High up in the clear blue noontime sky, the sun appears to be much the same day-in, day-out, year after year.
But astronomers have long known that this is not true. The sun does change. Properly-filtered telescopes reveal a fiery disk often speckled with dark sunspots. Sunspots are strongly magnetized, and they crackle with solar flaresmagnetic explosions that illuminate Earth with flashes of X-rays and extreme ultraviolet radiation. The sun is a seething mass of activity.
Until its not. Every 11 years or so, sunspots fade away, bringing a period of relative calm.
This is called solar minimum, says Dean Pesnell of NASA's Goddard Space Flight Center in Greenbelt, MD. And its a regular part of the sunspot cycle.
The sun is heading toward solar minimum now. Sunspot counts were relatively high in 2014, and now they are sliding toward a low point expected in 2019-2020.
While intense activity such as sunspots and solar flares subside during solar minimum, that doesnt mean the sun becomes dull. Solar activity simply changes form.
For instance, says Pesnell, during solar minimum we can see the development of long-lived coronal holes.
Coronal holes are vast regions in the suns atmosphere where the suns magnetic field opens up and allows streams of solar particles to escape the sun as the fast solar wind.
Pesnell says We see these holes throughout the solar cycle, but during solar minimum, they can last for a long time - six months or more. Streams of solar wind flowing from coronal holes can cause space weather effects near Earth when they hit Earths magnetic field. These effects can include temporary disturbances of the Earths magnetosphere, called geomagnetic storms, auroras, and disruptions to communications and navigation systems.
During solar minimum, the effects of Earths upper atmosphere on satellites in low Earth orbit changes too.
Normally Earths upper atmosphere is heated and puffed up by ultraviolet radiation from the sun. Satellites in low Earth orbit experience friction as they skim through the outskirts of our atmosphere. This friction creates drag, causing satellites to lose speed over time and eventually fall back to Earth. Drag is a good thing, for space junk; natural and man-made particles floating in orbit around Earth. Drag helps keep low Earth orbit clear of debris.
But during solar minimum, this natural heating mechanism subsides. Earths upper atmosphere cools and, to some degree, can collapse. Without a normal amount of drag, space junk tends to hang around.
There are unique space weather effects that get stronger during solar minimum. For example, the number of galactic cosmic rays that reach Earths upper atmosphere increases during solar minimum. Galactic cosmic rays are high energy particles accelerated toward the solar system by distant supernova explosions and other violent events in the galaxy.
Pesnell says that During solar minimum, the suns magnetic field weakens and provides less shielding from these cosmic rays. This can pose an increased threat to astronauts traveling through space.
Solar minimum brings about many changes to our sun, but less solar activity doesnt make the sun and our space environment any less interesting.
For more news about the changes ahead, stay tuned to science.nasa.gov
Originally posted here:
Solar Minimum is Coming | Science Mission Directorate
- 2D Laser Profiling Scanner for Detecting Targets - November 8th, 2009 [November 8th, 2009]
- NASA Energy Concept Could Harness the Power of Ocean Waves - November 8th, 2009 [November 8th, 2009]
- Data Acquisition Modules - November 8th, 2009 [November 8th, 2009]
- Dr. Scott Barthelmy, Research Scientist, Laboratory for High Energy Astrophysics, Goddard Space Flight Center, Greenbelt, MD - November 8th, 2009 [November 8th, 2009]
- Laser Tracker Ensures Accurate Alignment of Ares I Components - November 8th, 2009 [November 8th, 2009]
- Dual Cryogenic Capacitive Density Sensor - November 8th, 2009 [November 8th, 2009]
- Advanced Technologies Will Help Hubble Yield More Remarkable Discoveries - November 8th, 2009 [November 8th, 2009]
- Dr. Gerard Holzmann, Senior Research Scientist at the Laboratory for Reliable Software, NASA’s Jet Propulsion Laboratory - November 8th, 2009 [November 8th, 2009]
- NASA Research Will Help Aircraft Avoid Ocean Storms and Turbulence - November 8th, 2009 [November 8th, 2009]
- NASA Awards 2008 Software of the Year - November 8th, 2009 [November 8th, 2009]
- Here Come The Tricorders - Update - November 8th, 2009 [November 8th, 2009]
- China's View on Space - November 8th, 2009 [November 8th, 2009]
- Milsat Coordination and Tracking Issues - November 8th, 2009 [November 8th, 2009]
- Trash Talking and End Runs at NASA HQ - November 8th, 2009 [November 8th, 2009]
- Ares 1-Y is Toast - November 8th, 2009 [November 8th, 2009]
- Beyond Augustine - November 8th, 2009 [November 8th, 2009]
- Analyzing LCROSS' Plume - November 8th, 2009 [November 8th, 2009]
- Live Event: NASA-Sponsored Power Beaming Challenge - November 8th, 2009 [November 8th, 2009]
