It's a once in a lifetime event: the June 5th Transit of Venus across the sun. Watch the world wide webcast sponsored by the Coca-Cola Science Center and NASA. | | | ISS TRANSIT OF VENUS: High above Earth, astronaut Don Pettit is about to become the first human to witness and photograph a transit of Venus from space. His images and commentary will be streamed to Earth during the crossing. [full story] [video] VENUS PASSES MERCURY, APPROACHES THE SUN: Venus is approaching the sun in advance of the June 5th Transit of Venus. From here on Earth, the second planet has become difficult to see wrapped in bright sunlight. The Solar and Heliospheric Observatory, however, has no such trouble. SOHO's onboard coronagrah blocks the glare to reveal planets otherwise invisible: A 24-hour movie shows that Mercury is exiting stage left as Venus plunges deeper into sunlight. Updated images may be found here. Amateur astronomers who manage to locate Venus in broad daylight will find that the planet has turned into a delightfully slender crescent. This is happening because Venus is turning its nightside to Earth, with only a sliver of reflected sunlight still shining over the planet's limb. The crescent could soon become a ring. When Venus is less than few degrees away from the sun, the horns of the crescent sometimes reach around and touch, producing a complete annulus. The effect is caused by particles in upper layers of Venus's atmosphere which scatter sunlight around the circumference of the planet. The ring is very difficult to observe, and often only black-belt astrophotographers are able to record the phenomenon. Keep an eye on SpaceWeather's realtime photo gallery to see how Venus shape-shifts in the days ahead: Space Weather Real Time Image Gallery [Submit your photos] [NASA videos: 2012 Transit of Venus, ISS Transit of Venus] CORONAL HOLE: Spewing solar wind, a yawning dark fissure in the sun's atmosphere is turning toward Earth. NASA's Solar Dynamics Observatory photographed the "coronal hole" during the early hours of June 1st: Coronal holes are places where the sun's magnetic field opens up and allows the solar wind to escape. A stream of solar wind flowing from this coronal hole will reach Earth on June 5th - 7th, possibly stirring geomagnetic storms. High-latitude sky watchers should be alert for auroras. Aurora alerts: text, voice. Potentially Hazardous Asteroids ( PHAs) are space rocks larger than approximately 100m that can come closer to Earth than 0.05 AU. None of the known PHAs is on a collision course with our planet, although astronomers are finding new ones all the time. On June 2, 2012 there were 1293 potentially hazardous asteroids. Notes: LD means "Lunar Distance." 1 LD = 384,401 km, the distance between Earth and the Moon. 1 LD also equals 0.00256 AU. MAG is the visual magnitude of the asteroid on the date of closest approach. | The official U.S. government space weather bureau | | The first place to look for information about sundogs, pillars, rainbows and related phenomena. | | Researchers call it a "Hubble for the sun." SDO is the most advanced solar observatory ever. | | 3D views of the sun from NASA's Solar and Terrestrial Relations Observatory | | Realtime and archival images of the Sun from SOHO. | | from the NOAA Space Environment Center | | the underlying science of space weather | |