Sunspotter in the Classroom

There has never been a better time to help scientists understand the mysteries of the sun. Sunspotter has been steadily making progress classifying images of sunspots for more than a year, and with this week being the first “Sunspotter Citizen Science Challenge”, it is an ideal opportunity to make yourself acquainted with (or revisit) While Sunspotter offers international appeal, giving science enthusiasts across the globe a chance to help us understand solar activity, in Ireland it has gained particular significance. Sunspotter is the first Irish-led Zooniverse project and is a project that helps us strive towards some of the national and international educational goals we have set ourselves as a country. The Irish education system is in a state of transition and one of the most exciting developments is the addition of a new science curriculum that will be offered to Irish students at Junior Cycle level (12-15 year olds). Introducing any new curriculum presents challenges, but one of the most exciting initiatives is the addition of an “Earth and Space” strand. This means that for the first time, Irish students will be learning about the formation of the Universe, the stars and the planets on a formal syllabus at junior level. On a European scale, one of the objectives of the European Commission is to help strive for a society that is more engaged in research, governance and accountability. Citizen science is seen as a method of encouraging young Europeans to become involved in science and to form evidence-based opinions on efficient and transparent uses of public and private science and research funding. All of this has led to Sunspotter being the perfect citizen science project to act as the basis of an educational initiative for Irish schools.

In order for Sunspotter to be utilised as a resource in Irish classrooms it required the support and contributions of a number of forward-thinking organisations. Firstly, it was piloted in Science Gallery Dublin ( This pilot allowed us to see if Sunspotter would work as a classroom activity. It was trialled with pens and paper and the students were tasked with identifying the sunspots in order of complexity (See Figure 1). This was a crude pre-digital version of Sunspotter but it still encapsulated the fundamentals of the project and showed the team that it could work as a larger educational initiative. Secondly, funding was awarded from Science Foundation Ireland ( so that Sunspotter could be brought to schools around Ireland. Members of the Sunspotter team designed the content and learning outcomes of the Sunspotter classroom workshops while PhD students in the Astrophysics Research Group at Trinity College ( were responsible for visiting schools around the country and delivering the workshops. Later in the project, these workshops will be made available as classroom resources at: As well as directly visiting schools, the Sunspotter team brought workshops to a number of science festivals in Ireland, including World Space Week and the Midlands Science Festival (See Figure 2).

Sunspotter was first piloted in Science Gallery Dublin. This was the first look at the project that would eventually live at

Figure 1: Sunspotter was first piloted in Science Gallery Dublin. This was the first look at the project that would eventually live at

Figure 2: Sunspotter workshops took place at Science Festivals like World Space Week, where students not only had the chance to learn how to make comets (left image) they also took part in citizen science workshops (using iPads provided by the School of Physics - middle and right image) where they encountered Sunspotter and several other Zooniverse projects.

Figure 2: Sunspotter workshops took place at Science Festivals like World Space Week, where students not only had the chance to learn how to make comets (left image) they also took part in citizen science workshops (using iPads provided by the School of Physics – middle and right image) where they encountered Sunspotter and several other Zooniverse projects.

Over the course of the year Sunspotter workshops have taken place at schools across Ireland. Almost 20 different locations around the country have been visited. For each school visit, members of the Sunspotter team bring a set of iPads so that the students get a chance to participate in Sunspotter and other Zooniverse projects. They also learn about the merits of citizen science and how their contributions are crucial to eventually solving the mystery of sunspots and their role in warning us about eruptions on the surface of the Sun. More than 500 students have taken part in these workshops so far. Before and after each of the workshops the students fill out a short questionnaire to help evaluate the project, the results of which will be published in a science education journal. It is already obvious that visiting the schools and engaging students with a project like Sunspotter is a worthwhile endeavour. 93% of the students have not heard of Zooniverse before the workshops and 88% have never heard of “citizen science”. There have also been obstacles for the project to overcome. Travelling to workshops across Ireland in rural locations with a suitcase full of iPads is not a straightforward process. Subsequently finding out that the school and surrounding areas do not have as much Internet access as was perhaps thought can also be a challenge to members of the Sunspotter team. Funding for this work is also limited and hopefully more sources will be found over the coming months. Regardless of these barriers, Sunspotter will find its way into more Irish classrooms one way or another. The Sunspotter team will continue to make sure that as many young students as possible have a chance to engage in a citizen science project (See Figure 3).

