Early on June 7, 2011, the Sun once again showed signs of waking up from the last solar minimum: it unleashed a powerful solar flare. The x-ray emission from this flare can be seen in Wolfram|Alpha:
We humans often notice the passage of time by observing our watches; the movement of the Sun, Moon, and stars across the sky; or by the records left by our ancestors in diaries or other historical records—but these are just fleeting moments in the eyes of geological time. We are used to thinking about recorded history. But recorded history is just a blink when compared to the length of time called pre-history. Recorded history only goes back a few thousand years. The Earth is far older.
It’s hard for humans to grasp just how long the Earth has been here. Using a variety of methods, geologists have been able to put together many pieces of a very complicated puzzle. After all, how do you assemble a puzzle when you’re not sure what the finished picture should look like? From studying processes that are happening today, such as geological composition, rates of deposition, weathering, climatology, biology, and Earth’s magnetic field, geologists can extend these processes back to ancient times and learn what the Earth was like billions of years ago. When combined with data points such as those found in the fossil record, these extrapolations can be constrained, and the picture starts to emerge from the puzzle. More »
As you go about your day, especially during the hot summer season, you probably don’t think much about the Sun other than that it makes you want to go for a quick dip in the swimming pool to cool off. After all, the Sun rises and sets every day (for those of us outside the Arctic and Antarctic Circles), and people just take it for granted without much thought.
The Sun is far more dynamic than you might think, although thankfully we don’t usually feel direct effects of its activity from Earth’s surface. The atmosphere and magnetic field of the Earth provide a nice buffer zone that protects us.
Every 11 years, the Sun completes a cycle that is fairly regular. During solar maximum, the number of sunspots is higher than usual, and during solar minimum (which we are just coming out of), it is relatively spot free.
The Sun is still coming out of solar minimum, but activity is slowly returning. At about 8:55 UTC on August 1, a measurable solar flare triggered an event known as a coronal mass ejection (CME). This is where the “atmosphere” of the Sun sends out a burst of energized plasma. In this case, nearly the entire Earth-facing side of the Sun was involved, so effects on the Earth are more likely. Here’s the X-ray signature of the solar flare that triggered the CME:
Wolfram|Alpha’s coverage of the universe continues to grow. We have now added a large collection of observed supernovae in the universe to our ever-expanding compendium of astronomical knowledge.
What exactly is a supernova? It’s a catastrophic event in the life of a star.
The full details are very complex, but basically supernovae are the visible signs of the deaths of stars more massive than the Sun. As with all other stars, massive stars spend most of their lives fusing hydrogen gas into helium in their cores. This results in a buildup of “ash” (end product of fusion reactions) in the core that eventually chokes off the hydrogen fuel from the hottest area of the core. With no new fuel, there is less energy being produced to counter the gravity trying to squeeze the star’s huge mass more tightly together. The result is that the star’s core begins to collapse as gravity overtakes the outward pressure. This results in heating the core—eventually enough that the ash can begin fusing into heavier molecules, initially carbon and oxygen. The cycle repeats, each time beginning and ending with different products and creating the next fuel source. Eventually, the core contains iron. Iron cannot liberate energy from fusion, so at this point, energy generation in the core suddenly stops, and the full mass of the star comes crashing down and a shock wave rips the star apart. This explosion is called a Type II supernova and results in the formation of a neutron star (or more rarely a black hole). More »
Sitting in your office watching and cursing the rainy outdoors, have you ever wondered what the weather beyond our protective atmosphere is like?
Yes, there is weather even in the empty space above Earth’s atmosphere. Space weather typically refers to phenomena resulting from solar activity. It’s also one of the latest content additions to Wolfram|Alpha. Space weather includes things like sunspots, solar X-rays, and solar wind, as well as their effects on the Earth itself (e.g. aurorae, radio communication blackouts, and in extreme cases power outages).
The Sun has an 11-year cycle. Every 11 years, the number of sunspots rises to a peak and then falls to a minimum. Sunspots result from areas of strong magnetic fields on the Sun that cool the surrounding gas and makes the gas appear darker. When these tangled magnetic fields reconnect, the plasma carried along with it can be flung with huge amounts of energy away from the Sun. If it is directed toward Earth, we may observe a number of effects. Depending on how the magnetic field is oriented, it may bounce off the Earth’s magnetic field with no effect. If oriented the other way, the plasma funnels down the Earth’s magnetic field lines until it encounters the atmosphere, causing it to glow. This glowing is known as the aurora borealis in the northern hemisphere and the aurora australis in the southern hemisphere.
The sunspot cycle likely plays a role in Earth’s global climate. The exact nature of its effect is still a hot area of active research. More sunspots mean more energy is likely to be absorbed by the Earth from the Sun. Fewer sunspots mean less energy and potentially a cooler climate. Between 1645 and 1715, sunspots on the Sun nearly vanished. During the same period, called the Maunder minimum, Europe experienced colder-than-average temperatures, contributing to what some have called “the little ice age”. Data for sunspots goes back much further than most other space weather data. Most other phenomena could not be measured until the advent of artificial satellites, and many much more recently than that.
In 1859, the first and most powerful solar flare ever observed occurred, known as the Carrington event. Within a couple of days of the flare, the Earth’s magnetic field oscillated wildly from the magnetized plasma thrown toward us. The magnetic field lines of the Earth bounced back and forth across telegraph wires, causing massive failures and even melted wires from the induced currents. An event of that strength today would cause untold havoc, as we are far more dependent on telecommunications via both satellites and land-based wires. More »