ST
Solar-Terrestrial Sciences

Solar-Terrestrial Sciences

How do we study the magnetosphere?

How do we study the magnetosphere?

Our closest star, the Sun, is constantly emitting hot gas in all directions as its upper atmosphere, the corona, expands. This is known as the Solar Wind, also carrying with it an embedded magnetic field, the Interplanetary Magnetic Field (IMF).  The IMF originates  at the Sun and forms an enormous spiral throughout the solar system as the solar wind escapes radially, while the magnetic field-lines are anchored to the rotating Sun. This is the large-scale environment, or the laboratory, for a magnetospheric physicist. The core of magnetospheric physics is to increase our understanding of the complex interactions occurring when a magnetized planet is exposed to this solar wind and IMF environment. This blog-post will briefly mention some of the ways we study this interaction, and what kind of questions we try to answer about the solar wind – magnetosphere system.

First of all, what is a magnetosphere? A magnetosphere is the region around a magnetized planet where the magnetic field is the one related to the planet itself. The other magnetic domain is the one only connected to the Sun or solar wind, referred to as the IMF in this context. As for the Earth, the boundary between the Earth’s magnetic field and the IMF field-lines is rather sharp. On the dayside, this boundary, known as the magnetopause, usually sits at about ~10 Earth radii toward the Sun at the subsolar location, and wrap around to form a blunt surface that define the magnetosphere, as seen in the image above, forming a long tail in the anti-sunward direction.

When the solar wind and the IMF interact with the magnetosphere a variety of processes take place. Most interesting – when it comes to energy and momentum transfer into the magnetosphere system –  is the magnetic interactions, initially taking place at the dayside magnetopause. Through a process known as magnetic reconnection, field-lines initially connected only to the planet can merge with the incoming IMF to form field-lines magnetically coupled both to the planet and to the Sun/solar wind. This allows these newly opened field-lines to be pulled tailward by the solar wind, while still being anchored to the Earth. This is how most of the solar wind energy enter the magnetosphere system, which could reach values of Terra Watts during geomagnetic storms. A consequence of the dayside reconnection process is that the reservoir of field-lines connected only to Earth is continually reduced. The magnetosphere’s way of solving this problem is through creating new field-lines that have both their footprints anchored to the planet, again through the process of magnetic reconnection. This happens deep within the magnetotail, and causes momentum and energy to be transported toward the planet, responsible for a variety of phenomenon that we can see and measure on the ground at Earth. Most notable are the aurora borealis and -australis visible in bands around the magnetic poles, and associated magnetic disturbances. Interestingly, the entry of the solar wind plasma (particles) itself into the magnetosphere is not very important in describing the aurora. The accelerated particles causing the aurora largely originate from within the system although their energy come from the solar wind.

Nighside aurora seen from the EISCAT Svalbard radar site. Credit: Jone Peter Reistad.

When studying the magnetosphere, a large variety of instruments are being used. One can distinguish between two types of measurements that complement each other, to a large degree. To measure the influence from a large region of the mangetosphere simultaneously, remote sensing techniques are applied. One example of such is observations of the aurora, where the light originate from the high latitude ionosphere at typically 100-200 km. Since the magnetic field at high latitudes map out to very large regions of the magnetosphere, the aurora can be interpreted, to some extent , as a screen illuminating the more distant magnetospheric processes. Therefore, by studying the high-latitude electrodynamics close to the ground, one can infer properties of the much larger magnetosphere. The other type of measurements is in-situ observations of physical quantities such as electric and magnetic fields/waves and charged or neutral particles. This is usually obtained from satellites orbiting within the magnetosphere. One major challenge when interpreting such data in terms of the big system is that they only provide point measurements in a huge system. Also, temporal and spatial variations are in general mixed, as stationary is difficult to obtain/determine. Hence, remote-sensing and in-situ measurements addresses different spatial scales and often different processes in the magnetosphere system, and act  complementary to each other in order to obtain increased knowledge of how the system works. Recent missions that has greatly contributed to increase the understanding of the solar wind – magnetosphere – ionosphere interactions include Cluster, THEMIS, Swarm, Van-Allen Probes, and MMS.

