Last month we saw some auroras here in Nederland. Faint as they were, it was nice to see them at all, this far south. News outlets mentioned solar activity that caused the auroras, but some of the accounts were a little confusing. This month, I’ll explain everything you need to really know about the effects of solar storms on our earth.

The sun has storms? Yes, indeed. And space has weather? Yup. Both of which are monitored by the U.S. government in Boulder. Here’s how it all works.

Two things worth knowing about the sun are: First, it’s not solid. It’s mostly sort of squishy. Second, it has super-strong magnetic fields.

As a liquid body, the sun’s equator spins faster than its poles. This causes its magnetic field to distort like this: >. The two ends on the left are the sun’s poles, which lag behind the >’s tip on the right, where the equator is. This unequal race twists and stretches the sun’s magnetic field lines like knotted rubber bands. Where the magnetic field’s stretching and twisting is most severe, it makes cooler zones that we see as dark sunspots.

When the twisted rubber-band field lines finally snap, they release colossal explosions called solar flares. With an energy of up to ten billion million tons (ten billion megatons) of TNT (as compared to the largest-ever H-bomb yield of 60 megatons), solar flares make a lot of X-rays, light, and radio waves, which reach earth in eight minutes. (The sun’s distance of 93 million miles means we always see it time-delayed by eight minutes.) Those initial speed-of-light signals, picked up by US government satellites and ground stations, are collected at NOAA’s Space Weather Prediction Center (SWPC, pronounced swipsee) in Boulder. They’re the warning flags for what happens next.

Which is, a big burst of protons and electrons, moving at close to the speed of light, are on their way. Moving a bit slower than the speed of light, they take about half an hour to get here, if they’ve been slung in our direction. Arriving, they get caught in our planet’s magnetic field, called the geomagnetic field. Being charged, they spiral around the geomagnetic field lines. They bounce back and forth between the north and south poles. Eventually, they collide with oxygen and nitrogen in the upper atmosphere and convert their energy into light, which we see as auroras in the polar zones.

Sometimes the best (or worst, depending on your perspective) is yet to come: a coronal mass ejection aimed at earth. A CME is a few billion tons of particles that gets burped out of the sun’s surface following a flare. Carrying its own magnetic field, a CME storm can reach earth in anything from hours to a few days. But when a CME storm arrives, look out. The massive CME slams into, and squeezes, the geomagnetic field like a tennis ball in your fist. The resulting geomagnetic storm (as monitored at a station north of Boulder) generates electrical currents in the earth. Those currents can knock out entire power grids.

Solar flares and CMEs disrupt radio systems, including GPS, and can damage satellites. Astronauts can be injured, and homing pigeons can lose their way. (Many pigeon fanciers are on NOAA’s spaceweather alert list.) On the upside, magnificent auroras may be seen in southern locales like Colorado.

Space storm effects can, disconcertingly, be mistaken for radar jamming and other precursors to nuclear attack. Which is why NOAA’s space weather alerts go out worldwide, to help ensure that nobody mistakes a magnetic storm for a nuclear attack. Learn more at swpc.noaa.gov, and join their space-weather alert list if you like.

In June Skies:

The sun begins the month in Taurus, entering Gemini on the summer solstice, June 21 when days and nights will be 15 and 9 hours long, respectively.

The moon’s dates are: New June 6; First Quarter June 14; Full (Strawberry Moon) June 21; Last Quarter June 28.

June Meteor Showers: The Arietids (parent, either asteroid 1566 Icarus or comet 96P/Machholz) and Bootids (ba-OO-tids) (parent, comet 7P/Pons-Winnecke) peak on June 10 and 27 respectively. The Arietids are visible in Nederland just before sunrise; the Bootids are good just after dusk.

Best Sky Viewing Nights (Minimal Moon): June 1-13 and after June 28.

Sunset (Mid-Month): Leo with Regulus is prominent at WSW; the Gemini Twins Castor and Pollux are below and to the right. Arc from the Big Dipper’s arm to red Arcturus, then on to bright-white Spica in the south.

Midnight (Mid-Month): Vega, Deneb and Altair form the Navigator’s Triangle, spanning the northeast to nearly overhead.

Sunrise (Mid-Month): The Great Square of Pegasus is just eastward of being overhead. The Pleiades rise just ahead of the sun, while Hercules is low in the west.

Mercury is lost in the sun.

Venus is lost in the sun.

Mars is low in the east before sunrise.

Jupiter is barely visible in the east just before sunrise.

Saturn is low in the southeast at dawn.

Notable Space Missions: Boeing’s Starliner space capsule scrubbed its first possible takeoff date on June 1 and rescheduled for Wednesday, June 5, with June 6 as an alternate. This will be the last test flight before Starliner enters operational service in 2025.

Frank Sanders, a spectrum scientist at the U.S. Department of Commerce in Boulder, takes astronomy-related inquiries at backyardastronomy1@gmail.com.