10,000th NEAR-EARTH OBJECT DISCOVERED: 10,000 near-Earth asteroids and comets have now been discovered. The 10,000th object, asteroid 2013 MZ5, was detected on June 18th by the Pan-STARRS-1 telescope in Maui. Sobering estimate: NASA says there may be 10 times this number yet to find. [full story]
CORONAL HOLE: The biggest thing on the sun today is not a sunspot, it's a coronal hole. The yawning dark gap in the sun's atmosphere is almost directly facing Earth, as shown in this June 25th image from NASA's Solar Dynamics Observatory:
Coronal holes are places where the sun's magnetic field opens up and allows solar wind to escape. A stream of solar wind flowing from this particular coronal hole will reach Earth on June 29-30. Because the coronal hole is straddling the sun's equator, the solar wind it is sending our way should make a direct hit on our planet's magnetic field. The impact could spark geomagnetic storms around the poles. High-latitude sky watchers should be alert for auroras at the end of the month. Aurora alerts: text, voice.