Although we have learned a lot, especially through the space age, of how the solar wind and IMF environment affect the mangetosphere, many questions still remain. One example is the very nature of the reconnection process, which is a fundamental plasma process allowing efficient energy transfer into the system. A dedicated mission, the Mangetospheric Multiscale Mission was recently launched to investigate its details by probing the reconnection region at finer spatial scales than ever before by 4 closely separated spacecrafts. At present, most models describing the large-scale distributions of the important parameters in our system are indeed very static. We know that the reality is highly dynamic and structured, and it remains as an outstanding challenge to further enhance our understanding of the complexities in our system to be able to more accurately predict the outcome of the solar wind – magnetosphere – ionosphere interactions.

Dr. Helen Mason – Solar space missions: a life with the Sun

Dr. Helen Mason – Solar space missions: a life with the Sun

In the December issue of Life of a Scientist we have an interview of Dr. Helen Mason. She was working at the Department of Applied Mathematics and Theoretical Physics at the University of Cambridge, UK until recently when she retired. Her research interests include UV and X-Ray spectrum of the Sun. She has also devoted a lot of time in promoting science and working with schools from all over the world. Retirement for her means “more time for outreach and work with schools”. She has been awarded the OBE (Order of the British Empire) for her public service.

Dr. Helen Mason, OBE

What got you interested in solar physics?

I had an interest in astronomy from an early age. As a small child, I can remember looking up at the night sky with wonder. I studied physics and astronomy at university (Queen Mary College London), and did a topic on the solar wind for my dissertation. I found it fascinating. I was lucky enough to get a PhD place with Prof Mike Seaton at University College London, UCL, to study atomic physics and solar eclipse spectra.

What was your personal drive behind creating the CHIANTI atomic database which is widely used by the stellar and solar physics communities?
CHIANTI is an atomic database setup to calculate spectra from astrophysical plasmas

My expertise is in spectroscopy and atomic physics. I have calculated a lot of atomic data for the coronal visible, UV and X-ray lines. I realized that it was not easy for the solar community to access and use all these data. Ken Dere, from the USA, Brunella Monsignori-Fossi, from Italy, and I met for lunch at a solar physics conference in Italy, and we decided to make atomic data freely accessible online with a user-friendly interface. We decided to call this package CHIANTI, because we all love Italy. Sadly, Brunella died prematurely, but others have joined our team. CHIANTI was first launched over 20 years ago and is regularly updated and improved. We are very proud of our achievement, and very happy that it is used so widely.

As an expert in solar space instruments, having worked on pioneering projects from the Skylab solar observatory to Hinode, what is the one instrument that you would like to see in space in 10 years’ time?

It has indeed been an honour to work on so many wonderful and exciting solar missions, with so many fantastic teams from the UK, USA, Europe and Japan. We have learnt so much about the Sun and the solar atmosphere, but we are still lacking a few pieces of the jigsaw. Of course, I love spectroscopy and what I would really like to see is further developments of complex instruments which combine spectra with high cadence imaging of the solar atmosphere. We’ve had a few examples already, with the early HRTS rocket instrument, and more recently with the superb IRIS solar observations. I’d also like to look again (as we did with the Solar Maximum Mission) at the soft X-ray wavelength region. We could then really get to grips with linking the theory and observations.

A lot of women in science are forced to make compromises between career and family. Did you have to make such a choice? And is there something you would have done differently given another chance?

Combining a career in science with family commitments is never easy, for a male or a female. I have been fortunate that my husband and the people around me have been very supportive. When I was working on SMM at NASA’s Goddard Space Flight Centre, my small children came with me. I was lucky that my sisters were keen to help out and have a free holiday. My solar colleagues have been hugely supportive, with words of encouragement when times looked bleak. I owe so much to the support from senior people (males and females) who believed in me and my abilities. I chose to work part-time for many years. This was a good decision, but not everyone recognizes that working part time does not indicate a lack of commitment, far from it. I have been invited to apply for Professorships at other UK universities, but this was not logistically possible with a family. I don’t regret my decision to stay in Cambridge. It is a wonderful place to live and work.

