After days of suspenseful quiet, huge sunspot AR2665 finally erupted on July 14th (0209 UT), producing a powerful and long-lasting M2-class solar flare. Extreme ultraviolet telescopes onboard NASA’s Solar Dynamics Observatory recorded the blast:
The two hour long outburst of X-rays and high energy particles led to lots of ionization in earth’s upper atmosphere:
Shortwave radio blackouts were subsequently observed over the Pacific Ocean and especially around the Arctic Circle. This map from NOAA shows the affected geographic regions.
See these space weather reports from NOAA for more about the effects of the solar flare on earth:
Long before totality (when the Moon is only covering part of the Sun’s face), go to a nearby tree and look in the shade of the tree’s shadow. You will see hundreds of crescent images of the partially covered Sun all over the ground! In fact, this is a safe way to view all the partial phases of the eclipse without harming your eyes. Where do all these many images come from? The gaps between the tree’s leaves act like a pinhole camera by projecting the Sun’s image on the ground.
** 2017 Total Solar Eclipse Science Briefing – video of NASA briefing on eclipse science:
During a June 21 media briefing from the Newseum in Washington, representatives from NASA, other federal agencies, and science organizations discussed the opportunity for scientific study offered by the total solar eclipse that will cross the U.S. on August 21.
** 2017 Total Solar Eclipse Safety Briefing – video of a NASA briefing on watching the eclipse safely
During a June 21 media briefing from the Newseum in Washington, representatives from NASA, other federal agencies, and science organizations provided important information about safely viewing the total solar eclipse that will cross the U.S. on August 21.
For the first time in 47 years, South Carolina will experience a once-in-lifetime total solar eclipse of the Sun! On August 21, 2017, Anderson Jockey Lot will host a viewing of the event as a free public service. Astrophysicist and veteran total solar eclipse observer, Rick Boozer will provide expert running commentary.
Assuming clear skies, the Anderson Jockey Lot will be the best viewing location of the totality climax along the I-85 corridor with longest totality time in this area of 2 minutes and 38 seconds. Totality for the City of Greenville will be 2 minutes and 10 seconds – nearly 30 seconds less. Spartanburg, at most, will only have several seconds.
New images taken with the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile have revealed otherwise invisible details of our Sun, including a new view of the dark, contorted centre of a sunspot that is nearly twice the diameter of the Earth. The images are the first ever made of the Sun with a facility where ESO is a partner. The results are an important expansion of the range of observations that can be used to probe the physics of our nearest star. The ALMA antennas had been carefully designed so they could image the Sun without being damaged by the intense heat of the focused light.
Astronomers have harnessed ALMA‘s capabilities to image the millimetre-wavelength light emitted by the Sun’s chromosphere — the region that lies just above the photosphere, which forms the visible surface of the Sun. The solar campaign team, an international group of astronomers with members from Europe, North America and East Asia , produced the images as a demonstration of ALMA’s ability to study solar activity at longer wavelengths of light than are typically available to solar observatories on Earth.
The ALMA telescope has been used to study the Sun for the first time. It is also the first time that an ESO facility has been used to study our nearest star. This ESOcast Light takes a quick look at the main facts and why this is an important step for the future of solar observing.
Astronomers have studied the Sun and probed its dynamic surface and energetic atmosphere in many ways through the centuries. But, to achieve a fuller understanding, astronomers need to study it across the entire electromagnetic spectrum, including the millimetre and submillimetre portion that ALMA can observe.
Since the Sun is many billions of times brighter than the faint objects ALMA typically observes, the ALMA antennas were specially designed to allow them to image the Sun in exquisite detail using the technique of radio interferometry — and avoid damage from the intense heat of the focussed sunlight . The result of this work is a series of images that demonstrate ALMA’s unique vision and ability to study our Sun.The data from the solar observing campaign are being released this week to the worldwide astronomical community for further study and analysis.
