Hubble captures Planetary Nebula NGC 6751
Planetary nebulae do look simple, round, and planet-like in small telescopes. But images from the orbiting Hubble Space Telescope have become well known for showing these fluorescent gas shrouds of dying Sun-like stars to possess a staggering variety of detailed symmetries and shapes. This composite color Hubble image of NGC 6751 is a beautiful example of a classic planetary nebula with complex features and was selected to commemorate the tenth anniversary of Hubble in orbit. The colors were chosen to represent the relative temperature of the gas - blue, orange, and red indicating the hottest to coolest gas. Winds and radiation from the intensely hot central star (140,000 degrees Celsius) have apparently created the nebula’s streamer-like features. The nebula’s actual diameter is approximately 0.8 light-years or about 600 times the size of our solar system. NGC 6751 is 6,500 light-years distant in the constellation Aquila.
North American Beaver - July evening, Central Michigan
The beaver is not your typical rodent. It’s the largest one on the continent, and the only one that can cut down mature trees. Beavers use the timber to build large, elaborate nests—dome-shaped lodges with underwater entrances—inside ponds. If there is no pond, beavers will create one by building a dam to block a stream. The resulting moat around their lodges keeps wolves, coyotes and other predators at bay.
As semiaquatic rodents, beavers have closeable ears and nostrils, webbed hind feet and very dense fur coats. Their paddlelike tails appear to be covered in scales like a fish, but they aren’t. Rather, the skin is grooved in a scaly pattern, which makes the thick tail more flexible.
Beavers can drastically alter landscapes. Working in family groups of four to eight, a beaver colony can cut down more than a ton of trees per year. This colony has dammed a stream with logs, mud and stones to make a pond. The land is so newly flooded that some trees have not yet drowned.
By altering streams, beavers expand wetlands , offering rich habitat for other species. Beaver ponds can also control runoff and reduce erosion. Eventually, this pond will clog with sediment. At that point, or when all accessible trees are cut, the colony will abandon its effort and begin again elsewhere.