Figure 3: Sunspotter workshops in the School of Physics in Trinity College Dublin (left image). Astrophysicists Dr Pietro Zucca and Áine Flood visiting classrooms in Co. Westmeath as part of the midlands Science Festival (left image)

Figure 3: Sunspotter workshops in the School of Physics in Trinity College Dublin (left image). Astrophysicists Dr Pietro Zucca and Áine Flood visiting classrooms in Co. Westmeath as part of the midlands Science Festival (right image).

While Sunspotter remains a Zooniverse project, its potential as an educational resource will continue to be explored. Overtime, we hope that the educational opportunities of Sunspotter will embrace the citizen science community as much as the science objectives of the larger project. This week is all about the “Sunspotter Citizen Science Challenge” and as well as helping us classify sunspots and spread the word about Sunspotter, feel free to get in touch with us and talk about your experiences using Sunspotter in the classroom or to share your ideas about how Sunspotter could be used as an educational resource in future. You can get in touch with the team on Twitter (we are @sunspotter_org). Thanks for helping us make Sunspotter a project that we can all be proud of and we look forward to more exciting developments in the future.

Dr Joseph Roche is an Astrophysicist and Assistant Professor in Science Education at Trinity College Dublin. Twitter: @joeboating

Basics of a Solar Flare Forecast

In a previous post I described the concept of space weather. Whilst monitoring current conditions around Earth, space weather forecasters will produce forecasts of the likelihood of solar eruptions occurring over the next few days. Solar flare forecasts are just one part of these daily guidance documents. To create a forecast, a few simple guidelines are generally followed, which I will outline in this post.

1. Setting the scene.

For any forecast, be it Earth weather or space weather, the forecaster needs to begin by describing what is happening now. They start by examining solar imagery, such as the MDI magnetograms used in Sunspotter. They will identify any features in these magnetograms which are already having, or are likely to have, an impact on space weather conditions in the coming days. See Figure 1 for an example of identifying active regions using magnetograms. In this particular example, regions have been numbered according to the NOAA Space Weather Prediction Centre sunspot numbering scheme – when a new region emerges onto the solar disk it is given a number in order. The Solar Monitor Active Region Tracker method outlined in a previous post is another way to identify regions of interest, which automatically produced the data sets you see in Sunspotter.

SDO/HMI magnetogram from 2015 August 22, source:

Figure 1: SDO/HMI magnetogram from 2015 August 22. NOAA active region 12403 might be of particular interest to a forecaster, with a ‘beta-gamma-delta’ classification. Figure source:

The forecaster will examine the history of these identified regions of interest– if something significant has happened recently this might get described in the guidance document, perhaps with images to help the viewer understand what happened and why.

2. What’s likely to happen (the forecast)?

Once the current situation has been described, it is time to move on to what is likely to happen over the period of the forecast. This can be separated into two parts:

2.1 The next 24 hours.

The forecaster will describe in the guidance document how any identified regions are likely to move or develop in the immediate future. For example is a sunspot region growing? Is it complex? Is it likely to produce flares? This is where your classifications in Sunspotter will help define how complex a region is! Once forecasters have decided on a classification, they will calculate the probability of a flare occurring in this region over the next 24 hours.

There are many ways to do this, including Bayesian methods (e.g., Wheatland et al), machine learning (e.g, Qahwaji et al), discriminant analysis (e.g., Barnes et al), and many more. A relatively simple statistical method is often used in operational flare forecasting, which starts with a large database of flare information from previous solar cycles. This database shows how many particular classes of flares each classification of active region produced in that time period. From this an average flare rate can be calculated, and using Poisson statistics a percentage probability of flare occurrence for the next 24 hours will be obtained for each region. See Bloomfield et al, 2012 for a more in-depth description of this method. A little human intervention is also involved here – if a forecaster thinks the value is too small or too big they can change it based on their experience! The percentages for each region can then be added to obtain the probability of a flare occurring across the entire solar disk over the next 24 hours.

2.2 The rest of the forecast period.

The forecaster will then take a briefer look at the whole sun over the next few days. If the next 24 hours look fairly quiet, but something interesting is expected to return to the solar disk in a couple of days time, then the probability of a flare occurring might be increased later on in the forecast period. Similarly if a particularly complex region is due to leave the disk in a few days, the probability might be decreased for that day. An example of a typical flare forecast is shown in Figure 2.

Example of a typical flare forecast for the next four days. Percentage probabilities of M- and X- class flares are included, as well as a description of current conditions.