The OBE is indeed a great honor, in what way did this affect your –daily life –professional life?

The award of the OBE was indeed a great honour, but more so because someone had written a citation for me. You never know who or what they wrote, but the fact that someone did this, touched me deeply. It gave me more confidence in myself and the unconventional path I have trodden. Most of my peers (male and female) are now Professors. I probably could have been too, if I had made different decisions, but I have to say that very few of my peers have an OBE. It is awarded for ‘service’, and this means a lot to me. My OBE was awarded for services to higher education and women in STEM, which makes it very special. In addition, I was awarded it by the Queen at Windsor Castle, a place close to where I grew up.

You have worked extensively with young children and with graduate students. Which group do you prefer to work with? And do you notice a “generation gap” between these two sets of students?

I have indeed worked both with University students and school children. I have had several graduate students, have taught undergraduates. I am also a Life Fellow of St Edmunds College, and was a tutor, then Senior Tutor, so I have supported many students in different faculties, from all over the world. I still keep in touch with some, which is a great joy. 

I have worked with school children in the UK, South Africa and India. I lead the Sun|trek project (www.suntrek.org) which has been highly successful. Working with graduate students and with children is of course very different. I enjoy both. Yes, of course there is a generation gap. Children are now growing up in a very high-tech, consumer dominated world, where ‘celebrity’ is all about getting on a TV reality show. The pressures on children these days are immense, and many are suffering with bullying, depression, eating-disorders etc. This is a huge responsibility for our society.

As a woman of so many accolades, what was the one thing in your career that you consider a triumph but never got the acknowledgement you deserved?

Career-wise, I don’t seek accolades, but I do like the work I have done to be acknowledged. I have had a few significant press releases, and participated in media activities, radio and TV. I don’t think I have a ‘triumph’ which never got the acknowledgement which I thought it deserved.

It’s been a long fight for the cause of women in science, a fight that is far from over. Specially in some fields. What do you think about the drastically varying percentage of women in some fields Vs others. Are there lessons we should learn and use to improve things across the board?

Well, I think I could write a whole treatise on this topic. My view is that everyone has their own path to tread, all equally valid. The main issue is with perceptions, and this requires a cultural change. We do not all need to follow the same ‘standard’ career path. This is not an issue which just concerns women. I know men whose careers are suffering because of family commitments or other responsibilities. For couples in a relationship, a major issue is one of mobility, that is they need to find positions in the same location. This rarely happens, and one partner often has to compromise, possibly surviving for many years on ‘soft’ money. Males can find it equally hard to get funding and grants after a certain age, no matter how good they are. Technology should make it much easier to work remotely, which should make life easier, but doesn’t seem to yet. Part-time working or ‘time off’ still counts against you in job selection and promotion. Having a family is a commitment, which needs to be recognized. A work/life balance is important for males and females in our society. Attitudes need to change at the highest levels to provide more flexibility in our working patterns.

What is life after retirement?

I am still waiting to see what ‘life after retirement’ will be like. I hope to focus more on the things which I find fulfilling, my research and outreach work. I hope to start some new ventures and have more time for my family and friends. This is the theory, but I have not yet been able to put it in practice! I intend to do my solar research, and to be involved in future projects. I am also keen to link science and art. I lead an STFC funded project ‘SunSpaceArt’ which takes scientists and artists into schools. The children have produced some fantastic, creative and imaginative work. It is very rewarding to see how animated they get. I believe that STEAM, STEM with Art, is a good way forward for the future.

Helen doing what she loves. Right: with family, Middle: DAMYP Astro group at (Faculty of Maths) Open Day and Left: working with students in India

EGU for Early Career Scientists

EGU for Early Career Scientists

Are you a student, or have obtained a MSc or PhD degree within the past 7 years? If yes, you are an Early Career Scientist! In the EGU we take great care of the young scientists, and offer a wide range of opportunities, mostly associated with the General Assembly. My name is Jone Peter Reistad and I am the Early Career Scientist (ECS) representative in the Solar-Terrestrial division. My role is to make the ECS aware of the opportunities and activities that EGU offers to the scientists of the future, as well as engaging in creating and shaping the ECS venue.

