NEW: Solar features and events from the Heliophysics Event Knowledgebase

The Sun has many different features and events of great scientific interest. It’s useful to be able to catalog those features and measure their properties. By doing so, we can build up more knowledge about the Sun.

The Heliophysics Event Knowledgebase (HEK) is one such catalog. The HEK collects and stores information about many different types of solar feature – active regions, flares, etc, from many different sources around the world. Each solar feature and event can be detected in different ways. Some features and events are detected by people looking at the data, and some are detected by specialized computer vision algorithms.

We’ve taken the information in the HEK and designed a simple interface to allow you to find out what features and events occurred on the Sun at any given time. We’ve organized the information in the HEK by feature/event. You may need to reload to get the latest version which includes the HEK.

HV intro: Screenshot from 2013-07-16 10:18:37

The numbers at the end of each line tell you the total number of features/events of each type on the Sun at that time. You can select any combination of features and events you want (green tick marks), or you can select none. If you’ve selected a particular type of feature/event but the text is faded out, this means that there are none of those particular feature/events at the time you’ve requested. If you browse forward and backwards and time and those feature/events are in the HEK, will display them.

We then break down the total number of features/events by feature recognition method. We do this because different feature recognition methods can give different results for the same feature/event type. You can select any combination of the available feature recognition methods, or you can select none. For example, the active regions on the Sun at this time were detected using two different feature recognition methods:

HV Intro: Screenshot from 2013-07-16 10:19:05

The numbers at the end of each line tell you how many active regions were detected by SPoCA (a computer vision algorithm) and the NOAA SWPC Observer (people looking at the data).

Here’s a typical view of some AIA 304 data with the HEK features and events overplotted.

HV Intro: Screenshot from 2013-07-16 10:29:31

Each of the marker pins corresponds to the feature/event detected by a feature recognition method. Clicking on them pulls up much more information on each individual event. Each of the marker pins also has a small label attached to it with an important piece of information concerning that feature/event. We’ve also extended the movie and screenshot capability so that your selected feature/event markers and labels appear in any movies and screenshots you make.

Finally, in the bottom left-hand corner of the viewer window you’ll see a small image of the Earth. This is the size of the Earth on the same scale as the solar and heliospheric images. This also appears in movies and screenshots of the Sun. Full information on using can be found by clicking the help link at the bottom of the webpage.

The HEK is the result of much work by many different people around the world. We are happy to be able to present data from this great solar and heliospheric resource in

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Users highlights: spectacular prominences

Yesterday the Sun showed off a series of spectacular prominence eruptions that were recorded by many users.
Prominences are relatively cool, dense clouds of plasma that lie suspended in Sun’s magnetic field, sometimes for weeks. Occasionally, they become unstable and they erupt.

YouTube user 38starman posted these full disk movies of the Sun. The first is in AIA 304: this waveband sees plasma at around 50,000 K

and this is taken in PROBA2 173

It is possible that one event may have triggered another. Understanding the connection between separate events is a big part of Solar Dynamics Observatory science.

YouTube user коля павл posted a close-up of the prominence towards the south, this time in AIA 131

AIA 131 picks up temperatures at around 400,000 K, 10,000,000 K and 16,000,000 K. By looking at the AIA 304 images, it seems more likely that the prominence has plasma at around 50,000 and 400,000 K. The hotter temperatures that AIA 131 can see occur in flares, which are much more dynamic events than prominences. This is a good example demonstrating that the images we see can contain features at different temperatures.
Multiple wavebands really help us understand the true temperature of features on the Sun.

Thanks to 38starman and коля павл for sharing these movies!

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Over one million movies created

We’ve reached an amazing milestone thanks to you, our users. Users of and Jhelioviewer have created over one million movies since we started counting them in February 2011. This represents an incredible amount of interest from you – our users – in the Sun and the inner heliosphere. We’d like to thank you for your continued interest in exploring our star and its influence in interplanetary space.

The millionth movie was of one hour’s worth of data from the Atmospheric Imaging Assembly (AIA) on SDO, focusing on this small but fast ejection from the Sun.

This led to a faint and extended coronal mass ejection seen in LASCO C2.

The coronal mass ejection was noticed in many different online catalogs of features and events in the Sun, but the original eruption was not. This is an example of how users are finding events on the Sun which are sometimes overlooked.

Just before the millionth movie, someone made this movie of one week of solar activity. This movie shows many different flares and eruptions of all sizes over the course of a week. Also, about 10 seconds into the movie (beginning around 2013-04-17 16:30 UT), you can see that black edges appear on all sides of the field of view. This is caused by the SDO spacecraft pointing slightly away from the center of the Sun for short periods of time. SDO does this to enable measurements of the AIA and HMI detectors. These measurements are a regular and normal part of running the AIA and HMI instruments, and allow us to keep track of the degradation of the detectors.

