New USPS Stamps Shed Light On NASA Sun Science In Time For Summer
Later this month, the U.S. Postal Service will begin issuing a new series of stamps featuring dramatic images of the Sun from NASA’s Solar Dynamics Observatory.
From its position in a geosynchronous Earth orbit, the Solar Dynamics Observatory (SDO) has studied the Sun’s atmosphere and magnetic field since early 2010. The spacecraft’s mission is to help us understand how the Sun’s magnetic field, and its constant emissions of radiation and charged particles, impact life and technology here on Earth (and in orbit).
“Sunspots, coronal holes, and coronal loops, for example, can reveal how these magnetic fields dance throught he Sun and its atmosphere,” wrote USPS in a statement announcing the new stamp series. “Observing plasma blasts and solar flares can help us better understand and mitigate the impact of such eruptions on technology in space.”
The series features 10 colorized versions of SDO images of the Sun at its most dramatic, designed by Antonia Alcalá. SDO views the Sun in the ultraviolet wavelengths, which we can’t see (but can definitely feel the effects of), so NASA assigned false colors to the images. They’ll be available on June 18. Here’s what to look out for:
In some spots on the Sun’s surface, the Sun’s powerful magnetic field actually slows down the process of convection that keeps hot material churning toward the surface from the depths of the star. These relatively cool spots look dark against the brightness of the Sun’s corona, or outer layer, and it’s easy to think of them as dead spots on an otherwise active star – but they’re actually places of very intense magnetic activity, and they give rise to phenomena like coronal loops, solar flares, and plasma blasts. Sunspots move and change constantly, usually over a period of several days to a few months.
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Arcs of glowing hot ionized gas, called plasma, stretch thousands of kilometers into space from the Sun’s surface. At the base of the arc, you’ll probably find sunspots lurking. The plasma is trapped on the curving lines of the Sun’s magnetic field, so when you look at a coronal loop, you’re watching trapped plasma light up part of the Sun’s magnetic field like a giant stellar neon sign in space. These plasma arcs may collapse in a few seconds, or they may hold their shape for several days before the magnetic field shifts and the giant loop of plasma collapses back into the surface of the Sun.
These intense bursts of solar radiation cover the whole electromagnetic spectrum, from radio waves to gamma rays. When they’re strong enough, solar flares can sometimes briefly disrupt communications and even power grids here on Earth. Solar flares are produced by activity in the Sun’s magnetic field, and they usually erupt from areas near groups of sunspots.
Also called coronal mass ejections, these eruptions of hot gas and plasma usually happen along with solar flares.
In areas where the Sun’s corona is cooler than average (but still very, very hot), the plasma is less dense, and these patches of the Sun’s surface appear darker. The Sun’s surface constantly emits charged particles and radiation into space – scientists call this the solar wind – but solar wind gusts out of these dark regions at twice the average speed, because it’s easier for particles to escape from the Sun’s lower layers through the relatively thin plasma of the coronal holes.