The purpose of this blog-post is to draw your attention to the upcoming General Assembly in April next year. This might sound distant, but you should definitely start thinking about this now! Let me explain why: first of all, the EGU General Assembly is a special meeting for ECSs. Actually, more than 50 % of the meeting participants are covered by the ECS definition. During the last years there has been an increasing effort to make the General Assembly more relevant for ECS. There are numerous Short Courses addressing practical skills (both general and more division specific), hot topics, and other challenges that ECS face. Furthermore, social events such as the icebreaker reception, a networking reception, and the ECS forum, are held during the week. For these reasons, the EGU General Assembly is a highly relevant, and in my opinion outstanding meeting for Early Career Scientists to attend.

But why consider going to EGU now? The regular abstract deadline is January 10, however, if you send in your abstract by December 1st, you can apply for Early Career Scientist’s Travel Support. This will potentially cover your registration and abstract fee in addition to travel expenses up to 300. December 1st is only a few weeks ahead, so do not hesitate to submit your abstract and apply for travel funds.

Of special relevance to our Solar-Terrestrial ECS readers is a Short Course we will run now for the fourth time: “Meet the Experts: The future of Solar-Terrestrial research”. Being an Early Career Scientist, it is often hard to identify which questions are new and what has been answered before. In this short course we invite a panel of renowned researchers. They will give their view on how far we have come in our understanding, and most importantly, on what challenges lie ahead for the young scientists to embark upon. This is an excellent opportunity to meet with the experts and discuss the future of our community.

We are currently a team of 5 people involved in making the Solar-Terrestrial division, especially the General Assembly, more relevant for ECS. If you have any ideas to what could be done, or want to contribute in any way, please send me a notice to ecs-st@egu.eu.

Eyes on the Sun

Eyes on the Sun

The Sun is a complex, dynamic ball of plasma which influences our lives. Studying the Sun is challenging because each of its layers have different composition, physics and wavelengths of emssion. Moving outwards from the photosphere (visible surface of the Sun), we have the chromosphere and the corona (hottest outermost layer). The solar plasma is in constant motion much like fiercely boiling water. To make matters worse, gigantic planet sized eruptions frequently play havoc with space-based instruments and communications.

To understand the workings of the Sun, solar physicists look through the eyes of 21 ground-based telescopes, 8 space-based observatories, dozens of radio telescopes, X-ray detectors, and many high altitude platforms that collect particles emitted by the sun. Optical astronomy, spectroscopy and magnetic field measurements are the most common techniques used.

The most common ground-based observations are taken with Hydrogen-alpha and Calcium-II filters. The Sun’s chromosphere is abundant in these elements/ions and emits light in these wavelengths. Chromospheric features such as spicules, prominences (i.e., jets, protrusions of plasma respectively) etc. are studied using these observations. The Sun’s hot corona emits light in UV and EUV wavelengths. Since emissions in this range are absorbed by the Earth’s atmosphere, we rely heavily on space-based observatories to study coronal loops, flares etc. The variety of structures on the Sun and the different layers of the Sun are abundant in specific elements/ions. The stunning images from different filters (see fig 1) provide unique ways to probe the depths of our amazing Sun. Simultaneous images from the 9 filters onboard NASA’s Solar Dynamics Observatory has been revealing secrets of our dynamic Sun since 2012.

Optical telescopes are easy to build but only give us the overall view of the Sun. The temperature, ionization state, density, magnetic/electric fields, speed/direction of motion all influence the emission from a particular plasma. We require spectroscopic data to extract this information. Spectral profiles can also give us indication of unresolved structures. The latest spectrograph in the sky is NASA’s Interface Region Imaging Spectrograph. Although spectrographs provide a large dose of information, they are limited by field-of-view and downlink bandwidth. Scientists therefore need to compromise on the number of wavelengths or area of observation when using spectrographs, restricting their progress.

