Welcome to the permanent site of the Solar Wind Sherpas! Throughout this site, you will find information on who we are, the science that we do, total solar eclipses, instruments, publications, previous eclipse expeditions, previous blogs, and of course, all the information on this year’s expedition, including the blog!
Note: Some of the pages are currently under construction, but are coming soon. Make sure to come back and navigate through all the pages!
The Solar Wind Sherpas is an intrepid team of international scientists and explorers who travel the world to observe and collect data on total solar eclipses (TSEs). The team, appropriately named given the massive amount of equipment they bring to each of the (usually remote) observing sites, is led by Dr. Shadia R. Habbal of the Institute for Astronomy in Honolulu, Hawai’i. To date, the Solar Wind Sherpas have carried out 14 eclipse expeditions including India (1995), Syria (1999), Libya (2006), China (2008), the Arctic (2015) and Indonesia (2016).
Starting with a group of six in 1995, the Solar Wind Sherpas have now over two dozen members who share the same passion for exploration and discovery to unveil the secrets that keep the solar corona at over a million degress.
Our team is one of the very few worldwide who has capitalized on the diagnostic potential of multi-wavelength observations of coronal emission lines, leading to a number of discoveries, as demonstrated by our publications list.
What is a Total Solar Eclipse?
A total solar eclipse (TSE) occurs when the Moon passes between the Earth and the Sun covering the solar disk and casting a shadow over Earth. Specifically, the Sun’s diameter, which is 400 times bigger than the Moon’s and 400 times farther from Earth than the Moon, combined with planetary motion, results in the alignment of the Sun, the Moon and the Earth every 12 to 18 months.
Totality occurs when the Sun’s disk is completely covered by the Moon. This occurs because the Moon is at the correct distance from the Earth to appear to be the same size as the Sun’s disk. It is only during totality that we are able to see the Sun’s atmosphere, or corona. The brightness of the solar disk hides the dimmer atmosphere on a regular basis.
Eclipse Sunglasses: Why and When?
Eclipse sunglasses are a safe way to view the Sun at any time other than during totality. In particular, as the Moon starts to cover the Sun (this is called first contact), look through the glasses in order to see the crescent shape forming. For about an hour, as the Moon continues to cover the Sun, the crescent will continue to get smaller and smaller until it disappears and the Sun is completely covered by the Moon (this is called second contact).
At second contact, it is safe to remove the sunglasses as totality has been reached. At this point, when the corona is visible to the naked eye, the structure of the corona, white rays and streamers radiating around the lunar disk can be seen. The intensity of the corona is much like that of a full Moon. Once the Moon begins to uncover the Sun (this is called third contact) and continues to move across the sky, the eclipse can be viewed in reverse order. Once again, eclipse sunglasses must be worn.
Beyond the Beauty Lies the Science
From myths in ancient times to the scientific age, we have come a long way in our understanding of the Sun and the solar corona. Beyond the solar surface, or photosphere, lies an atmosphere that manifests itself naturally only during a total solar eclipse. The Spanish astronomer José Joaquín de Ferrer bestowed the name corona, or crown, to the bright halo that appears during totality. Since then, we have developed our current understanding of this atmosphere, its composition, what defines its ‘shape’ and what fuels its expansion.
Complementing eclipse observations with imaging instruments in an uninterrupted manner over extended periods of time, covering a broad range of wavelengths, from the visible to X-rays, is essential for achieving a comprehensive view of the corona and its expansion into interplanetary space. Eclipse observations were the first to raise fundamental questions pertaining to the solar atmosphere, namely its corona, and its expansion into interplanetary space. These questions can be summarized as follows: 1) what causes the corona to be so hot? 2) where does the solar wind originate from? and 3) what determines the stability or instability of magnetic structures?
“The whole time there was nothing but the Sun and the silence.”