We’ll be adding new functionality and datasets to the Helioviwer Project in the next few months. We are committed to making it easy for everyone everywhere to explore the Sun and inner heliosphere, in the way you want. We hope that you continue to enjoy using and Jhelioviewer. If you have any ideas on how we can improve our service, please let us know.

Finally we’d like to thank the many NASA, ESA and JAXA funded organizations that have made the Helioviewer Project possible.


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Coming up: Comet ISON in November 2013

You may have heard of Comet ISON, a comet discovered last year that is currently approaching the Sun. It is expected to be visible in the SOHO-LASCO C2 and C3: from SOHO’s viewpoint the comet enters from the lower right early on November 27 and exits towards the top near the end of November 30 this year.

Path of COMET ISON as seen from SOHO

Path of COMET ISON as seen from SOHO LASCO C2 and C3 coronagraphs.

It will also be visible from the COR1 and COR2 instruments on board both STEREO spacecraft. The SOHO Hotshot webpage for Comet ISON has many more links to more details on the path of the comet as seen from SOHO and STEREO. At the moment it looks like this, as seen by the Hubble Space Telescope. It might be a spectacular sight from Earth. The appearance of comets from Earth is hard to predict because how it looks when it gets closer to the Sun depends on the details of its composition. We’ll have to wait and see!

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Helioviewer Server Technical Difficulties

We are currently experiencing some technical difficulties with our main Helioviewer server. While we work on fixing it, we have moved all services over to our backup server. All normal services should be operating nominally. Please contact us if you notice anything amiss with JHelioviewer services are currently not operational, but we hope to have these up and running as soon as possible. Near real-time AIA and HMI images should be available as usual; streams of images from SOHO, STEREO and PROBA2 should be back to near real-time within 24 hours.

We apologize for the interruption to Helioviewer services, and we thank you for your patience.

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Yohkoh SXT full disk images now available

We are happy to announce the availability of full disk Yohkoh Soft X-ray Telescope (SXT) images on SXT images x-rays from the Sun, and therefore looked at some of the hottest plasmas on the Sun. These data are important in trying to understand solar flares and the heating of the Sun’s corona.

Yohkoh (“Sunshine”) was launched in August 30, 1991, from the Kagoshima Space Center (Uchinoura) in Japan, and was a project of the Japanese Institute of Space and Astronautical Science (ISAS). The scientific objective was to observe the energetic phenomena taking place on the Sun, specifically solar flares in x-ray and gamma-ray emissions.


Yohkoh carried four instruments to detect energetic emissions from the Sun: the Soft X-Ray Telescope (SXT), the Hard X-Ray Telescope (HXT), the Bragg Crystal Spectrometer (BCS) and the Wide Band Spectrometer (WBS). A team from the United States collaborated on SXT, and teams from the United States and the United Kingdom collaborated on BCS.

SXT imaged X-rays in the 0.25 – 4.0 keV range. SXT used thin metallic filters to acquire images in restricted portions of the energy range. We are making images from the thin aluminium filter (thin-Al), and the aluminium-magnesium-manganese filter (AlMgMn) available. White-light images are also available up until November 1992. An example thin-aluminium image is shown below.


SXT could resolve features down to 2.5 arc seconds in size. Information about the temperature and density of the plasma emitting the observed x-rays was obtained by comparing images acquired with the different filters. Flare images could be obtained every 2 seconds. Smaller images with a single filter could be obtained as frequently as once every 0.5 seconds.

Yohkoh ceased operations on December 14, 2001. The SXT images we are making available cover portions of Solar Cycles 22 and 23 (we are currently somewhere close to the maximum of Solar Cyce 24). This historical data allows us to compare current solar behavior to previous solar behavior. Such studies allow us to better understand how the Sun operates on timescales of decades and longer.

Yohkoh SXT images are the first images of soft X-ray data available on We hope you enjoy examining this different view of the Sun on

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Maintenance Complete; Friday 1st February 2013

Maintenance operations on the Helioviewer server are now complete, ahead of schedule. All Helioviewer services should be up and running as normal. We thank you for your patience in the last three days while our maintenance operations were ongoing. Please contact us if you notice a departure from normal services.


Helioviewer Team.

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Maintenance postponed until Friday 1 February 2013

Today’s announced maintenance has been postponed until Friday 1st February. Helioviewer services will be brought down around 1600-1700 UT and will be brought back up no later than 2200 UT. We apologize for any inconvenience this may cause.

