![]() The data for this new mosaic image was collected as NASA's sun-touching spacecraft, the Parker Solar Probe, made its 12th close pass of the star, racing through the outer limits of its corona and coming closer to the sun than any other craft ever had done before. This could eventually allow solar physicists to see the frequency of nanoflares, how they release energy, and thus whether they are responsible for coronal heating. Individual nanoflares are too faint to spot amongst the sun's light output, but NuSTAR can spot radiation from high-temperature material created by a lot of nanoflares happening in the same location at the same time. Regular flares don't happen frequently enough to heat the corona, but nanoflares may happen more regularly, perhaps often enough to cause this excess heating. These are smaller than regular solar flares but like their larger cousins, also produce material hotter than the average temperature of the corona. The source of this unexpected heating may be nanoflares, small bursts of heat, and light in the sun's atmosphere. NASA says that because heat from the sun passes out from its core, this is as surprising as the air around a fire being 100 times hotter than the flames of the fire itself. These speeds are so high that the particles can escape the Sun's gravity.Ĭonceptual animation (not to scale) showing the Sun's corona and solar wind.Common theories of star composition suggest that deeper layers should be hotter, and this is true everywhere throughout the sun except when passing from the upper atmosphere, the corona, which can reach temperatures of up to 3.6 million degrees Fahrenheit ( 2 million degrees Celsius), to the photosphere below, which, at about 6,200 degrees F (3,700 degrees C) is up to 500 times colder. ![]() The corona's temperature causes its particles to move at very high speeds. From it comes the solar wind that travels through our solar system. ![]() We can view these features in detail with special telescopes. These include streamers, loops, and plumes. The Sun's magnetic fields affect charged particles in the corona to form beautiful features. This is the force that makes magnets stick to metal, like the door of your refrigerator. The surface of the Sun is covered in magnetic fields. But astronomers think that this is only one of many ways in which the corona is heated. In the corona, the heat bombs explode and release their energy as heat. The mission discovered packets of very hot material called "heat bombs" that travel from the Sun into the corona. Yet the corona is hundreds of times hotter than the Sun’s surface.Ī NASA mission called IRIS may have provided one possible answer. The corona is in the outer layer of the Sun’s atmosphere-far from its surface. This is the opposite of what seems to happen on the Sun.Īstronomers have been trying to solve this mystery for a long time. But when you walk away from the fire, you feel cooler. Imagine that you’re sitting next to a campfire. The solar corona, and the coronae of solar-type stars, consist of a low-density magnetized plasma at temperatures exceeding 106 K. ![]() The corona’s high temperatures are a bit of a mystery. NASA researchers successfully launched a sophisticated X-ray solar imager on a brief but potentially illuminating suborbital flight via sounding rocket to gather new insight regarding how and why the Sun’s corona grows so much hotter than the actual surface of Earth’s parent star. Image of corona from NASA's Solar Dynamics Observatory showing features created by magnetic fields. This low density makes the corona much less bright than the surface of the Sun. Why? The corona is about 10 million times less dense than the Sun’s surface. The corona reaches extremely high temperatures. Find tips on how to safely view an eclipse here. Remember to never look directly at the Sun, even during an eclipse. ![]()
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