Fig. 2: Composite image showing multi-temperature plasma. Cool 60,000 K plasma in red and hot 1 MK plasma in blue and green Credits: NASA/GSFC/SDO

The Sun’s 22-year magnetic cycle is another mystery pending to be solved. Manifestations of the magnetic field result in solar activity. Unambiguous measurements of the magnetic field are currently possible only in the photosphere. Scientists are engaged in developing indirect techniques to measure magnetic field in the higher solar atmosphere. Solar Orbiter, joint venture by ESA and NASA, will, for the first time, clearly measure the magnetic field strength near the poles of the Sun. This will improve solar models and advance our knowledge of the solar dynamo and the reversal of the global magnetic field.

Learning about the Sun will not only enhance our capabilities of predicting space weather, which can disrupt our daily lives but also strengthen our knowledge about other stars. The Sun is our closest star and we cannot study any other star in as detail as we can the Sun. Studying our “Sun as a star” will help us extrapolate the knowledge to other stars. How stars interact with the worlds around them is a relevant topic in sight of the search for extra-terrestrial life. We could also determine what will become of our planet and us eventually.

Miho Janvier – The Quest for Solar Storms

Miho Janvier – The Quest for Solar Storms

In this month’s (first ever for our blog) Life of a Scientist interview, we are very happy to talk to Dr Miho Janvier, a Researcher at the Institut d’Astrophysique Spatiale in Orsay (France), whose work has shed some light on the understanding of solar eruptions and coronal mass ejections  (or solar storms) from their birth in the Sun’s corona to their evolution in interplanetary space. Additionally, Miho has actively taken part in Educational & Public Outreach efforts and has co-created an outreach project on Solar Storms using Virtual Reality technology.

 

Miho, can you please say a few words about yourself?


Miho Janvier (Credit: Miho Janvier)

I am currently working as an associate astronomer at the Institut d’Astrophysique Spatiale in Orsay (France). My main research interests are the understanding of the fundamental mechanisms of how solar flares occur, and how to better characterize the solar storms they send in space. My research work is quite varied, as I get to work with computer simulations as well as space mission data, and for the analytical part, it’s back to pen and paper! I am also involved in the next European Space Agency mission to the Sun called Solar Orbiter: with the team at my institute, we are responsible for the operations that will be carried by one instrument (SPICE) onboard the spacecraft. I also teach at the University and am involved in outreach projects.

What is a “typical” day in the life of a scientist? Describe one of your “usual” days.

It is difficult to describe a usual day because every day happens to be completely different from another! When I am not at a conference, I generally check and answer the most pressing emails in the morning, while my favorite tea is brewing. I would generally dedicate a few hours for research before heading to lunch with my colleagues. I love these moments of socializing, as the rest of the day can be spent alone in front of a computer! Depending on the days, I may have a meeting in the afternoon, either to discuss the preparation of operations on our instrument for the Solar Orbiter mission, or to discuss new outreach projects, or to dedicate some time for the lab communication team, in which I am involved. This is also the time I answer emails that need a longer thinking time.

What do you want to achieve with your research?

First of all, satisfy my inner curiosity about the universe! This is the one reason I wanted to become an astrophysicist in the first place. Funnily, the more research I do, the more questions I have. It is a never-ending process. On a more practical level, I want my research to matter for different reasons. First, to better understand what it means to live in the neighborhood of an active star that is the Sun. Secondly, not only will this help us to build the tools for space weather forecasting that are important for human societies, it will also help us understand how planets in the solar system react to the Sun’s activity. And ultimately, this research will help assess the conditions of life in other star systems too.

Why did you become a scientist and what drew you to this field?

As a child, I was always fascinated by the night sky. But it is not until I turned 9 and discovered the TV show X-files that I became a big fan of aliens. It may sound weird, but that was my first motivation for becoming an astrophysicist! Of course, the word “aliens” may sound like a joke, but in the bigger picture, what I mean is that questioning the existence of life in the universe is, to me, one of the most fascinating questions in life.
Later in my studies, I really liked the aspect of plasma physics, where the behavior of an ionized “fluid” is affected by an electromagnetic field (and I did like working with Maxwell’s equations). I finished my PhD in plasma physics as the space telescope Solar Dynamics Observatory was in its first mission years, sending us extremely detailed images of the Sun and its beautiful eruptions.  It just seemed natural to turn to solar physics!

