A while back I wrote about the cycles of our Sun, so let’s spend a bit more time on two major aspects of the Sun – sunspots and solar flares.
A sunspot is a cooler part of the Sun’s surface. With average surface temps of 10,000 F, the 6,700 F sunspots seem dark by comparison. They form when bends in the magnetic field lines dip into the sun, deflecting the rising hot plasma to the side. Similar to placing a small pot of water into a large boiling pot, displacing the rising hot water.
Solar flares also follow magnetic field lines that arc above the Sun. These rising bands of plasma can be many tens of times larger than the Earth. If the field lines snap, a blast of plasma is sent out into space, called a Coronal Mass Ejection (CME). This is the stuff that can cause blackouts and auroras on Earth.
As the sun continues into its active cycle, look for more images like this of our closest star.
Every year, as the Earth orbits around the Sun, our planet passes through the ancient paths of icy comets and rocky asteroids. Those objects have shed gasses and bits of rock which linger in space.When Earth runs into this trail of space debris, the atmosphere acts as a shield. If the collision between rock and air is fast enough, you get what we call a “shooting star” or meteor. It’s not a star at all; often it’s a rock the size of a grain of sand! The friction caused by the air causes it to glow and vaporize into a streak of light.
Although random space rocks can cause meteors anytime, these predictable intersections with old objects creates “meteor showers” with many shooting stars per hour. Dates are roughly the same each year, but the number of meteors can vary widely from year to year.
The next shower is tonight! The Eta Aquarids at about 50 faint meteors possible per hour. To observe, just find a clear sky and blankly look up. Your eyes will pick up on meteors all on their own.
Did you know there is a remote-control helicopter on Mars! It recently took images of the Red Planet’s surface showing the aerodynamic backshell protecting it and the rover Perseverance on its entry into the Martian atmosphere.
It’s almost routine now to see images from the Mars rovers of the desert like landscapes they are exploring to better understand the geology, chemistry, and possible biology of a planet that once had oceans and rivers like Earth. This most recent rover Perseverance had a stowaway craft, Ingenuity, a small solar-powered, semi-autonomous twin rotor helicopter that has made a total of 26 short flights to date. Amazing!
But a by-product of robotic exploration of other planets is the litter and trash that is left behind in the landing process. To actually see this piece of tech and large parachute that slowed the rover to a safe landing speed is unreal, let alone a view from the skies of Mars.
The world is losing its night skies. An unintended consequence of the wonder of electric light is the loss of natural light from distant stars. Modern lighting has allowed us to work and live beyond the window of sunrise and sunset, and without the safety issues of candlelight. This new light can also bounce upward, where the glow of the Milky Way becomes harder to see.
To raise awareness about light pollution, International Dark Sky Week is April 22-30, 2022. It’s a good time to learn how you can help your area have darker skies, and perhaps save a few dollars on power bills.
In big cities, some kids have never seen a truly dark sky. During the Northridge earthquake in LA, it’s said, when the city went dark after the electricity grid failed altogether, people asked if the glow in the sky caused the earthquake. They were seeing the Milky Way for the first time!
I would say parts of Sierra County would qualify for official dark sky status, likely those shielded from the glare of Sacramento, Reno, Grass Valley, and now Truckee I suppose. More at the official website: https://idsw.darksky.org/
While the Sun appears as a round glowing sphere in the sky, its glare masks lots of activity. The Sun, like all stars, is a ball of super-hot gases undergoing nuclear fusion. Hydrogen in a star’s core is subjected to intense heat and pressure resulting in the formation of helium and other heavier elements, including our own Sierra County gold from some other long ago star’s fusion.
In addition, the sun is rotating on its own axis every 27 days or so which is quite fast considering you could fit 1.3 million Earths inside. This rotation at the Sun’s equator is faster than at its poles, due to its composition of plasma (super-hot gas). The sun’s magnetic field is bent and warped by this difference in speeds.
Every 11 years or so, the sun’s magnetic field flips, resulting in increased solar activity like sunspots and solar flares. We are now entering a new period of solar activity, so look for more images from astrophotographers of the sun soon.