Recent Astronomy Articles at Cosmic Pursuits

Is the Universe Too Dangerous for Life?

August 15, 2019 by Brian Ventrudo Filed Under: Science

Artist’s impression of a gamma ray burst hitting the Earth. The gamma rays would trigger changes in the Earth’s atmosphere that might make life as we know it impossible. Credit: NASA

It’s a question that inevitably arises in conversations about the cosmos: does life exist elsewhere in the universe?

For those who hope the answer is “yes”, the harvest of exoplanets by NASA’s Kepler Space Telescope and other telescopes over the past decade has been hugely encouraging. As of mid 2019, in the small slice of sky under its exacting gaze, analysis of Kepler’s measurements found more than two thousand extrasolar planets, and all telescopes have confirmed some 3,700 exoplanets. Extrapolating these results, astronomers estimate our Milky Way galaxy alone might hold some 10 billion planets that may have the temperature and composition to harbor habitable life. With that much real estate, many believe that complex or even intelligent life must have formed on at least some of these? [Read more…] about Is the Universe Too Dangerous for Life?

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The Disappearing Great Red Spot

July 26, 2019 by Joe Bergeron Filed Under: Solar System

Jupiter and the cyclonic feature known as the Great Red Spot, lower right, in 2019. New dissipative activity is shrinking and may be destabilizing this famous feature in Jupiter’s atmosphere. Image credit: Anthony Wesley.

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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See the ‘Craters of Apollo 11’

July 18, 2019 by Brian Ventrudo Filed Under: Solar System

The astronaut Edwin (Buzz) Aldrin at Tranquility Base on July 20, 1969.

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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High-Power Hercules

July 11, 2019 by Joe Bergeron Filed Under: Deep Sky

The globular cluster Messier 13 in the constellation Hercules. The far more distant galaxy NGC6207 is at lower left. Image credit: Roth Ritter.

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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Mammatus Clouds After Thunderstorms

July 7, 2019 by Brian Ventrudo Filed Under: Atmospheric Sightings

Mammatus clouds passing over Calgary, Canada on July 6, 2019.

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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