 

What advice would you give to your younger self?

To be more confident about yourself, and for this, to build a support network along your career. A few years ago, I came across the expression “impostor syndrome” and realized that the pressure we have, as young scientists, can be daunting. As a woman in science, I also realized along the years that there are still a lot of stigmas and unconscious biases in science that can make you feel like you don’t belong to the field. Creating a network of colleagues, friends (and the two can intersect!) and self-care routines will help you go through the times when you have doubts.

What do you consider as the most surprising result in your research so far?

A few years ago, with the team I was working with at Paris Observatory, we analyzed the mechanisms happening during flares (what we call magnetic reconnection, in three dimensions). We expected a specific behavior of the Sun’s magnetic field in flaring regions from our numerical simulations. This was later confirmed with observations from the Solar Dynamics Observatory space telescope by one of our colleagues, who is indeed a keen observer!

What is it that you like to do when you aren’t working on research

Away from my desk, I love travelling. As a kid, I had the incredible chance to live in several countries on 3 different continents. So I get itchy feet when I am staying too long in the same place. I am just back from Tanzania, where I was lucky to walk with giraffes and bathe in turquoise waters: that definitely made me forget the Sun for a few days! Fortunately, as a scientist, I get to travel a lot for conferences and collaborations, so I get the best of both worlds. I love doing sport (from snowboarding to a more quiet yoga sessions), music (we have a secret band with some other astrophysicists friends, but I can’t tell you about it as it is secret!) and especially dancing.

 

Solar Storm logo (Credit: Miho Janvier)

Can you please explain the SolarStormVR project in more detail?

SolarStorm VR is a project I started when as I was living in Scotland. It started with me meeting a talented moviemaker and talking about doing a project together. I was interested in bringing storytelling as a way to communicate about the science we do, and we thought of using Virtual Reality to excite the young audience. We obtained some funding and spent countless nights working on the project. I keep a lot of good memories from it although it was quite strenuous! As I moved to Paris for my current position, I had to juggle my new science career with touring in science festivals to present our project, which meant a lot of sleepless nights. But the smiles on our visitors’ faces were totally worth it. The project is still alive throughout the website (www.solarstormvr.com) where anyone can either download the video or watch it on YouTube 360.

 

How important is science outreach to your career?

For me, it is very important for several reasons. First of all, I have a passion for what I do and I feel lucky to have a job that is more a passion than a work. In that respect, I want to share this passion because I find space awesome!  Many times however I hear that “science is too complicated” or “I was bad in physics/maths”: for some, science seems like an obscure, incomprehensible field that is secretly kept away from the public in an ivory tower. I want to change that. Giving the chance to anyone to understand how science is being done, to make them participate, is allowing anyone to have critical thinking, which is even more important nowadays with unlimited access to real or fake facts on the Internet. And finally, in astrophysics, the majority our funding is public money. It is our duty as researchers to give back to the society that allows us to do the job we do.

Do you have any words of advice for students that would like to follow the scientist’s path

For young students: science literacy you already have, it is a skill you build. It requires hard work but I believe anyone can become a scientist. Don’t give up if it is your dream.For older students starting a scientific career (PhD students), same advice as my younger self: build a support network; don’t hesitate to ask people to mentor you if you feel you need it. You are in for the long run, so better work with people you trust, who can help you through tough times, and who you will be sharing a drink (or many) at conferences! Some of my best friends are in the field, and they make the job even better!

The 2017 solar eclipse and scientific discoveries

The 2017 solar eclipse and scientific discoveries

The next solar eclipse is upon us. On August 21 the moon will pass between the Sun and an observer’s point of view in America and block out daylight, creating an eerie gloom in the sky. The transit of the moon between the Earth and Sun occurs about every 18 months, but for your particular city it can take several hundreds of years before a new eclipse occurs. The figure below shows the paths of all solar eclipses that occurred or will occur during the 2001 to 2020 period. Few eclipses happen around the North or South pole due to the orbital geometry of the heavenly bodies, so proportionally the odds are higher to experience midday darkness if you live at low or mid latitudes. However, since about 71% of the Earth’s surface is covered with water, most of these eclipses occur at places where no one lives and go by unnoticed. Unless you travel to them!

