General articles and links about astronomy and the night sky.
The tiny planet Mercury lingers in the western sky after sunset, still tangled in the lacework of star clusters in the constellation Taurus. The planet reaches greatest eastern elongation on May 7, 2015 at an angular distance of 21º from the Sun. Mercury is visible over the next few days about 10 degrees above the NW horizon for northern-hemisphere observers, and just 5 degrees above the horizon for southern-hemisphere observers. Here’s what to look for in the next few days…
Now to a superb think piece by Lee Billings about a recent search for advanced alien civilizations in other galaxies. While it may sound far-fetched, the search was grounded in hard science. Assuming advanced civilizations have learned to harness the energy of stars to build solar-system-wide habitats, we should be able to see the waste energy in the form of infrared (IR) light over and above the background light of a galaxy. After searching 100,000 galaxies for excess IR, no sign was found beyond what’s expected from natural processes. So maybe there are no advanced civilizations, at least yet. Or perhaps there’s a subtler answer… that advanced life, assuming it exists, might evolve to be efficient and integrated with its natural environment. It’s a fascinating read.<
It’s galaxy season! Between the constellations Leo and Virgo, in a patch of sky no larger than your outstretched hand, you can see dozens of the more than two thousand galaxies of the Virgo cluster, the largest major galaxy cluster to our Milky Way. Have a look at this superb image of part of the Virgo cluster taken with a backyard telescope, and learn a little about how galaxy clusters evolve….
The last few years have seen an explosion of nightscape photography, a combination of landscape and astrophotography using new DSLR cameras with the latest large, low-noise sensors. It’s not an easy form of photography, least of all because you need to stand in complete darkness, in the middle of nowhere, for hours at a time. But I love this art form. One of my very favorite nightscapes is by David Kingham, who from Death Valley, California, managed to image a remarkable “sailing stone” in a dried mud flat with the stars of Orion and Canis Major in the background. It’s a superb piece of photography.
>Finally this week, just to show that sometimes I get to do a little stargazing myself, I present a short observing report from my ‘observer’s log’ taken during a night of backyard galaxy hopping.
Wishing you clear skies,
Thursday, April 30, 2015
The usually reliable Eta Aquarid meteor shower peaks on the night of May 5-6 this year. The shower runs from April 21 – May 20, 2015, with many meteors still visible for several days on either side of the peak. It’s perhaps the best meteor shower of the year for southern hemisphere stargazers, and it’s pretty good for northerners too. The meteors are sandgrain-sized bits left over from Halley’s comet. Like most such showers, the best viewing is just before dawn.
Astronomers at the University of Arizona announced one of the ‘standard candles’ of the universe, exploding stars called Type Ia supernovae, may not be so standard after all. They found more distant Type Ia supernovae might be intrinsically fainter than more nearby events, suggesting the accelerating expansion of the universe is not as pronounced as once thought. This may mean the effect of the mysterious ‘dark energy’ that causes the expansion is also less important. But that doesn’t disprove the existence of dark energy. As Ethan Siegel explains, there are two more independent observations that show something like dark energy (whatever it may be) still accounts for the majority of the universe.
Yesterday, NASA released rather stirring images from the New Horizon’s spacecraft of Pluto and its Texas-sized moon Charon revolving about their common center of mass. The images also show Pluto rotating about its axis, and large-scale surface features on the former planet’s surface. These are the best images yet captured. The view will only get better as New Horizons gets closer to its brief but historic rendezvous with Pluto just 11 weeks from now.
Well, this makes me feel old, but NASA marked the 25th anniversary of the launch of the Hubble Space Telescope last week. The redoubtable instrument, which began its career with a malformed primary mirror, has revolutionized professional astronomy and helped astronomers to generate more knowledge and understanding of the universe in the past 25 years than in the previous 200 years. Hubble helped refine our understanding of the age of the universe, detect atmospheres on exoplanets, and find millions of galaxies in parts of the sky where no galaxies had been seen before. The New York Times has a brief retrospective video on the launch and legacy of Hubble. And Phil Plait published his favorite “12 1/2” images from Hubble in his column at Slate.
Ottawa-based stargazer Andrew Symes continues to refine his imaging techniques using an iPhone and an 8″ Celestron NexStarSE telescope. An iPhone! The small sensor and pixel sizes of smartphone cameras make them unlikely candidates for astrophotography. But clever developers have created apps that enhance the low-light operation of the iPhone camera. So with a little practice and standard post-processing techniques, Symes has shown it’s possible to take quite acceptable images of Jupiter, Saturn, the Moon, and even brighter deep-sky sights directly at the eyepiece of a telescope with an iPhone.
Wishing you clear skies,
Publisher, Cosmic Pursuits