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The summer Perseids are here! 

 

The Perseid meteor shower is the best of the year! It peaks on a Moonless summer night from 4 p.m. EST on August 12 until 4 a.m. EST on August 13.

Because the new Moon falls near the peak night, the days before and after the peak will also provide nice, dark skies. Your best window of observation is from a few hours after twilight until dawn, on the days surrounding the peak.

Unlike most meteor showers, which have a short peak of high meteor rates, the Perseids have a very broad peak, as Earth takes more than three weeks to plow through the wide trail of cometary dust from comet Swift-Tuttle.

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The Perseids appear to radiate from the constellation Perseus, visible in the northern sky soon after sunset this time of year. Observers in mid-northern latitudes will have the best views.

You should be able to see some meteors from July 17 to August 24, with the rates increasing during the weeks before August 12 and decreasing after August 13.

Observers should be able to see between 60 and 70 per hour at the peak. Remember, you don’t have to look directly at the constellation to see them. You can look anywhere you want to-even directly overhead.

Meteor showers like the Perseids are caused by streams of meteoroids hitting Earth’s atmosphere. The particles were once part of their parent comet-or, in some cases, from an asteroid.

The parade of planets Venus, Jupiter, Saturn and Mars–and the Milky Way continue to grace the evening sky, keeping you and the mosquitoes company while you hunt for meteors.

Watch the full.  What’s Up for August Video:

There are so many sights to see in the sky. To stay informed, subscribe to our What’s Up video series on Facebook.

(Source: nasa, Via sagansense)

What Happens in the Brain During Sleep?

 

John Peever, director of the Systems Neurobiology Laboratory at the University of Toronto, and Brian J. Murray, director of the sleep laboratory at the Sunnybrook Health Sciences Center, respond:

The function of sleep has mystified scientists for thousands of years, but modern research is providing new clues about what it does for both the mind and body. Sleep serves to reenergize the body’s cells, clear waste from the brain, and support learning and memory. It even plays vital roles in regulating mood, appetite and libido.

Sleeping is an integral part of our life, and as research shows, it is incredibly complex. The brain generates two distinct types of sleep—slow-wave sleep (SWS), known as deep sleep, and rapid eye movement (REM), also called dreaming sleep. Most of the sleeping we do is of the SWS variety, characterized by large, slow brain waves, relaxed muscles and slow, deep breathing, which may help the brain and body to recuperate after a long day.

When we fall asleep, the brain does not merely go offline, as implied by the common phrase “out like a light.” Instead a series of highly orchestrated events puts the brain to sleep in stages. Technically sleep starts in the brain areas that produce SWS. Scientists now have concrete evidence that two groups of cells—the ventrolateral preoptic nucleus in the hypothalamus and the parafacial zone in the brain stem—are involved in prompting SWS. When these cells switch on, it triggers a loss of consciousness.

After SWS, REM sleep begins. This mode is bizarre: a dreamer’s brain becomes highly active while the body’s muscles are paralyzed, and breathing and heart rate become erratic. The purpose of REM sleep remains a biological mystery, despite our growing understanding of its biochemistry and neurobiology.

We do know that a small group of cells in the brain stem, called the subcoeruleus nucleus, controls REM sleep. When these cells become injured or diseased, people do not experience the muscle paralysis associated with REM sleep, which can lead to REM sleep behavior disorder—a serious condition in which the afflicted violently act out their dreams.

~  Source ~

Saturn and its main ring system

 


astronomyblog | jellyfishjulie

In the early afternoon of September 13, 2017, the venerable and much-loved Cassini probe captured this final portrait of Saturn and its main ring system, before plummeting to fiery destruction in the planet’s hazy atmosphere just 48 hours later.

Credit: NASA/JPL/Caltech/SSI/Ian Regan