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Helioviewer Services Temporarily Down For Maintenance 30 January 2013

All Helioviewer services (, JHelioviewer and the embed functionality) will be temporarily suspended today (30 January 2013) to allow for maintenance of our server. We anticipate that services will be suspended at around or before 1700 UT and will resume again at around 2230 UT at the latest (could be much earlier). We apologize for any inconvenience this may cause.

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SDO maneuvers today

From today’s SDO blog entry:

Today, starting at 1315 UTC (8:15 am ET), SDO will execute the EVE Field of View maneuver followed by the HMI/AIA Flatfield at 1630 UTC (11:30 am ET). During these maneuvers the science data will be interrupted. These maneuvers and last weeks’ Delta-H thruster firing were flipped in the schedule published earlier.

Instruments can degrade in the harsh environment of space, and so it is important to calibrate at regular intervals to make sure that we have the best data available at all times. SDO therefore occasionally makes special maneuvers that enable the measurements to be made that can be used to help calibrate the instruments onboard. Whilst these maneuvers are going on, some of the AIA and SDO images may look unusual.

SDO has three instruments onboard: AIA, HMI and the Extreme Ultraviolet Experiment, EVE. The EVE instrument is designed to measure the solar extreme ultraviolet (EUV) irradiance. The EUV radiation includes the 0.1-105 nm range, which provides the majority of the energy for heating Earth’s thermosphere and creating Earth’s ionosphere (charged plasma). The majority of EVE data are time-series of measurements of the spectral content of solar extreme ultraviolet irradiance, although some low spatial resolution x-ray images are also taken by the EVE Solar Aspect Monitor (SAM) instrument (see the example below). EVE gives us lots of information on the spectral content of the Sun’s radiation changes with time, which is very important for understanding the Earth-Sun connection.


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User highlight: oscillating coronal loop

YouTube and user коля павл uploaded this great example of an oscillating coronal loop

As the movie progresses, you see a small eruption take place. As the eruption starts, you can clearly see the southern base of the loop displace. The loop appears to be released in some way, which shakes the whole loop along its entire length. This event is a great example of a transverse coronal loop oscillation. These were first observed by the Transition Region and Coronal Explorer (TRACE) in 1998. Since these initial observations, many more examples have been observed, by both TRACE and AIA. The mechanism of the excitation of these waves remains hidden, but it can be connected with a blast wave generated in a flare epicentre. For scale, the Earth is roughly the same size as the Helioviewer logo in the bottom right hand corner of the movie.

YouTube and user Txema Mutant also caught the oscillation

although it is much more difficult to see in the AIA 193 Angstrom channel compared to the AIA 171 Angstrom channedl(the dark wavy material you see are motions in a prominence, not the same as the coronal loop oscillation).

Observations of coronal loop oscillations, coupled with a theoretical understanding of how these oscillations behave in the coronal plasma has lead to a new field of study called coronal seismology. Coronal seismology is analogous to seismology on Earth. Seismology is the study of earthquakes and the propagation of waves arising from earthquakes, and can be used to infer properties of the structure of the Earth. Similarly, coronal seismology is used to measure properties of the Sun’s coronal plasma. Using coronal seismology, we can derive the density and magnetic field of the coronal plasma, measurements that are difficult make in other ways.

Thanks to коля павл and Txema Mutant for sharing these movies!

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Total Solar Eclipse, November 13.

A total solar eclipse will be visible in the Southern Hemisphere on November 13.

Eclipse first contact begins at approximately 20:36 UT on November 13 and continues until approximately 23:48 UT on November 13. Live streaming of the eclipse is available at Please go to

for many more details concerning this eclipse. An interactive map is available here.

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Helioviewer services to be suspended due to Hurricane Sandy

Hurricane Sandy is currently approaching the East Coast of the United States. Winds from the hurricane are expected to cause widespread power outages in the next 48 hours (Oct 29-30). Since an unplanned power outage to a server can cause severe damage, we are taking the precautionary measure of shutting down the Helioviewer server. The server will shut down in the next hour. We expect to be back online by Wednesday 31st October EST at the latest, contingent on the weather and the availability of power. We apologize for the inconvenience this will cause.

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No Comments and JHelioviewer Back Online and JHelioviewer are both back online after last week’s outage.

The downtime was caused by a problem encountered while expanding our storage capacity, which has since been fixed.

We are currently in the process of restoring images from some earlier years and as a result certain images may not be accessible over the next couple days.

We apologize for any inconvenience this may cause.

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Technical difficulties with image availability beginning October 16

You may have noticed that we currently do not have any images available, even although the website is up and running. This is because we are experiencing some technical difficulties upgrading our image capacity. We are diagnosing the problem at present, and we will make images available as soon as we possibly can. We apologize for the interruption to our services.

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