NASA To Launch The Finest Mirrors Ever Made

This Wednesday NASA will launch its High Resolution Coronal Imager (HI-C) mission from White Sands Missile Range in New Mexico, sending a sounding rocket above the atmosphere with some of the best mirrors ever made to capture incredibly-detailed ultraviolet images of our Sun.

HI-C will use a state-of-the-art imaging system to focus on a region near the center of the Sun about 135,000 miles (271,000 km) across. During its brief flight — only ten minutes long — HI-C will return some of the most detailed images of the Sun’s corona ever acquired, with a resolution five times that of previous telescopes… including NASA’s Solar Dynamics Observatory.

While SDO collects images in ten wavelengths, however, HI-C will focus on just one: 193 Angstroms, a wavelength of ultraviolet radiation that best reveals the structures of the Sun’s corona present in temperatures of 1.5 million kelvin. And although HI-C’s mirrors aren’t any larger than SDO’s — about 9.5 inches in diameter — they are “some of the finest ever made.” In addition, an interior “maze” between mirrors effectively increases HI-C’s focal length.

Researchers expect HI-C’s super-smooth mirrors to resolve coronal structures as small as 100 miles (160 km) across (0.1 arcsec/pixel).

“Other instruments in space can’t resolve things that small, but they do suggest – after detailed computer analysis of the amount of light in any given pixel – that structures in the sun’s atmosphere are about 100 miles across,” said Jonathan Cirtain, project scientist for HI-C at NASA’s Marshall Space Flight Center. “And we also have theories about the shapes of structures in the atmosphere, or corona, that expect that size. HI-C will be the first chance we have to see them.”

One of the main goals of HI-C will be to place significant new constraints on theories of coronal heating and structuring, by observing the small-scale processes that exist everywhere in hot magnetized coronal plasma and establishing whether or not there are additional structures below what can currently be seen.

“This instrument could push the limits on theories of coronal heating, answering questions such as why the temperature of the sun’s corona is millions of degrees higher than that of the surface,” said Marshall’s Dr. Jonathan Cirtain, heliophysicist and principle investigator on the mission.

Read more on the NASA news release here.

Top image: A Black Brant sounding rocket containing NASA’s HI-C mission will launch on July 11, 2012 to observe the sun’s corona. (NASA) Bottom image: TRACE image of the Sun at a resolution of 0.5 arcsec/pixel. HI-C will have a resolution 5 times finer.

How Big Was Monday’s CME?


April 16's M-class solar flare erupted with a CME that could dwarf the Earth, shown here to scale. (NASA/SDO/J. Major)

This big! The M1.7-class flare that erupted from active region 1461 on Monday, April 16 let loose an enormous coronal mass ejection many, many times the size of Earth, making this particular writer very happy that our planet was safely tucked out of aim at the time… and 93 million miles away.

The image above was obtained by NASA’s Solar Dynamics Observatory’s AIA 304 imaging instrument on Monday during the height of the event. I rotated the disk of the Sun 90 degrees to get a landscape look over the eastern limb, cropped it down and then added an Earth image to scale — just to show how fantastically huge our home star really is.

(Read “Watch it Rain on the Sun”)

Some minor editing was done to increase contrast and heighten detail in the eruption.

The CME was not directed our way, but it was aimed at NASA’s STEREO-B spacecraft, which will encounter the ejected material full-on.

Read more about this event in a previous Universe Today post here, and check out hi-def videos of the CME from SDO here.

Image credit: NASA/SDO and the AIA science team. Edited by Jason Major.

Huge Coronal Hole Is Sending Solar Wind Our Way

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An enormous triangular hole in the Sun’s corona was captured earlier today by NASA’s Solar Dynamics Observatory, seen above from the AIA 211 imaging assembly. This gap in the Sun’s atmosphere is allowing more charged solar particles to stream out into the Solar System… and toward Earth as well.

Normally, loops of magnetic energy keep much of the Sun’s outward flow of gas contained. Coronal holes are regions — sometimes very large regions, such as the one witnessed today — where the magnetic fields don’t loop back onto the Sun but instead stream outwards, creating channels for solar material to escape.

The material constantly flowing outward is called the solar wind, which typically “blows” at around 250 miles (400 km) per second. When a coronal hole is present, though, the wind speed can double to nearly 500 miles (800 km) per second.

Increased geomagnetic activity and even geomagnetic storms may occur once the gustier solar wind reaches Earth, possibly within two to three days.

The holes appear dark in SDO images because they are cooler than the rest of the corona, which is extremely hot — around 1,000,000 C (1,800,000 F)!