Figure 2: Example of a solar flare forecast for the next four days. Percentage probabilities are calculated for two ‘levels’ that are related to M- and X- class flares. These are the two largest classes of solar flare, the ones most likely to produce radio blackouts. The forecast also mentions whether any M- or X- class flares occurred over the previous day, and a general description of current conditions. Figure source: Met Office (Crown Copyright)


3. Potential Earth impacts.

Once the forecaster has described what we expect to happen on the Sun, next it’s time to explain how this may affect life on (or in the vicinity of) Earth. For example can we expect radio blackouts? Do astronauts onboard the International Space Station need to postpone any space walks? This will be summarised as part of more general guidance documents, which include forecasts of other space weather phenomena such as coronal mass ejections.


These are the typical steps taken to create a flare forecast. However every day is different, and forecasters can diverge from this method if necessary! Check out current space weather conditions on, e.g., the SWPC and Met Office webpages.


Thanks to Senior Operational Meteorologist, Mark Sidaway, for his guidance when creating this blog post. All statements in this post are my own and not those of the Met Office.


Sunspotter in Traditional Character Chinese!

This post is on behalf of Megan Schwamb, who is currently on the science teams of Planet Four and Planet Hunters. Megan is a postdoctoral fellow at Academia Sinica’s Institute of Astronomy & Astrophysics (ASIAA).

We’re pleased to announce that Sunspotter has been translated to traditional character Chinese. Many thanks to the Zooniverse’s Chris Snyder for getting all the technical things set up for the translation to go live and Mei-Yin Chou at Academia Sinica’s Institute of Astronomy & Astrophysics (ASIAA) in Taiwan for the translating. What follows is an announcement describing Sunspotter in traditional character Chinese and then in English:

太 陽偵查員的目標是決定太陽黑子群的複雜度。大部分的太陽物理學家相信看起來越複雜的太陽黑子群會比看起來簡單的產生更多(且更大)的太陽閃 焰。但是到目前 為止,科學家還找不到一個評量太陽黑子群複雜度的好方法。這對電腦來說也不是個簡單的任務。然而人類卻可以輕易指出兩張影像中哪個比較複雜。

1. 太陽黑子的複雜度是與生俱來的還是經由時間演化造成的?
2. 比較複雜的太陽黑子群會造成比較多的爆發嗎?

在太陽偵查員的第一階段,志工們已經評量超過一萬張太陽黑子群影像的複雜度。這是科學家第一次使用這種評量方式。太陽黑子群的複雜度現在 可以跟其他性質比較,例如大小或總磁通量。而且,這也讓我們發現越複雜的太陽黑子群越可能造成大爆發!

過 去幾個月來,太陽偵查員的第二階段已經啟動,包含了二十萬張太陽黑子群影像。到目前為止,志工們已經做了一百萬個評量!這個階段最終將能 提供我們一個巨大 的資料庫來做分析。除了比較太陽黑子群特性和複雜度及爆發之間的關係,我們也將能得知太陽黑子群出現、越過太陽盤面、最後緩慢消失,這期 間其複雜度的演化 過程。


The goal of Sunspotter is to determine the complexity of sunspot groups. Most solar physicists believe that more complicated looking sunspot groups produce more (and larger) solar flares than simple looking ones. But so far, scientists have not found a good way to quantify sunspot group complexity. This is not a task easily accomplished by a computer. Humans, on the other hand, can easily point to the more complex in a pair of images.

Knowledge of sunspot group complexity will help to definitively answer some of solar physics’ biggest unanswered questions including: 1. Are sunspots born complex or do they evolve to become complex? 2. Do sunspot groups that are more complex produce more eruptions?

In the first round of Sunspotter, volunteers managed to rank over 10,000 images of sunspot groups in terms of complexity. This is the first time that scientists have achieved such a ranking. Sunspot group complexity can now be compared with other properties, such as size and total magnetic flux. Also, this has allowed us to show that more complex sunspot groups are more likely to release large eruptions!

For the past few months, the second round of Sunspotter has been live, and includes 200,000 images of sunspot groups. So far, volunteers have already submitted 1,000,000 rankings! At the end of this round we will have a massive database to analyse. In addition to comparing other sunspot group properties to complexity and eruptions, we will also be able to determine the evolution of complexity with in sunspot groups as they emerge, cross the solar disk, and slowly decay.

…And We’re Back!! Sunspotter Round 2

I suppose Friday the 13th is as good a day as any to launch a Citizen Science project.

For those of you who helped us classify the previous data set: Welcome back!
And hello to all of our new Sunspotters!


