Explore the sun in depth with JHelioviewer
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]
New interactive visualization tools developed by the NASA/European Space Agency (ESA) Helioviewer Project allow scientists and the general public to explore images captured by solar observing spacecraft. Previous posts explained the origins and aims of the Helioviewer Project, and the basics of a Web-based app called Helioviewer.org. This post takes a closer look at a downloadable software application JHelioviewer.
The Web app Helioviewer.org allows you to dip your toes into the water of solar image visualization. JHelioviewer, a piece of software you install on your computer, is a dive into the deep end. It gives you powerful additional tools to create vivid images and time-lapse videos.
When you install and start JHelioviewer, it displays a time-lapse video of the most recent 24-hour set of images available from the Solar Dynamics Observatory (SDO) Atmospheric Imaging Assembly (AIA) at 171 Angstroms. (Read this previous post to learn more about the AIA 171 Angstrom channel on SDO.)
Here are the basic menus along the left of the JHelioviewer desktop. Guidance is also available on the JHelioviewer Wiki Handbook.
In the Overview menu area (top left), use the yellow frame with the little “Bull’s eye” to target the area of the image you want to work with. If you have a thumb wheel on your mouse, use it to expand or contract the size of the frame. Or use the Zoom in and Zoom out buttons on the top navigation bar.
One of the coolest tools in JHelioviewer is Feature tracking. Center the yellow Bull’s eye on a feature and click the Track icon on the top-navigation bar. When you make a time-lapse video, it will hold the targeted feature steady as the rest of the sun moves around it! The software compensates for the rotation of the sun.
This can be especially dramatic if you zoom in close to a feature, like a tangle of magnetic loops, and switch on Track. The feature stays right in the center of the viewer as you watch the magnetic loops dance.
With the More Options tab selected, you can adjust the per-second cadence of your video sequence. The higher the rate, the smoother the video.
Also, there are three play modes: play once and stop; loop forward; or play forward and then backward.
These controls allow you to create sets of solar images to examine, alter, and render into videos. Clicking Add Layer brings up a panel for choosing the start and stop dates, the observatory, the instrument, and the time step between images. The time settings are in UTC (coordinated universal time), which is the same as Greenwich Mean Time (GMT). UTC minus 5 hours gives you Eastern Standard Time.
If you, for example, want to make a video of the past day of solar activity, choose a 24-hour start and stop interval. Now you have to choose the Time Step. Once per hour will make a pretty jumpy video.
So, say you pick the other extreme — once per minute. Unfortunately, you can’t do it, because the system limits you to sets of no more than 1000 images at a time, and there are 1,440 minutes in a day. How about every 10 minutes? Set the Time Step to 2 minutes and you will get 144 images to cover the 24-hour period.
The video you create initially may already look pretty good. But you can use the Adjustments tools to tweak the look of the video and highlight details. Sharpen compensates for fuzziness. Gamma brightens the image. And Contrast increases the differences between bright and dark areas.
Another cool feature: You can make these changes “on the fly,” as your video continues to play. You can also switch AIA instruments on the fly, and frame rate, too, to get the perfect video.
Turning on this feature adds a layer of labels drawn from the Heliophysics Events Knowledgebase. It labels flares, for example, with a special icon. Clicking on an icon makes a window pop up with detailed technical information about the event.
Cool stuff in JHelioviewer
You can create multiple layers and adjust the relative contribution of each using the Opacity control. Layers chosen from the same time period will play in synch.
Another cool feature: Notice in the Layers panel how you can watch the minutes, hours, days, etc. progress as the video plays. I made a 1-year video to browse for times of the year when the sun was especially active, then went back to those periods to grab still images.
For example, set the time to October 7, 2010, and make a video of that day. Do you see a big dark circle cross in front of the sun? That was the moon during a lunar transit.
JHelioviewer does not, like the Web app Helioviewer.org, allow you to instantly share your video to YouTube. But you can download it as an mp4 file (File>Export Movie), and post it manually on your blog, YouTube channel, or other sharing sites.
But watch out for the file size! My 1-year video at 12-hour time steps (627 SDO images) came in at a file size of 127 Mb. To generate a smaller output file, make the “frame size” smaller in the Export dialog settings.
Here is the video I made with JHelioviewer of a year in the life of our star, May 2010 to May 2011. You can do it, too.
Helioviewer.org (Web app)
A collection of video highlights from 2011 (so far) created by Helioviewer.org users.
See a Helioviewer.org video made by “citizen scientist” LudzikLegoTechnics on YouTube.
The Helioviewer Project Wiki
JHelioviewer (downloadable software)
Read a Web feature about JHelioviewer and its capabilities
The JHelioviewer online handbook
JHelioviewer video tutorial on YouTube HD
ESA Web feature about JHelioviewer.
OH AND DID I MENTION? All opinions and opinionlike objects in this blog are mine alone and NOT those of NASA or Goddard Space Flight Center. And while we’re at it, links to websites posted on this blog do not imply endorsement of those websites by NASA.