Past Forecasts
Thor's Helmet
Thor not only has his own day (Thursday), but a helmet in the heavens. Popularly called Thor's Helmet, NGC 2359 is a hat-shaped cosmic cloud with wing-like appendages. Heroically sized even for a Norse god, Thor's Helmet is about 30 light-years across. In fact, the cosmic head-covering is more like an interstellar bubble, blown by a fast wind from the bright, massive star near the bubble's center. Known as a Wolf-Rayet star, the central star is an extremely hot giant thought to be in a brief, pre-supernova stage of evolution. NGC 2359 is located about 15,000 light-years away toward the constellation of the Great Overdog. This sharp image is a combination of deep images taken in light emitted by hydrogen (red) and oxygen (blue). The star in the center of Thor's Helmet is expected to explode in a spectacular supernova sometime within the next few thousand years. Sky Surprise: What picture did APOD feature on your birthday? (after 1995)
Credit & Copyright: Josep Drudis, Christian Sasse
A 0–9 score for how stirred up Earth’s magnetic field is, measured every 3 hours by magnetometers around the world. 0–2 is quiet, 3–4 is unsettled, and 5 or more is a geomagnetic storm. The higher it goes, the farther from the poles the northern lights reach. Around Kp 5, people in Washington State can sometimes see them low in the north.
- Kp 5 G1 minor
- Kp 6 G2 moderate
- Kp 7 G3 strong
- Kp 8 G4 severe
- Kp 9 G5 extreme
A rough guide based only on the current Kp: Unlikely below 4, Possible at 4–5, Likely at 6–7, Strong at 8+. It isn’t for your exact location, so use “Your sky this week” for odds where you are. Clouds and city lights matter too.
Learn more at NOAA SWPCA stream of charged particles flowing from the Sun, measured by spacecraft about 1.5 million km (1 million miles) toward the Sun from Earth. It usually blows at 300–500 km/s. Faster than about 600 km/s often means stormier space weather, and whatever is measured now reaches Earth roughly 30–60 minutes later.
Learn more at NOAA SWPC