If you haven’t a notion of what Sunspotter is all about, check out our science section. In short, our goal is to determine the complexity of sunspot groups. It is well known (to solar physicists) that more complicated looking sunspot groups produce more solar flares than simple looking ones. But so far, scientists have not found a good way to quantify sunspot group complexity. This is not a task easily accomplished by a computer. Humans, on the other hand, can easily point to the more complex in a pair of objects, ideas, images, and so on.

I’m pretty sure you have an idea of which is the more complex: a graduate text on quantum mechanics, or an Italian cookbook?
On the other hand, it would not be straight-forward for a computer to make that choice. The same is true with sunspot groups.

In round one (lasting only a month!), ~1,600 volunteers helped us to rank ~13,000 images of sunspot groups by choosing the more complex one in ~300,000 pairs of images. This has allowed us to quantify ‘true’ sunspot group complexity for the first time! Now that we have a handle on how to give complexity a number, we want to determine how the complexity of a sunspot group changes over time.

A less complex sunspot group.

A less complex sunspot group.

To do this we have automatically detected thousands of sunspot groups and tracked them over time. Each sunspot group has been detected about 15 times per  day. Some of these sunspot groups were included in the previous dataset, but now they are being detected in a different way. That means that you will see a number of similar-looking images- but don’t worry if you can’t tell which sunspot group is more complex, just do your best! When graphing the complexity of a sunspot group over time, we are hoping to see clear jumps in the data when the sunspot group became more complex and we expect this to be followed by the occurrence of solar flares.

A more complex sunspot group

A more complex sunspot group

There are a few ‘biases’ that we could not easily correct for with the previous dataset, that we hope to get a handle on this time. For instance, depending on a sunspot group’s position, it will look more squished as it nears the edge of the Sun. As mentioned in an earlier post, we are now using a projection technique to ‘de-squish’ the sunspot groups. Also, it is likely that the most complex sunspot groups are always the largest. However, humans might also be biased toward thinking bigger things are more complex, even when they are not. So, to help reduce this bias, we have ‘de-scaled’ the images so that all of the sunspot groups, big or small, will appear roughly the same size on your screen.

We think you will find it much easier to focus on complexity with this new data set.

Thanks for listening, and happy classifying!!

¿Qué significa Sunspotter?

Sunspotter es el nuevo proyecto de ciencia ciudadana que nos ofrece zooniverse.  Es el primer proyecto de dicha plataforma que está completamente disponible en español, esto incluye además de la página web, un grupo de científicos de habla hispana que responderán las dudas de los voluntarios y mantendrán este blog con las últimos novedades.

Pero… ¿qué significa Sunspotter?

Para entender el término Sunspotter tenemos que jugar un poquito con el inglés. Muchos de ustedes sabrán que sun significa sol y spot mancha.  De ahí que a las manchas solares se les conozcan como sunspots. Pero en inglés, a veces un sustantivo puede ser también un verbo, y así sucede con to spot que entre otras cosas significa localizar o divisar.  Además, así como to teach es enseñar, y teacher es el que enseña (profesor), spotter es el que realiza la acción de divisar, esto es, un observador. Con esto, conseguimos entender un poco el juego de palabras que deriva del nombre de este proyecto.  Por un lado vamos a clasificar manchas solares, pero por otro, nos beneficiamos de los ojos de los voluntarios que son buenos observadores de la complejidad del sol.

Como ya expliqué en el anterior artículo (donde aún no habíamos logrado la perla de nombre que tenemos ahora), el fin último de este proyecto es ser capaz de predecir cuando las fulguraciones solares van a ocurrir. Sin embargo esta es una empresa para nada sencilla con los datos que tenemos hasta el momento, y es aquí donde Sunspotter intenta incorporar una nueva perspectiva al problema. Durante muchos años los que han trabajado observando el sol y clasificando las manchas solares saben que si una mancha solar es grande, “mala” y “fea” va a producir una fulguración solar. Pero, ¿cómo sabemos si una mancha solar es grande, mala y fea? El tamaño es fácil de obtener mediante un algoritmo sencillo, no así el que sea “mala” y “fea”. ¡Es ahí donde te necesitamos!  Hemos encontrado que la complejidad es un parámetro que nos indica bastante bien cuando un grupo de manchas solares tiene una pinta “mala” y “fea”. Y creemos que con la simple tarea de comparar cuál es el grupo de manchas solares más complejo de entre dos nos da la información suficiente para clasificar todas las manchas solares en esta nueva escala.

