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Last Post 20 Mar 2018 12:30 PM by  KD Leka
storms
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Brenda M
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19 Mar 2018 07:29 AM
    Hello,

    If there are no sunspots right now, why have there been huge auroras? I thought auroras were only seen if there was sunspot activity?

    thank you
    >50 Answers
    Posts:69 >50 Answers

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    19 Mar 2018 09:02 AM
    There have been rather large coronal holes on the Sun lately, as seen on this website:
    https://solarmonitor.org/. Look at the middle image of the second row. This image is identified as "AIA 193Å 20180319 14:31". The 193 is the wavelength (in Angstroms), the 20180319 is today's date, the time 14:31 is Universal Time. The dark area in that image is a coronal hole, coronal holes are the source of high-speed solar wind, charged particles like electrons, protons, ions. At the moment, that coronal hole is pointed at us; therefore, the charged particles, when they arrive at Earth, can trigger a space-weather storm, which can result in aurorae.
    >300 Answers
    Posts:376 >300 Answers

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    19 Mar 2018 10:17 AM
    Hello! The interaction between the Sun and Earth's magnetosphere is very complicated, and there are many different things that can produce aurora. Under normal, everyday conditions, the solar wind can make aurora at high latitudes - places like Alaska, Canada, Scandinavia in the northern hemisphere, and at Antarctica in the southern hemisphere. The typical high-latitude aurora are usually related to something scientists call a substorm, where the solar wind makes changes in the Earth's magnetic field on the night side of our planet that send energetic particles and electrical currents into the ionosphere. Right now, there has been a small geomagnetic storm occurring due to the coronal holes that Mitzi mentioned. Geomagnetic storms often produce aurora at even lower latitudes than what is normally observed, so that people in Michigan or Minnesota might be able to see aurora. The processes that make aurora during geomagnetic storms driven by higher than normal speed solar wind from a coronal hole are similar to what happens during a typical substorm, but due to stronger driving by the solar wind, the substorms can be much stronger and last longer than normal. Geomagnetic storms typically have many different periods of substorm activity. In fact, the term "substorm" was created many years ago when scientists believed that having a lot of substorms was what created a geomagnetic storm. We now know that geomagnetic storms result from a build-up of a giant current system around the Earth in space called the ring current in response to high-speed solar wind from coronal holes or the impact of a coronal mass ejection (CME) shock wave. However, the term substorm is still used to describe the processes that make the auroral activity.
    >100 Answers
    Posts:101 >100 Answers

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    20 Mar 2018 12:30 PM
    Another good website (with awesome pictures!): spaceweather.com
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