A stronger than anticipated impact from material flung from the sun by a large flare in sunspot group 1429 made for lively auroras last night from the northern U.S. and Canada. They never reached high in the sky, but from a location with a good horizon to the north, the many rays that briefly flared around 12:30-1 a.m. were a pleasant surprise.
Guess what? We may be in for more with minor auroral storms predicted for higher latitudes (Minnesota maybe?) this evening as a result of the same coronal mass ejection that sparked last night’s display combined with the effects of a large coronal hole that directly faced Earth earlier this week. These “holes” in the sun atmosphere or corona are very interesting phenomena. Normally the tightly looped magnetic fields around sunspot groups constrain the constant wind of particles that blows from the sun called the solar wind. The loops form the same way iron filings arrange themselves around a magnet here on Earth. On the sun, hot gases trace the magnetism that surrounds sunspot groups.
Coronal holes are places on the sun where the magnetic fields stream directly into space unconstrained. They carry ferry away particles into space at speeds around 1.8 million miles per hour – the reason the wind from holes is called the fast solar wind. Because the particles are moving at high speed, they can sometimes make their way past Earth protective magnetic field and spark displays of northern lights high in our atmosphere. Let’s hope we’re so fortunate tonight.
Earlier this month NASA released a new, more detailed image from the Lunar Reconnaissance Orbiter of the Apollo 11 moon landing site taken from only 15 miles high. That’s about twice the cruising altitude of a transcontinental air flight. The details revealed are marvelous and include an experiment to measure moonquakes (PSEP) and the retro reflectors that are still used to this day to precisely measure the distance to the moon via lasers shot at the reflectors and received back on Earth.
My favorite are the footpaths in the lunar soil made by astronauts Neil Armstrong and Buzz Aldrin. The mottled gray ground around the module shows they spent most of their time “close to home”, while a single track made by Armstrong leads to the rim of Little West crater 164 feet (50 meters) away.
Thanks in part to discoveries made by on-the-ground investigation and rock collecting by the Apollo astronauts and closeup photos taken by the LRO, we know a lot more about how the moon evolved. Take a look at the short video below. It provides our best explanation to date – without words – of why the moon looks the way it does today.