- JSC Wants To Build a Replicator - November 8th, 2009 [November 8th, 2009]
- USA: Looking For Ways To Hang On - November 8th, 2009 [November 8th, 2009]
- Lunar Lander Challenge Prizes Awarded - November 8th, 2009 [November 8th, 2009]
- Senate Votes To Restore NASA Budget Cuts - November 8th, 2009 [November 8th, 2009]
- New FAA Regs for Commercial Reentry - November 8th, 2009 [November 8th, 2009]
- TEDxNASA: An Invitation-Only NASA Meeting - Unless You Are Lucky - November 8th, 2009 [November 8th, 2009]
- Close Call For Courtney Stadd - November 8th, 2009 [November 8th, 2009]
- Space: A Waste? - November 8th, 2009 [November 8th, 2009]
- Making NASA Cool - November 8th, 2009 [November 8th, 2009]
- Engaging JSC’s Next Gen: A Leadership Analysis - November 8th, 2009 [November 8th, 2009]
- Dumpster Diving for Rockets - November 8th, 2009 [November 8th, 2009]
- TEDx NASA - November 8th, 2009 [November 8th, 2009]
- Reflections On a Business Trip in Huntsville - November 8th, 2009 [November 8th, 2009]
- Staying the Course - November 8th, 2009 [November 8th, 2009]
- The Economics of Space - November 8th, 2009 [November 8th, 2009]
- Ideas at Work - November 8th, 2009 [November 8th, 2009]
- Blah Blah Blah - Why We Should Care About Social Media - November 8th, 2009 [November 8th, 2009]
- Will White House Speak Soon About NASA? - December 12th, 2009 [December 12th, 2009]
- Software Aids Design of Ares V Composite Shroud Structure - December 13th, 2009 [December 13th, 2009]
- ASDX Series of silicon pressure sensors - December 13th, 2009 [December 13th, 2009]
- Industry Update: Analysis & Simulation Software - December 13th, 2009 [December 13th, 2009]
- Battery Will Provide Backup Power for Space Shuttles - December 13th, 2009 [December 13th, 2009]
- NASA Employee Claims To Have Witnessed Hijacking Planning - December 13th, 2009 [December 13th, 2009]
- Big Party in The Mojave Tonight - December 13th, 2009 [December 13th, 2009]
- Looking at Boulders on the Moon - December 13th, 2009 [December 13th, 2009]
- SpaceBook Featured by White House - December 13th, 2009 [December 13th, 2009]
- New Ways to Use Constellation Stuff - December 13th, 2009 [December 13th, 2009]
- LaRC internal Poll Update - December 13th, 2009 [December 13th, 2009]
- Coalition for Space Exploration Does a (Much Needed) Reboot - December 13th, 2009 [December 13th, 2009]
- Lunar Orbiter: Comparing Old and New Images - December 13th, 2009 [December 13th, 2009]
- Boulder Trails On The Moon - December 13th, 2009 [December 13th, 2009]
- Vote for John Grunsfeld - National Geographic Adventurer of the YeAR - December 13th, 2009 [December 13th, 2009]
- Charlie Bolden at WIA/AIAA - December 13th, 2009 [December 13th, 2009]
- Live Webcast From The Lunar Orbiter Image Recovery Project - December 13th, 2009 [December 13th, 2009]
- Big Aerospace Warns of Job Cut Impact - December 13th, 2009 [December 13th, 2009]
- The Boulders of Copernicus - December 13th, 2009 [December 13th, 2009]
- shame on us - December 13th, 2009 [December 13th, 2009]
- 2009 Space Elevator Games - December 13th, 2009 [December 13th, 2009]
- Random Hacks of Kindness - December 13th, 2009 [December 13th, 2009]
- TEDx NASA Tickets Available to the Public - December 13th, 2009 [December 13th, 2009]
- It’s better in person - December 13th, 2009 [December 13th, 2009]
- Leading Amidst the Disruptive Innovation Storm - December 13th, 2009 [December 13th, 2009]
- Space: What’s NOT to Hope for? - December 13th, 2009 [December 13th, 2009]
- Government in the Digital Age - December 13th, 2009 [December 13th, 2009]
- SpaceUp – A Space Unconference - December 13th, 2009 [December 13th, 2009]
- Starfleet Academy? - December 13th, 2009 [December 13th, 2009]
- Crowdsourcing NASA - December 13th, 2009 [December 13th, 2009]
- Bringing Home The Bacon - December 14th, 2009 [December 14th, 2009]
- Anti-Space Mom with Pro-Space Kids - December 14th, 2009 [December 14th, 2009]
- How Quickly We Forget - December 14th, 2009 [December 14th, 2009]
- WISE Launch A Success - December 14th, 2009 [December 14th, 2009]
- Dynetics Buys Orion Propulsion - December 15th, 2009 [December 15th, 2009]
- New NASA Governance Structure Under Development - December 16th, 2009 [December 16th, 2009]
- Bolden Meets With Obama on Wednesday - December 16th, 2009 [December 16th, 2009]
- MSFC Procurement Doesn't Understand what "Open Source" Means - December 16th, 2009 [December 16th, 2009]
- Bolden Meets With Obama - December 17th, 2009 [December 17th, 2009]
- Parker Griffith AT MSFC Today - December 18th, 2009 [December 18th, 2009]
- Why Your NASA Computer May Not Work Properly - December 18th, 2009 [December 18th, 2009]
- Lakes and Fog on Titan - December 18th, 2009 [December 18th, 2009]
- Waterworld Found - December 18th, 2009 [December 18th, 2009]
- Pandora Could Exist - December 18th, 2009 [December 18th, 2009]
- Laurie Leshin Is The New ESMD Deputy AA - December 18th, 2009 [December 18th, 2009]