Explosive or Quiet?

The Sun on your special day | A data-driven solar activity for public events

Visitors explore the sun today and on their special day – birthday, wedding, graduation, you name it – by using heliotime.org and helioviewer.org. Was it active or quiet? Did any explosions occur? When did a really big explosion occur? They can have their favourite picture printed out to take home as a memory of the event.

Heliotime.org is a software developed at FHNW to facilitate search in the heliophysics database of NASA’s software helioviewer.org. It allows users without previous knowledge to identify active and passive periods on the sun, explore timespans of interest in more detail and access stunning satellite images of the sun from 1998 up to today’s latest image.

The activity is an occasion for discussing everything about the sun, as many questions turn up while participants explore our closest star. It is helpful to have scientists and students in heliophysics and/or amateurs knowledgeable in solar science among the facilitators.

The activity has been developed for the Swiss Embassy in London and carried out twice at the Science Museum London on the occasion of their special exhibition ‘The Sun – living with our star’ in winter 2018/2019.

You are welcome to use the activity at your organization or event. If you have any questions, feel free to contact hanna.sathiapal (at) fhnw.ch. Please let us know when you plan to use heliotime.org so we can make sure not to schedule any major updates for this day. And we are happy about any feedback on how your version of the activity went.


The activity is based on two apps linked to each other. Facilitators need to explore the apps in advance to familiarize with their options and be able to support visitors.

Heliotime.org > timeline for finding solar activity

This app needs to be open on the laptops visitors use to explore. For starting the activity, set the screen to full view of the timeline (zoom out).

Visitors can select a timespan they are interested in and zoom in. They can click on the yellow dot to get a preview of the picture of the particular time. If they want to explore it in more detail, they can switch to helioviewer.org by clicking on the ‘view on helioviewer.org’ button.

Helioviewer.org > software for accessing solar data and exploring images in detail.

This app opens when visitors click on the ‘view on helioviewer.org’ button in heliotime.org. Visitors can zoom into details of solar activity. It is nice to explore the solar limb by drag&drop. Advanced users can also change the settings in the menu in the left sidebar.

When a visitor is done exploring a facilitator needs to set the screen back to heliotime.org so the next person can get started. 

Floor plan

List of materials


– big screen or wall for (back-)projecting video loops of solar activity
– projector and stand
– 1 laptop for projection
– computer screen for displaying the Sun today (helioviewer.org)
– 1 laptop for screen
– 4 laptops + mice/pads for visitor exploration (heliotime.org)
– 2 photo printers (we use Canon Selphy CP1300), lots of special photo paper, (pens, stickers)
– 2 laptops for printers with printer software installed
– many plugs and extension cords
– wireless internet for all laptops
– 3 tables
– for fun: artificial orange coloured long hair fur for covering tables
– ~ 16 stools (we find them more handy than chairs)
– instruction leaflets (enough for some visitors to take them home)
– labels
– banner

Video suggestions for projecting on a large screen or a wall (NASA)


Find the most beautiful videos of solar activity on NASA’s YouTube channel searching for ‘sun’. Here are some of my favourites: