Basic astronomy and night sky information
Second only to the rings of Saturn, Jupiter’s Great Red Spot (GRS) is probably the most iconic planetary feature in the solar system. Unlike the rings, which aren’t going away any time soon, recent observations of an apparent unraveling of the GRS suggest big changes in this iconic feature, if not its impending demise [Read more…] about The Disappearing Great Red Spot
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As the world celebrates the 50th anniversary of the still astonishing Apollo 11 moon landing, we backyard stargazers can also get in on the fun (indeed many of us grizzled amateur astronomers can trace our interest in the night sky to the space program of the 1960s). With a modest telescope and good seeing, nearly anyone with a little observing experience can see the region of the Moon where Neil Armstrong and Buzz Aldrin briefly walked, and observe the three tiny craters named for the two famous moonwalkers and their crew mate Michael Collins who remained alone in lunar orbit to pilot the Apollo 11 command module [Read more…] about See the ‘Craters of Apollo 11’
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When sight-seeing larger nebulae (like the North America Nebula) and big star clusters (like the Double Cluster or Beehive), it’s usually best to stick with lower magnification and wider fields of view to take in the entire object. But most deep sky objects benefit from greater magnification, sometimes much greater. To demonstrate this, I prowled around in the constellation of Hercules, using my 8-inch Celestron Edge HD scope and an 8mm eyepiece, giving a magnification of 250x.
The first object on my tour was the planetary nebula NGC 6210. Like many planetaries, it has a high surface brightness that enables it to bear high magnifications well. At low powers it looks like a tiny bluish dot. 250x brings out considerable visual character in this 16 arc second object. Slightly oval, its edges are diffuse. Colorful as many planetaries are, it shows an aqua tint with hints and flashes of a fierce electric blue. I found that an 8-inch scope isn’t quite big enough to show these colors strongly in this particular object, but a 12-inch or larger instrument will make them unmistakable, and then you’re viewing an exotic object indeed. I did not consistently see the nebula’s central star, though this should not be difficult at magnitude 12.7. This may be due to the consistently rough seeing I experience in this valley of the southern Sierra Nevada range, where I’m surrounded by mountains on all sides. This tends to muddle the faint star into the bright glow of the nebula.
[Read more…] about High-Power Hercules
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The summer ‘monsoons’ have obliterated the stars for the past couple of weeks and at least for one week more. But a good stargazer still needs to look up from time to time, which is how I found a formation of mammatus clouds passing overhead after an afternoon and evening of heavy thunderstorms near Calgary, Canada.
These ominous and distinctively shaped clouds are usually formed on the underside of anvil-shaped cumulonimbus clouds that cause severe thunderstorms. These sagging pouches are mostly made of ice crystals. An individual “pouch” can range anywhere from one to three kilometers in diameter, and a mammatus cloud field can stretch for dozens of kilometers across the sky.
Their formation is still poorly understood, but they may form from cold, dense air sinks toward the earth from higher up. This sinking air pokes through the bottom of the anvil resulting in the pouch-like appearance. So they may be a rare occurrence of cloud formation caused by sinking air rather than rising air. The cloud droplets and ice crystals eventually evaporate and the mammatus clouds dissipate. These clouds were passing quickly and moved over the horizon before they faded away.
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Observers in a narrow band across the southern Pacific Ocean and north-central Chile and Argentina enjoyed a rare spectacle today: a total solar eclipse. The lovely seaside towns of La Serena and Coquimbo, Chile, enjoyed two minutes and thirteen seconds of totality, and observers at some of the world’s great astronomical observatories got in on the fun. This is the first total solar eclipse visible anywhere since the ‘Great American Eclipse‘ of August 21, 2017. The next total solar eclipse occurs on December 14, 2020, once again across the South Pacific, Chile, and Argentina.
