A Burst of Solar Energy

All five of our solar system’s bright planets are visible in our nighttime skies during May, although not all at the same time, and not all of them for the entire month.

The main attraction is Venus, which has been dominating the evening sky for the past couple of months and will continue to do so for another couple of months. Throughout May it shines brilliantly in the west and sets up to two hours after the end of dusk.

The red planet, Mars, is also visible throughout the evening hours, although it continues to fade as it falls farther and farther behind Earth in their respective orbits around the sun. Saturn, meanwhile, rises during the mid-morning hours and is up in our southeastern sky by the beginning of dawn.

Jupiter, after passing on the far side of the sun from Earth last month, begins emerging into the dawn sky during May. On the morning of Wednesday, May 17, the thin crescent moon is very close to Jupiter, and occults—or passes directly over—the giant planet shortly before sunrise. During the latter days of May, Mercury also makes an appearance in our morning sky, although it remains low in twilight.

The number of sunspots—relatively cool regions of the sun’s surface (although still very hot by our standards)—waxes and wanes over an approximate 11-year cycle. We are now approaching another sunspot maximum, which should take place within the next one to two years. During such times, active events such as solar flares and coronal mass ejections—eruptions of electrically charged particles off the sun’s surface—are more frequent and stronger than at other times along the cycle.

When these charged particles interact with Earth’s atmosphere, they excite the various gases and cause them to shine, in much the same manner as the gases in a neon sign. We call this an aurora. This is what causes the northern lights in the northern hemisphere, with a similar phenomenon occurring in the southern hemisphere.

As the number of sunspots increase the number and strength of aurora displays increase. These generally occur at higher latitudes—like a very strong display that many parts of the northern U.S. and northern Europe witnessed back in mid-March. However, on rare occasions they can be seen from closer to the equator, including from New Mexico.