No esperes más, ¡únete al resto de voluntarios, y ayúdanos a clasificar las manchas solares!  Entre más seamos mejor será nuestra clasificación.  Tampoco te olvides de preguntarnos en el foro cualquier duda y discutir con el resto de voluntarios tus manchas solares favoritas. ¡Te esperamos!

First Results from Sunspotter

Hello Sunspotters,

After our brief hiatus, we are about to launch the next phase Sunspotter this Friday! As we mentioned before, there will be >200,000 images. Ranking the sunspot group complexity of this new dataset will require literally millions of clicks. This time we are trying to learn about the evolution of complexity in sunspot groups.

Last time, our goal was to obtain a quantitative measure of sunspot group complexity- the results of this are exactly what I presented to the attendees of the 224th American Astrophysical Society meeting in Boston, MA, last week. My talk was well attended by sunspot and solar flare experts who asked a number of insightful questions about the data analysis method, and about how data was presented to the hard-working volunteers.

You can view the slides from the presentation on FigShare. I will be writing an in-depth post explaining the methods and analysis techniques used to get these results as we pull the journal paper together for publication.

Hope to see you all on soon!

Done, Done, and We’re on to the Next One!

The first round of Sunspotter data classification has been completed!

It took around 1,639 registered volunteers (+ an unknown number of anonymous volunteers) 324,465 clicks to compare each image in the set of 12,966 data at least 50 times. So thats an average of 198 clicks/registered volunteer!

Of course in reality, there are those few Sunspotter-aholics that probably did a lion’s share of the work- To everyone that wants to get going on comparing the next set of images, we are working as fast as possible to get the next set of data up!

Example detections using the SMART sunspot group detection algorithm.

Example detections using the SMART sunspot group detection algorithm.

The forthcoming dataset relies on sunspot groups detected by a completely automated algorithm (not relying on human intervention, like the last dataset), called the SolarMonitor Active Region Tracker (SMART; Higgins et al. 2011), and will not be prone to human bias. It will include over two hundred thousand images of sunspot groups. A number of the sunspot groups will overlap with the last dataset, but will be detected and processed in a different way.

As mentioned in a previous post we are using ‘Stereographic Projection‘ techniques to ‘de-smoosh’ the sunspot groups near the solar limb (edge), so that they appear as if they were at the center of the Sun. Stereographic projections are rarely used for images of the Sun (if anyone knows of an example, please tell me!), but they are common in astrophysics). Also, they are commonly used to make maps of the South and North pole of the Earth because although features at the edge of the map become larger by a factor of ~2, they keep shapes the same (the more usual Mercator maps completely distort shape near the poles). Keeping shape the same, or being conformal, is important for Sunspotter, because the shape of a sunspot group is likely to have a big effect on apparent complexity!

In addition to being the first time that anyone has measured the ‘true’ complexity of a large sample sunspot groups, we will now be able to measure the evolution ofsunspot group complexity, and determine how that relates to eruptions.

In the mean time, we will be analysing the previous dataset to determine how complexity relates to other properties of sunspot groups and to solar flare occurrence. Exciting times!

Stay tuned…

A big thank you to all of our volunteers who helped us to complete this awesome dataset!

The Making of a Magnetogram Part I: Lost in a Magnetic Field

Like the magnetic field of a bar magnet (shown here with iron filings), a sunspot group (almost always) has a north and south magnetic pole.

Like the magnetic field of a bar magnet (shown here with iron filings), a sunspot group (almost always) has a north and south magnetic pole. Images courtesy of Newton Henry Black and NASA.

Magnetograms are wondrous things, that when I stop to think about what they are, I can scarcely believe that they even exist! A magnetogram is an image, where color represents magnetic field strength. The idea that you can take a picture of a magnetic field completely goes against my intuition of how magnetic fields work. Prior to studying physics, I only knew magnetic fields as funny forces one feels when pushing/pulling two refrigerator magnets together/apart. How could one possible take a picture of an invisible force!? Well, I’m not going to lie- its not a simple process at all. But I’ll give the explanation my best shot..

I will space out this explanation over a few posts, so I can go into a bit of detail about the whole process- starting from the ‘basic’ physics concepts. …I’ve never met a physics that I thought was basic 🙂

While reading this, if you have any corrections (I’ve never read or written a physics discussion with out at least one mistake) or questions (no matter how ‘basic’ you think they are), please post them in the comments section or on Sunspotter Talk!

Magnetic fields put the ‘magnet’ in Magneto

Magneto using his magnetic powers. Courtesy of James Burns.