Here’s another image, this one in another AIA channel (193):

AIA 193 image of the March 13 coronal hole

Keep up with the Sun’s latest activity and see more images on NASA’s SDO site here.

Images courtesy NASA, SDO and the AIA science team.

SDO Provides Constant, Unprecedented Views of Sun’s Inner Corona

Cosmic Radiation

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Usually the only time we can see the innermost part of the Sun’s corona is when there is a total eclipse. But now, with the Atmospheric Imaging Assembly (AIA) instrument on NASA’s Solar Dynamics Observatory and a new image processing program, scientists are getting unprecedented views of the innermost corona 24 hours a day, 7 days a week.

“The AIA solar images, with better-than-HD quality views, show magnetic structures and dynamics that we’ve never seen before on the Sun,” said astronomer Steven Cranmer from the Harvard-Smithsonian Center for Astrophysics (CfA). “This is a whole new area of study that’s just beginning.”

The Sun’s outer layer, or corona is composed of light, gaseous matter, and has two parts. The outer corona is white, with streamers extending out millions of miles from the edge of the sun. The inner corona, lying next to the red chromosphere, is a band of pale yellow.

This zoomed-in image shows how the Sun's magnetic field shapes hot coronal plasma. Photos like this highlight the ever-changing connections between gas captured by the Sun's magnetic field and gas escaping into interplanetary space. Credit: NASA/LMSAL/SAO

This outer layer of the Sun’s atmosphere is, paradoxically, hotter than the Sun’s surface, but so tenuous that its light is overwhelmed by the much brighter solar disk. The corona becomes visible only when the Sun is blocked, which happens for just a few minutes during an eclipse.

Now, with AIA, “we can follow the corona all the way down to the Sun’s surface,” said Leon Golub of the CfA.

Previously, solar astronomers could observe the corona by physically blocking the solar disk with a coronagraph, much like holding your hand in front of your face while driving into the setting Sun. However, a coronagraph also blocks the area immediately surrounding the Sun, leaving only the outer corona visible.

The AIA instrument on SDO allows astronomers to study the corona all the way down to the Sun’s surface.
Cranmer and CfA colleague Alec Engell developed a computer program for processing the AIA images above the Sun’s edge. These processed images imitate the blocking-out of the Sun that occurs during a total solar eclipse, revealing the highly dynamic nature of the inner corona. They will be used to study the initial eruption phase of coronal mass ejections (CMEs) as they leave the Sun and to test theories of solar wind acceleration based on magnetic reconnection.

The resulting images highlight the ever-changing connections between gas captured by the Sun’s magnetic field and gas escaping into interplanetary space.

This time-lapse movie shows two days of solar activity observed by the AIA instrument. Both the solar surface and dynamic inner corona are clearly visible in X-rays. Hot solar plasma streams outward in vast loops larger than Earth before plunging back onto the Sun’s surface. Some of the loops expand and stretch bigger and bigger until they break, belching plasma outward.

SDO launched in February 2010.

This video provides more information about the AIA instrument:

SoHO Celebrates its 12th Birthday

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On December 2nd, 1995 a large joint ESA and NASA mission was launched to gain an insight to the dynamics of the Sun and its relationship with the space between the planets. 12 years on, the Solar and Heliospheric Observatory (SoHO) continues to witness some of the largest explosions ever seen in the solar system, observes beautiful magnetic coronal arcs reach out into space and tracks comets as they fall to a fiery death. In the line of duty, SoHO even suffered a near-fatal shutdown (in 1998). As far as astronomy goes, this is a tough assignment.

By the end of 1996, SoHO had arrived at the First Lagrange Point between the Earth and the Sun (a gravitationally stable position balanced by the masses of the Sun and Earth, about 1.5 million km away) and orbits this silent outpost to this day. It began to transmit data at “solar minimum”, a period of time at the beginning of the Solar Cycle, where sunspots are few and solar activity is low, and continues toward the upcoming solar minimum after the exciting firworks of the last “solar maximum”. This gives physicists another chance to observe the majority of a Solar Cycle with a single observatory (the previous long-lasting mission was the Japanese Yohkoh satellite from 1991-2001).

On board this ambitious observatory, 11 instruments constantly gaze at the Sun, observing everything from solar oscillations (“Sun Quakes�), coronal loops, flares, CMEs and the solar wind; just about everything the Sun does. SoHO has become an indispensable mission for helping us to understand how the Sun influences the environment around our planet and how this generates the potentially dangerous “Space Weather�.

The SoHO mission site confidently states that SoHO will remain in operation far into the next Solar Cycle. I hope this is the case as the new Hinode and STEREO probes will be good company for this historic mission.

Source: NASA News Release