This comparison video starts with a view of the solar disc at ultraviolet wavelengths from the NASA Solar Dynamics Observatory. The final view of the disc comes from recent observations by ALMA at millimetre wavelengths. Credit: NASA-SDO, ALMA (ESO/NAOJ/NRAO)
The team observed an enormous sunspot at wavelengths of 1.25 millimetres and 3 millimetres using two of ALMA’s receiver bands. The images reveal differences in temperature between parts of the Sun’s chromosphere . Understanding the heating and dynamics of the chromosphere are key areas of research that will be addressed in the future using ALMA.
Sunspots are transient features that occur in regions where the Sun’s magnetic field is extremely concentrated and powerful. They are lower in temperature than the surrounding regions, which is why they appear relatively dark.
This video shows a major sunspot on the surface of the Sun. The initial view is in visible light, from NASA’s Solar Dynamics Observatory and the final view is from ALMA, at millimetre wavelengths. Credit: NASA-SDO, ALMA (ESO/NAOJ/NRAO)
The difference in appearance between the two images is due to the different wavelengths of emitted light being observed. Observations at shorter wavelengths are able to probe deeper into the Sun, meaning the 1.25 millimetre images show a layer of the chromosphere that is deeper, and therefore closer to the photosphere, than those made at a wavelength of 3 millimetres.
ALMA is the first facility where ESO is a partner that allows astronomers to study the nearest star, our own Sun. All other existing and past ESO facilities need to be protected from the intense solar radiation to avoid damage. The new ALMA capabilities will expand the ESO community to include solar astronomers.
 The ALMA Solar Campaign team includes: Shin’ichiro Asayama, East Asia ALMA Support Center, Tokyo, Japan; Miroslav Barta, Astronomical Institute of the Czech Academy of Sciences, Ondrejov, Czech Republic; Tim Bastian, National Radio Astronomy Observatory, USA; Roman Brajsa, Hvar Observatory, Faculty of Geodesy, University of Zagreb, Croatia; Bin Chen, New Jersey Institute of Technology, USA; Bart De Pontieu, LMSAL, USA; Gregory Fleishman, New Jersey Institute of Technology, USA; Dale Gary, New Jersey Institute of Technology, USA; Antonio Hales, Joint ALMA Observatory, Chile; Akihiko Hirota, Joint ALMA Observatory, Chile; Hugh Hudson, School of Physics and Astronomy, University of Glasgow, UK; Richard Hills, Cavendish Laboratory, Cambridge, UK; Kazumasa Iwai, National Institute of Information and Communications Technology, Japan; Sujin Kim, Korea Astronomy and Space Science Institute, Daejeon, Republic of Korea; Neil Philips, Joint ALMA Observatory, Chile; Tsuyoshi Sawada, Joint ALMA Observatory, Chile; Masumi Shimojo (interferometry lead), NAOJ, Tokyo, Japan; Giorgio Siringo, Joint ALMA Observatory, Chile; Ivica Skokic, Astronomical Institute of the Czech Academy of Sciences, Ondrejov, Czech Republic; Sven Wedemeyer, Institute of Theoretical Astrophysics, University of Oslo, Norway; Stephen White (single dish lead), AFRL, USA; Pavel Yagoubov, ESO, Garching, Germany and Yihua Yan, NAO, Chinese Academy of Sciences, Beijing, China.
 Indeed, this lesson has been learned the hard way: the Swedish–ESO Submillimetre Telescope (SEST) had a fire in its secondary mirror assembly after the telescope was accidentally pointed at the Sun.
 A map of the whole disc of the Sun was also made with a single ALMA antenna, using a technique called fast-scanning, at a wavelength of 1.25 millimetres. The accuracy and speed of observing with a single ALMA antenna makes it possible to produce a map of the entire solar disc in just a few minutes. These maps show the distribution of temperatures in the chromosphere over the whole disc at low spatial resolution and therefore complement the detailed interferometric images of individual regions of interest.