I could try and describe magnetic fields in some arcane abstract way, but I will start with something everyone has at least heard of: light… A magnetic field is one component of a light wave; the other component is an electric field. If you remember nothing else from what follows, remember these three rules:

  1. a changing electric field generates a magnetic field; (formally Ampere’s Law)
    …coiling an electrified wire around a magnet will cause it to spin = an electric motor
  2. a changing magnetic field generates an electric field; (formally Faraday’s Law)
    …passing a magnet through a coil of wire will generate electricity = an electrical generator
  3. an accelerating (or decelerating) electric field generates light. (e.g., synchrotron and Bremsstrahlung radiation)

An electro-magnetic (light) wave, showing the magnetic and electric field components. Courtesy of the National High Magnetic Field Laboratory.

And what is light? Incredibly, light is an oscillating electric field and an oscillating magnetic field that perpetuate each other, as long as they travel at the speed of light, 300,000 km/s. This is a constant conversion of electric energy into magnetic energy and magnetic energy back into electric energy. The energy of light is determined by how fast the electric and magnetic field is oscillating. However, in quantum mechanics, light is represented as photons, which are  light-wave ‘packets’ of energy, that behave like particles (e.g., they can bounce off of another particle, like an electron). But in classical mechanics, light behaves as a wave (e.g., two light waves can ‘interfere’ and cancel out or build in strength, just like water waves). The fact that light can simultaneously behave as both a particle and wave is known as ‘wave-particle duality‘. To make a magnetogram, you sometimes have to consider light as a particle, and sometimes as a wave.

Light as a wave. This diagram shows the spectrum of different light wavelengths.

Like a packet of crisps (chips), a photon packet of light is VERY calorie dense. Each photon has a specific amount of energy stored inside. If the conditions are right, a photon can deliver all of its energy to an atom (e.g., a hydrogen atom) by smashing into it. When it does this, the orbit of the electron going around the proton (in a hydrogen atom, for example) will become more energetic, and the photon will be completely absorbed by the atom. This is called photon absorption. On the other hand, an energetic electron in an atom can suddenly (sometimes randomly) become less energetic, and in doing so, release a photon. This is called photon emission, and releases photons at a very narrow range of energies that correspond to the change in energy of the electron’s orbit.

Light as a particle (photon). An diagram of an atom: a nucleus surrounded by orbiting electrons, where one of the electrons has decreased in energy, moving to a lower orbit, and released a photon. This is photon emission.

There is another very different way that light can be released. When anything glows (like a red-hot iron or an old fashioned light bulb) a lot of photons are being released, but in a different way than with ‘emission‘. When something glows because it is hot (like the surface of the Sun), it is usually releasing thermal radiation. When matter has a high temperature, it means that the particles it is made of are moving around really fast, and banging into each other. Remember Rule #3? Every time charged particles in the matter bang into one another, they undergoing deceleration or acceleration, like the balls bouncing around on a pool table, and they release light! Not surprisingly,  the hotter the matter is, the more thermal radiation is being released. It turns out that when something glows at a certain temperature it will release a predictable fraction of its photons at each energy; we can use Planck’s Law to predict this. Thermal radiation releases photons at many different energies (a broad spectrum).

A diagram of intensity (how much radiation is released) at each wavelength for a series of objects at different temperatures. These are blackbody spectra. The peak in wavelength for hotter objects is at a shorter wavelength (more energetic) at has a larger intensity (more light is emitted). The colors are in the reverse order, though: red is actually less energetic than green!

The main thing to remember is this: photon emission releases light in a narrow range of energies, while thermal radiation releases light waves in a broad range of energies.

The theoretical black body spectrum for the Sun (gray) and the actual light spectrum for the Sun (orange). The jagged lines are emission and absorption spectral lines. Courtesy of Charles Chandler.


Proton says to a Neutron, ‘I’ve lost my Electron!

The Neutron says, ‘Are you sure?
The Proton replies, ‘I’m positive!

The surface of the Sun is like an ocean, but instead of being made of water molecules, it is made of (mostly) hydrogen and some helium. Another difference between the solar surface and an ocean is that instead of a refreshing ~290 Kelvin the surface of the Sun is a blazing 5,700 Kelvin (…so hot that it glows yellow!). For this reason, it is a plasma (and not just a ‘gas’). It is a plasma because a significant fraction of the Sun’s hydrogen has been stripped of its electron, leaving just a lonely ionised proton (a positively charged particle), wandering around looking for an electron. This gives plasma some very interesting properties, which will be covered in a future blog post when we discuss the physics of sunspots.