People have long been fascinated by solar eclipses and records in history have been found as early as 2000 B.C. Throughout history researchers and science enthousiasts have travelled the world to watch eclipses, endeavours which were much more difficult in the early days than with nowadays commercial flights. Maybe you are travelling as well to watch this eclipse.

Paths of total and annular solar eclipses during the 2001-2020 period. Credit: Fred Espenak, NASA/GSFC Emeritus

By studying the sun and the eclipses, scientists can look at features of the solar atmosphere that are otherwise hard to observe from the ground due to the intense brightness of the Sun. Discoveries made during eclipses include observations of the outer parts of the solar atmosphere (solar corona), flames of fire from the sun (prominences, jets), radiation other than visible light (infrared, UV) and otherwise invisible comets travelling around the Sun. During the 1868 eclipse a yellow spectral line was discovered by J. Lockyer in the solar chromosphere from a yet unknown chemical element that turned out to be one of the most abundant chemical species in our universe. He named it after the Greek word for the sun (helios) and it took until 1895 before helium was discovered on Earth.

Even today, scientific knowledge is being advanced by studying the solar eclipse and the effects on our nearby space environment and Earth’s atmosphere. When the moon eclipses the Sun, the illumination over a localised region will change rapidly and Earth’s atmosphere will react to this decrease in solar energy. One such reaction that occurs is in the ionosphere, the higher most reaches of the atmosphere. Solar ultraviolet radiation creates a dynamic layer of charged particles that reflect telecommunication transmissions at very low frequencies around the world. Understanding how this layer reacts to changes in solar radiation can enhance our understanding of the ionosphere and hopefully improve the region’s dynamics in model simulations. The direct blocking of radiation will also have a profound effect on the total amount of radiation that is received by the surface as well on the amount that is reflected back to space by the oceans, clouds and atmosphere. Changes in this radiation budget can in a unique way be investigated during the solar eclipse. Studying these variations, in for example temperature or radiation, during an eclipse are useful to test our current understanding of the Sun’s effect on the atmosphere.

Not only academics, but also citizens can contribute to advances in solar-terrestrial science. The Megamovie project aims to create an open-source archive of nearly 1.5 hours continuous solar eclipse. With this dataset new features in the solar corona on long and short time scales will hopefully be discovered.

So, what will you do on 21 August 2017? Watching the eclipse from your hometown, travelling to the path of totality from across the world or take part in any scientific contribution as citizen or researcher? Hopefully you will enjoy the magical moment and experience something new!

For more information: 

http://www.mreclipse.com/Totality2/TotalityApH.html

https://eclipse2017.nasa.gov/science-ground

https://eclipse.gsfc.nasa.gov/solar.html

Capturing a Whole Total Eclipse of the Sun: Megamovie

Capturing a Whole Total Eclipse of the Sun: Megamovie

by Hugh S Hudson (U. of Glasgow and UC Berkeley)

Normally solar eclipses give an observer only a fleeting moment (minutes at most) to enjoy the solar corona. We aim to amplify that considerably in the August 21 eclipse across North America. The plan is simple: Megamovie will capture everybody’s images, especially those from a group of 1,000 photographc volunteers, and compile them into an open-source archive that (weather permitting) will span an hour and a half of the corona’s life. One can find this program at the URL “eclipsemega.movie“, and in the  smartphone app “Eclipse Megamovie Mobile“.

The path of totality crosses the entire continent of North America, well-populated with eager observers equipped with the latest things in consumer electronics – marvelous cameras plus GPS and the Internet. The previous occurrence, in 1918, had none of that.  The program is thus a citizen-science project, embracing all levels of experience and capability among the observers, and at the same time it will produce a systematic record that we believe will be the first of its kind, and certainly can be the largest. We intend to follow up with citizen-science analysis projects, along the lines of SETI@Home and Zooniverse, to make sense of the very complicated records.

