 K, and natural temperatures on the Earth’s surface are around 200 – 340 K.

There are quite a number of things going on here. Firstly, there are two active regions quite close by each other. Secondly, in the movie below (in AIA 171, which sees plasma at around 600,000 K):

Same loop system seen in SDO AIA 171.

you can see that some field lines appear to open up and a small faint eruption takes off. Finally, the loops form, with bright loop tops; it is likely that magnetic reconnection is taking place here. All in all, this is a very good example of just how complicated the activity on the Sun can be; with so much going on, there’s a lot to learn.

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Fast eruption in AIA 171

After many large and interesting events yesterday, the Sun produced this spectacular eruptive event late yesterday.

Fast eruption in SDO AIA 171.

This lead to a coronal mass ejection with a speed of around 2200 km/s, one of the fastest we’ve seen in the current solar cycle. Interestingly, this erupted material had a lot of bright emission in the AIA 171 pass band, indicating bright or dense (or both) material at around 1,000,000 K, which whilst not unusual, isn’t too common either. The bright loops remaining at the surface of the Sun are known as post-flare loops.

A high quality version of the above movie can be obtained here.

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Moon nibbles Sun: a partial eclipse of the Sun by the Moon as seen by SDO.

Today the Moon is passing across the field of view of AIA on board SDO. AIA sees this as a partial obscuration of the disk of the Sun. If you look at an AIA image near 15:00 UTC (March 04, 2011) you can clearly see that a big round object – our Moon – is blocking a portion of the solar disk, and some off disk-emission.

A partial eclipse of the Sun by the Moon as seen by SDO

Moon nibbles Sun: a partial eclipse of the Sun by the Moon as seen by SDO

If you zoom in to the image, you can see that the edge is not perfectly circular. Those are mountains and valleys on the Moon seen in silhouette.

This partial eclipse of the Sun as seen by SDO was expected, since we know the orbits of SDO, AIA, the Sun and the Moon. You can find out more about the eclipses SDO will see (and has seen) by checking out the SDO operations calendar.

As well as being stunning displays of orbital mechanics, partial eclipses of the Sun by the Moon are also very useful in helping us understand the data we are taking with AIA. If you look closely at where the disk of the Moon meets the Sun, you can see a little bit of color is in the dark disk of the Moon. Since we know that the Moon does not emit radiation (and it is not transparent!), the light causing that little bit of color must have come from the Sun. The only way that light could appear to have come from the Moon is due to slight imperfections in the telescope. By measuring how much light leaks from the bits of the image where the Sun is, over to the bits of the image where the Moon is, we can characterize the imperfections in the telescope. And once we have done that, we can use that to improve the images by enhancing the image to take out the effects of the telescope imperfections.

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