The visible-light solar spectrum; the range of wavelengths of light from the Sun that you can see with your eyes. The dark lines are from photon absorption within the solar atmosphere. Courtesy of Aura.

The Sun isn’t just hydrogen, it also has a small amount of a lot of other elements. These other elements can also undergo photon emission, which produces photons of certain energies. We observe this light as emission lines. By studying emission lines, Helium was first discovered because we saw one of its lines when we looked at the light from the Sun (the name Helium comes from Helios, the Greek Sun god). Atoms or partially ionised atoms (that still have at least one electron) undergo photon emission and absorption all the time because of all the other particles and photons smashing into them.

When atoms or ions undergo photon emission in the presence of a magnetic field, something strange happens. And because of this we are able to measure magnetic fields on the Sun- but you’ll have to wait for The Making of a Magnetogram Part II to hear all about it!

As always if you have any questions/ comments /suggestions, we are eager to hear them!

Thanks for listening.

Space weather – a short guide

I am a space weather research scientist at the Met Office*, the national meteorological service for the United Kingdom. My job is to transition basic research to operational forecasting- in other words, I try to improve space-weather forecasts with new-and-improved science!

What do I mean by space weather? It basically describes the changing environmental conditions in near-Earth space. Magnetic fields, radiation, particles, and matter, which have been ejected from the Sun, can interact with the Earth’s upper atmosphere and surrounding magnetic field to produce a variety of effects.

There are streams of particles from the Sun constantly hitting the Earth via the solar wind, but the Earth experiences an increased impact during periods of high solar activity, when solar eruptions can occur in the form of solar flares and coronal mass ejections (CMEs). Solar flares are sudden releases of energy across the entire electromagnetic spectrum. They are hard to predict, and the energy can be detected in the Earth’s atmosphere as soon as 8.5 minutes after a solar flare (travelling at the speed of light). CMEs are often associated with flares, eruptions of large amounts of matter from the solar atmosphere. These can take days to reach Earth, carrying a local magnetic field from the Sun. Considering the short time frame for forecasting of flares compared to CMEs, it’s really important to have accurate alerts for big events. That’s where your help with Sunspotter comes in – by improving our understanding of the active regions that are the source of flares, we can hopefully improve our forecasts!

A  solar eruption on 2012 August 12 captured by NASA’s Solar Dynamic Observatory in four different extreme ultraviolet wavelengths- clockwise from upper left 335, 171, 131 and 304 Angstrom wavelengths [Credit: NASA/SDO/AIA/GSFC].

A solar eruption on 2012 August 12 captured by NASA’s Solar Dynamic Observatory in four different extreme ultraviolet wavelengths- clockwise from upper left 335, 171, 131 and 304 Angstrom wavelengths [Credit: NASA/SDO/AIA/GSFC].

But why do we care about space weather? In our increasingly technologically-dependent society, the impact of solar eruptive events can actually be quite severe. Some key sectors in need of accurate event forecasts include energy, aviation, satellite operation, marine, communications, rail, and defence. For example, interruptions to radio communications and GPS can occur due to eruptions, and power grids can also be disrupted. Particles accelerated during eruptions can also damage spacecraft and degrade electronics, and instruments often have to be switched-off or reset. It is important for satellite companies to receive accurate information on the likelihood of eruptions to ensure as little down-time as possible. In the aviation industry, flight crews, passengers, and onboard electronics are all under direct exposure to higher levels of radiation on transpolar flights. Even astronauts cannot take space walks during these events. Solar-activity monitoring systems are imperative to keep astronauts safe!

Space weather has several effects on near-Earth space; the most recognisable might be the aurorae at high latitudes. Large solar eruptions can cause aurorae to form in even lower latitudes, as far south as the equator in very strong events. This image shows the aurora australis captured by NASA's IMAGE satellite [Credit: NASA].

Space weather has several effects on near-Earth space; the most recognisable might be the aurorae at high latitudes. Large solar eruptions can cause aurorae to form in even lower latitudes, as far south as the equator in very strong events. This image shows the aurora australis captured by NASA’s IMAGE satellite [Credit: NASA].

