A comet suddenly appeared out of nowhere
and is now P/2010 H2 (Vales): prediscovery observations, the actual discovery, also reported here and here as well as by the discoverer and images and reports of April 21, April 20, April 19, April 18 (more, more) and April 17 (more, mehr). • A fragment has apparently broken off comet C/2009 K5 as images from April 24 show; on April 25 the comet was inbetween a galaxy and a star cluster (description, b/w version; animation by different observers).
• Details about the current outburst of comet SW1, also an April 5 picture. • P/2010 A2 on April 17 with a star cluster and April 7. • Siding Spring on April 22, April 17 and April 12. • Comet Wild on April 16 and April 10 (from this observatory in Namibia). • A new Comet C/2010 G2 (Hill). • Studies of Churyumov-Gerasimenko's coma (also the German original). • And Ulysses data show that McNaught had the longest tail ever, plasma-wise (another and another press release and a story).
Planetary action, continued - with many Saturn moon shadow transits
Neptune is currently close to where it was discovered; next year it will have completed one orbit. • Saturn on April 24 (more, more) and April 23 (more, more), with various moon shadows in transit (compare that to these and these 2009 reports), and April 12. • Mars on April 20. • The Moon/Venus/Mercury evening show in a composite and invidually on April 17 from Germany (more, more), April 16 from the U.S. (more), Italy (more, more), the U.K. (more, with Venus close-up, more), the Isle of Wight, Germany (more) and India (more in the stream) and April 15 from the U.S., from the U.K. and Germany (more).
An observation of the Moon exactly at new
was successful on April 14 - but an elongation record as claimed it was not: Already in in 2008 the Moon was imaged at the same distance from the Sun! • Two solar prominences on April 25, a CME movie of April 13 (stills, a still), sunspots on April 6 and Proba 2 observations of April 3. Plus science news on a CME tracked from Sun to Earth all the way, ACE & STEREO in space weather forecasts and yet another Sun/Earth climate claim, also reported here, here, here and hier. And how the Earth's orbital changes affect its climate.
• A possible nova in Sco (pics), a nova in Sgr, more analysis (ctd.) of the Eps Aur pics and the Nature paper as a preprint, plus a cataclysmic variable in the Kepler field. • The ISS in transit over the H-Alpha Sun, a lot of hi-res ISS and Discovery images here (also a Discovery flare), here (explained here), here (analysis), here and here - plus the view down at night!
No significant atmospheric optical effects due to the Iceland volcano
The eruption of Eyjafjallajökull (the pronounciation is given here at the end!) had mostly subtle effects on sky colors and visibility as already outlined here a week ago as well as by seasoned sky observers here and here. Sometimes observations were attributed without evidence to the volcano's ash, and it remains to be seen whether the sky near the Moon has something to tell. Hard data on the state of the atmosphere over Europe have been collected a lot with more sophisticated means and are summarized e.g. hier, here, here or here.
There is a detailled report (earlier English version) about the 1st DLR research flight of April 19 (mehr, mehr, mehr, mehr, früher, mehr), and there was a 2nd flight (outcome and conclusions). Also reports about another, another and yet another research flight and groundbased work in Stuttgart, Hamburg and Hohenheim plus from the Helmholtz Soc. (more).
Some thoughts on the real danger (more), a lot of satellite pics (also from Radarsat 2, Proba 1, ALOS, EO-1 [also from yesterday] and Terra), a dramatic video with shock waves in the plume and another one, pictures of flashes in the plume, general thoughts about volcanism in the solar system, what Earth has in store and what the plane-free skies meant, some pseudoscience and also some humor (more, more). • The variation of NLCs has been modelled. • And particle acceleration over thunder clouds.