The Sun unleashes at the Earth. In this image from the NASA Solar and Heliospheric Observatory (SOHO) spacecraft’s LASCO instrument, the Sun is seen emitting a coronal mass ejection directly toward the Earth a few hours ago, producing the delicate “halo”. The Sun itself, represented by the white circle, is hidden behind an “occulting disk" that shields the sensitive LASCO cameras from the blinding intensity of its surface in order that it can record the structure of its (relatively) faint outer atmosphere, the corona. The light from this eruption reaches the Earth almost immediately after the even, but the stream of charged particles launched away from the Sun takes several days to cross the 150 million kilometers between us and our star. If it were more closely aligned with the position of the Earth in its orbit a few days from now, such an event could result in disruption to radio communications and bright aurorae over the Earth’s poles.
Update (2PM CDT, 20 August): Prediction models confirm this CME is, in fact, Earth-directed and will hit us on about Saturday, 24 August.
Web-Based Tools For Tracking Solar Activity
As we head into the peak of solar Cycle 24 this summer, I thought it would be a good idea to list some websites that are useful for keeping an eye on what the Sun is up to.
Why care about this? Solar activity is rapidly ramping up and significantly affects the geophysical environment of our planet. Bursts of high-energy particles emitted from solar flares can damage Earth-orbiting satellites, disrupt terrestrial radio communications, interfere with GPS navigation, and even threaten the integrity of electrical power grids.
Here are a summary of some sites and what they have to offer:
☀ Current Solar Data (convenient, one-page summary of plots from NOAA)
☀ Spaceweather (the go-to website for information about current solar activity and space weather forecast information)
☀ SolarSoft ”Latest Events” (a single page, graphical, ‘at-a-glance’ summary of recent solar imagery and activity levels)
☀ SolarHam (lots of graphical information about solar activity mainly pertinent to terrestrial, long-wave radio propagation; of interest to amateur radio operators and others)
☀ Solar Terrestrial Activity Report (oodles of information about current solar activity levels and events in the geomagnetic environment compiled by Jan Alvestad)
☀ Planetary K-Index (a numerical representation of the current level of solar-geomagnetic activity near the Earth; when K ≥ 7, auroral activity at mid-latitudes is likely)
☀ Helioviewer (an interactive tool for visualizing solar activity data, mostly spacecraft imagery)
☀ POES Auroral Oval (a realtime depiction of the “auroral oval” around the Earth’s poles from orbiting satellites; useful for predicting where aurora may be seen on the ground)
☀ The Watchers Solar Activities Archive (blog consisting of short news-style updates about solar goings-on)
This list is by no means exhaustive, but should serve as a good jumping-off point for those interested in tracking the activity of our dynamic Sun.
(Image credit: NASA/Steele Hill)