There have been a number of events directly related to high solar activity in recent years. For example, during a particularly large event in 1989, the entire power grid of Quebec collapsed, causing a 9-hour blackout which effected 6million people. In December 2006, a powerful flare disrupted satellite-to-ground communications and GPS navigation system signals for about 10 minutes. The eruption was so powerful it actually damaged the solar X-ray imager instrument on the GOES 13 satellite that was taking images of it! An American telecommunications satellite, Galaxy 15, now widely known as ‘zombiesat’, ceased responding to commands in 2010. The manufacturer has theorised that solar activity was responsible for the satellite malfunctioning, although they could not settle on a single root cause. Check out the National Research Council or the Royal Academy of Engineering reports for more information on, and examples of, space weather impacts.

In order to monitor and forecast space weather, we generally use ground-based and satellite instrumentation. The solar surface and atmosphere is observed in near-real time to detect any new active regions that may become the source of large events. These observations, such as the MDI images used in Sunspotter, can help determine whether an eruption may be a threat if it is Earth-directed. The Earth’s atmosphere is also monitored to detect changes related to solar wind variations, as well as short-term impacts of solar eruptions. Ongoing scientific research is crucial to determine the fundamental physical processes involved in driving space weather, such as solar magnetic fields. The more that is known about these processes, the more models can be improved to accurately predict when a flare or eruption will occur. So keep clicking those active regions and help improve our warning systems!

*Disclaimer: all statements in this post are my own, and not those of the Met Office.

Calling all Zoo-ites! Want free access to relevant scientific journal articles?

… Then tell us so!

Why I ❤ Citizen Science

The Sunspotter volunteers have been working tirelessly at classifying all of our sunspot data, and it shows! We are already near 250,000 classifications, making this dataset around 70% completed. After this one is done, we will be releasing a  new dataset that includes over 200,000 sunspot group images, and much more meta data.

Left: a sunspot group magnetogram near the edge of the solar disk. Right: the de-projected sunspot group image, performed using a stereographic de-projection.

Also, we have been experimenting with ways to ‘de-project’ the data so that sunspot groups near the edge or ‘limb’ of the Sun do not appear squashed due to foreshortening- but, more on that when we launch the new dataset…

While working on this project, our team has had the privilege of interacting with some of the Sunspotter volunteers. If you haven’t tried it yet, pop over to and give us a shout! The volunteers taking advantage of Talk have been asking us some fascinating questions about the science behind Sunspotter, why the data looks the way it does, and about our ideas for how the data will be analysed later on. Honestly, it has provoked us to think much more deeply about this project than we would have otherwise.

I think that this is one of the hidden benefits of starting a citizen science project: your grandad’s/grandma’s data analysis algorithm is no longer a lifeless automaton. Now, it is a group of people that can provide you with amazing feedback on the work!

The Cursed Pay-Wall

Over the course of interacting with volunteers on Talk, there have been many discussions about the science behind Sunspotter where a specific research paper came up in the conversation. Unfortunately, many solar and space-physics researchers have not yet discovered the likes of, where you can upload a ‘pre-print’ manuscript of your science journal paper for everyone to read for free. So, often when a Sunspotter volunteer goes to check out a specific paper (perhaps by using the astrophysics-paper search engine, adsabs), they are hit with a ‘Pay-Wall’. If you have not encountered this yet, it occurs when an individual tries to access a science paper on-line, using a computer that is not on a university, research laboratory, or library campus (that has access to the given journal). Often the publisher requires a fee of ~$30 to access a single paper!

It is my personal opinion (and the opinion of many others) that at the very least, the general public (non-working scientists) should be able to freely access any scientific research paper in which the work was paid for by public funding. The vast majority of research is paid for by public money, but the majority of scientific papers published today are not Open Access. On the bright side, there is a growing movement to make science fundamentally freely accessible for everyone.

That said, when a research paper comes up in a Sunspotter conversation, that is not openly accessible, I have taken to emailing the author directly to request that they upload their paper to arXiv to make it available for free. Furthermore, I have begun to email the main astrophysics journal publishers to request that they provide open access to volunteers of citizen science projects. The American Geophysical Union (AGU) has already responded very positively to our request, and is working to provide such access! Furthermore, the folks at Zooniverse got the Monthly Notices of the Royal Astronomical Society (MNRAS) to agree make all citizen science-based research in their journals automatically open-access! Cheers to AGU and MNRAS!

These journals are clearly thinking ahead, and hopefully the other journals will see the light soon!

To help us in our mission of making science more open (especially for citizen science volunteers), please vote in our poll above, to declare your interest (or disinterest) in free access to journal papers. If this is an issue that Zoo-ites feel strongly about, we would like to know. For one thing publishers will take our requests more seriously if we can show that there is substantial support.

Again, we at Sunspotter really appreciate all the time, effort, and interest that you volunteers have given us!