—Albert Camus, The Stranger
The Solar Wind Sherpas are dedicated to studying the solar wind (the gas escaping from the Sun). During total solar eclipses, we look at the corona in white light (light that can be seen with the naked eye) and with special filters, which see only the emission of certain elements that we know are present in the corona. From this, we produce an image that shows, for example, Fe XIV (iron that has been ionized 13 times), or Fe XI (iron that has been ionized 9 times), etc. Each image shows the distribution of these ions in the corona, which translate into the distribution of the temperature. Since the ionized material is controlled by the Sun’s magnetic field, the distribution of temperature is controlled by the magnetic field. However, we can capture the distribution by imaging the emission of the different ions.
Our group’s addiction with observations of total solar eclipses stems from the unique science from such phenomena. Every eclipse observation has yielded new results that enhance our understanding of the solar corona. Not only have we shown the variations in the distribution of temperature, we continue to acquire information about the Sun’s magnetism, a tool through which we can go back to fundamental questions of mechanisms that enable the Sun to produce such a hot corona. See “Observations and Experiments” for more details.
The 2017 Total Solar Eclipse
On 21 August 2017, in a span of 90 minutes, the Moon’s shadow will fall upon Oregon and spread to South Carolina. With a couple of minutes at each step along the way, millions can witness the clockwork of planetary motion that will reveal the beauty of their own star.
The upcoming eclipse will offer unique opportunities for conducting a range of scientific experiments to unravel the secrets of the corona. In order to maximize our chances of obtaining good data, we will be observing from five different sites located between Oregon and Nebraska. Identical equipment will be used at all sites except for spectrometers, which will be used at four out of the five sites.
Each of the primary sites will have the following identical systems: (1) Imaging in Fe XI 7892 ̊A, Fe XIV 5303 ̊A, Ar X 5536 ̊A and Ar XI 6918 ̊A, (2) imaging spectroscopy with triple channel spectrographs, and (3) broad-band white light imaging. The secondary sites will be limited to imaging in Fe XI, Fe XIV, broad-band white light and triple channel spectrographs.
Observing Sites of the Sherpas
Nine Sherpas will be observing from Mitchell, OR. Totality will begin at 18:22 UT (10:22 AM local time) and last for 2 minutes and 3 seconds at their location in Mitchell. Observations will be carried out using white light cameras, multi filter imagers and a 3-channel spectrometer.
Eight Sherpas will be observing from Mackay, ID. Totality will begin at 18:32 UT (11:32 AM local time) and last for 2 minutes and 4 seconds at their location in Mackay. Observations will be carried out using white light cameras, multi filter imagers and a 3-channel spectrometer.
Whiskey Mountain, WY
Three Sherpas will be observing from the top of Whiskey Mountain in Wyoming. Totality will begin at 18:38 UT (11:38 AM local time) and last for 2 minutes and 21 seconds at the top of the mountain. Observations will be carried out using white light cameras and multi filter imagers.
Six Sherpas will be observing from Guernsey, WY. Totality will begin at 18:47 UT (11:47 AM local time) and last for 2 minutes and 16 seconds at their location in Guernsey. Observations will be carried out using white light cameras, multi filter imagers and a 3-channel spectrometer. Naty Alzate will be giving a public lecture before the eclipse. Date and time TBD.
Six Sherpas will be observing from Alliance, NE. Totality will begin at 18:50 UT (11:50 AM local time) and last for 2 minutes and 30 seconds at their location in Alliance. Observations will be carried out using white light cameras, multi filter imagers and a 3-channel spectrometer. Martina Arndt will be giving a public lecture before the eclipse. Date and time TBD.
—2017 eclipse website containing maps, information and merchandise
—A NASA article containing basic detailed information for eclipse day
—An article from Space.com
—An explanation of eclipse terms and stages
—NASA’s eclipse website on past and future eclipses
—NASA’s main website for this year’s eclipse
—A Physics Today article detailing the history and science behind observations of the corona.