Megamovie does new and original things that will create real science. For the corona, the existence of the archive itself is unique.  Here we will have vast oversampling in the time domain, with access to disturbance modes on short time scales seldom observed with such resolution. Here we expect to see waves and flows in the low corona, by following the intensity variations of discrete features. Of course the Megamovie archive can extend to time scales of tens of minutes, where we know that large-scale structures will show perceptible and dynamically interesting motions. How much does a streamer wobble, and in what mode?

A CME and other structures captured in eclipse observations by Hanaoka et al. (2013); the left panel is an edge-enhanced view of one stacked image at 12-Nov-2012 20:39 UT. The right panel is a difference against observations from a different site at 21:14 (this is a cropped version of Figure 1 of the manuscript used by permission from Dr Y. Hanaoka)

The uniqueness of the August 21 eclipse continues with the coincidental presence of the bright star Regulus. This reference point will show up in all of the deep coronal images. In addition we have recently achieved precise astrometric information about the Moon, derived from the Kaguya and Lunar Reconaissance Orbiter missions; this eclipse will be the first major opportunity to apply this new information to eclipse data and the Sun.

The star field at the time of the August 21, 2017 eclipse,showing the position of the Sun as it moves during totality, and also the nearby bright star Regulus. (Figure provided by H. Hudson)

These advantages should make it possible to analyze and correct many images at a precision  rivaling that of the famous Eddington observations in 1919. We note that this historically important confirmation of general relativity has been repeated with modern detectors such as those found in everyday consumer electronics now. The Megamovie Mobile app (free) provides many resources for smartphone users; the mere timing of Baily’s Beads will make a systematic recording of the shadow path and thereby the local instantaneous radius of the Sun. The app does this automatically, and even without a cheap telephoto attachment, a smartphone camera can get wonderful timing information with precise GPS metadata.

Welcome

Welcome to the ST division blog!

The Solar-Terrestrial (ST) Division of European Geosciences Union (EGU) is starting its own blog! The blog is an initiative by a group of enthusiasts who met during the EGU’s General Assembly in April 2017. We are thrilled to set up this blog that will keep our readers informed about a range of topics relevant to the science of the division.

A CME from the Sun heading towards the Earth. Thanks to the magnetic field enveloping the Earth, we stay protected from the wrath of the Sun.
Credit: Adapted from NASA/Steele Hill

The influence of the Sun on the Earth and our planetary system have shaped a dynamic, constantly evolving scientific area. The Earth’s atmosphere, ionosphere and magnetosphere are strongly moulded by the Sun, solar wind and galactic cosmic rays. We have an armada of spacecrafts and detectors on the ground to record solar eruptive events and their in-situ manifestations. This helps us study the ST sciences.

The Sun fosters life on Earth and acts as the vitalizer of our very existence. However, it spews large amounts of plasma and energy towards the Earth that can hinder day-to-day life in modern society.

Space weather and terrestrial weather are continually influenced by small changes in solar output, which not only varies from day to day but also through longer timescales throughout its lifetime. Studying the Sun and its effects on the near-Earth environment can facilitate more accurate predictions of space and terrestrial weather. Such forecasting can in turn help keep life on this planet safe by having early warning systems.

Research in the ST sciences is very stimulating for us and we wish to share our enthusiasm with our readers. Bringing science to the public is the intent of this blog. Students as well as early career scientists (ECS) will greatly benefit from the broad nature of topics that will be discussed here. Getting everyone excited about science in general and ST studies in particular is our aim. We will discuss papers in the “spotlight” to look at the recent breakthroughs in this field. There will be articles and interviews of featured scientists to discuss post-doc life, career path or alternative careers.

As well as  exciting scientific topics we will also provide informative general highlights and timely deadlines for conferences. From time-to-time our own EGU-ST ECS representative (Jone Reistad) will discuss ECS related opportunities and problems. All in all, this will be a voice for scientists to reach out to the community.

We have planned an extensive series of blogs from our team of experts and other scientists (especially ECSs and students). We encourage guest bloggers to contact the editor. Come back every month for a new and informative blog post.

 

This text was prepared by Kamalam Vanninathan and Athanasios Papaioannou