In the early 1900s the general view of stars was that they contained about the same ratio of elements as Earth. That is, they were made largely of things like iron, silicon, oxygen and the like, and not much in the way of hydrogen and helium. That’s in direct contradiction with what we know today, but it was a reasonable assumption at the time.
A Darker Edge
When you look at an image of the Sun, you might notice that it’s edge appears slightly dimmer than its center. This is an effect known as limb darkening, and its actually quite useful to astronomers.
Hot Water
Yesterday I talked about how water can form on the Moon. It might seem a bit surprising that water exists on the Moon, but it doesn’t sound like a crazy idea. What does sound crazy is the idea that there is water on the Sun’s surface, and yet we know that there is.
Wake Up Sunshine
We generally think of the Sun as a constant in our lives. It rises and sets regularly, and seems to be an unchanging sphere of brilliant light. In fact the Sun has a turbulent surface with prominences that fly off its surface, granules caused by convection in its upper layers, and even the appearance of slightly cooler regions known as sunspots.
Aurora Glow
This week there’s been plenty of solar activity, including a couple of x-class solar flares. Since these flares were aimed in Earth’s general direction there has been some murmuring about “the big one” but these aren’t remotely large in historical terms. They are, however, strong enough that millions could have a rare chance of viewing an aurora.
Doppelganger
Recently in Astrophysical Journal Letters a paper was published on the oldest “solar twin” yet discovered. The star, HIP 102152, is about 250 light years away from us, and about 4 billion years older than our Sun.
Common Core
Our Sun (like other stars) is powered by nuclear reactions within its core. Part of the way we know this is through the observation of solar neutrinos. When solar neutrinos were first observed, the levels observed were less than predicted by about a factor of three, which came to be known as the solar neutrino problem. Since then we’ve come to understand that neutrinos have mass, and can change between flavors (electron, muon, and tauon), which solves the solar neutrino problem. Our neutrino detectors are good enough that we can now produce neutrino images of the Sun, such as the image above, and the rates of neutrino emission are in good agreement with solar core models.
Oh God, Oh God, We’re All Gonna Die
Recently there’s been a flurry of articles about an increase in solar activity, including rumors that Edward Snowden had revealed the NSA knows of a solar flare “killshot” set to cause a global famine that will kill millions. The rumor has since been traced back to a satirical website, but that didn’t prevent the story from being repeated across the internet. The story has flared up again in the past few days on new that NASA has reported the Sun has emitted a coronal mass ejection (CME) in the direction of Earth.
You Could Have Died!
Growing up I was a bit of a risk taker. Along with a few of my friends, I occasionally did things that (while very cool) were in retrospect notoriously dangerous. Occasionally my Mom found out about these activities, which worried her to no end. As she put it, “You could have died!” This is absolutely true. Some of the stunts we pulled could have ended in serious injury or death. It is also true that my friends and I survived childhood largely unscathed. The reason I bring this up is because recently there has been a flurry of stories about solar activity in 2012, and the headlines are much the same “You could have died!”