These Three Bright Nebulae Are Often Featured In Telescopic Tours Of The Constellation Sagittariusand

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a night with the stars will usually help

By: Jonah Reenders

The California Nebula.

Mercury is passing directly across the sun for the first time in nearly a decade.

The innermost planet of our solar system will look like a small, dark circle cutting across the sun’s disc. In the U.S., the transit began shortly after 7 a.m. ET on Monday and will continue for more than seven hours.

At least part of the transit, which only happens about 13 times every century, will be visible across the Americas, Europe, Africa and large portions of Asia.

If you’re hoping to watch it, eye protection is key. NASA stresses that “viewing this event safely requires a telescope or high-powered binoculars fitted with solar filters made of specially-coated glass or Mylar.”

You won’t be able to see the tiny dot of Mercury on its celestial crawl without magnification, NASA says.

Another option: Check out one of the multiple live-streaming events going on Monday. NASA says it will stream the transit here, here and here.

It’s not all about the show — transits like this one have historically been, and continue to be, important research opportunities for scientists. First observed in 1631, the transits were later used to “measure the distance between the Earth and the Sun,”NASA said.

Now, they provide scientists an opportunity to study the planets’ exospheres — the thin layer of gases that make up their atmosphere.

“When Mercury is in front of the sun, we can study the exosphere close to the planet,” NASA scientist Rosemary Killen said in a release from the Jet Propulsion Laboratory. “Sodium in the exosphere absorbs and re-emits a yellow-orange color from sunlight, and by measuring that absorption, we can learn about the density of gas there.”

Additionally, scientists have found that a transiting planet causes a drop in the sun’s brightness.

This phenomenon is “the main way we find planets outside the solar system,” NASA says.

The Kepler mission, which is searching for habitable planets, has found 1,041 planets to date using the transit method. The mission says it is able to determine the size of a planet by observing its transit.

Image Credit: NASA

Morning On Mars

 Martian sunrises, as seen by the HiRISE orbiter

The most color rich region of night sky, the Milky Way Core and Rho Ophiuchi Complex

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Carina Nebula clouds. So stunning.

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M7: Open Star Cluster in Scorpius : M7 is one of the most prominent open clusters of stars on the sky. The cluster, dominated by bright blue stars, can be seen with the naked eye in a dark sky in the tail of the constellation of the Scorpion . M7 contains about 100 stars in total, is about 200 million years old, spans 25 light-years across, and lies about 1000 light-years away. The featured wide-angle image was taken near the city of Belo Horizonte in Brazil. The M7 star cluster has been known since ancient times, being noted by Ptolemy in the year 130 AD. Also visible are a dark dust cloud on the lower right, and, in the background, literally millions of unrelated stars towards the Galactic center. via NASA

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Hubbles Variable Nebula

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