Stars And Dust Pillars In NGC 7822 From WISE.

By artist Kory Hubbell.

Mercury In the Spotlight

For more than seven hours on Monday, May 9, Mercury will be visible as a tiny black dot crossing the face of the sun. This rare event – which happens only slightly more than once a decade – is called a transit.

Although Mercury whips around the sun every 88 days – over four times faster than Earth – the three bodies rarely align. Because Mercury orbits in a plane 7 degrees tilted from Earth’s orbit, it usually darts above or below our line of sight to the sun. As a result, a Mercury transit happens only about 13 times a century. The last one was in 2006, and the next one isn’t until 2019.

When: On May 9, shortly after 7:00 a.m. EDT, Mercury will appear as a tiny black dot against a blazing backdrop, traversing the sun’s disk over seven and a half hours. Mercury will cross the edge of the sun (ingress) after 7:00 a.m. EDT. The mid-transit point will occur a little after 10:45 a.m. EDT, with egress around 2:30 p.m. EDT.

Where: Skywatchers in Western Europe, South America and eastern North America will be able to see the entirety of the transit. The entire 7.5-hour path across the sun will be visible across the Eastern U.S. – with magnification and proper solar filters – while those in the West can observe the transit in progress at sunrise.

Safety!

Unlike the 2012 Venus transit of the sun, Mercury is too small to be visible without magnification from a telescope or high-powered binoculars. Both must have safe solar filters made of specially-coated glass or Mylar; you can never look directly at the sun. We’re offering several avenues for the public to view the event without specialized and costly equipment, including images on NASA.gov, a one-hour NASA Television special, and social media coverage.

The Science…Why are Planetary Transits Important?

Transits like this allowed scientists in the 17th century to make the first estimates of Earth’s distance from the sun. Transit observations over the past few centuries have also helped scientists study everything from the atmosphere of Venus to the slight shifts in Mercury’s orbit that could only be explained by the theory of general relativity. Because we know Mercury’s size and location precisely, this transit will help scientists calibrate telescopes on solar observatories SDO, SOHO, and Hinode. 

Transits can also teach us more about planets – both in and out of our solar system. The Venus transit in 2012 provided observations of the planet’s atmosphere. Transits are also the main way we find planets outside the solar system, called exoplanets.

The transit method looks for a drop in the brightness of a star when a planet passes in front of it. This method will not find every planet – only those that happen to cross our line of sight from Earth to the star. But with enough sensitivity, the transit method through continuous monitoring is a great way to detect small, Earth-size planets, and has the advantage of giving us both the planet’s size (from the fraction of starlight blocked), as well as its orbit (from the period between transits). Our Kepler/K2 mission uses this method to find exoplanets, as will the Transiting Exoplanet Survey Satellites, or TESS, following its launch in 2017/2018. 

We will stream a live program on NASA TV and the agency’s Facebook page from 10:30 to 11:30 a.m. – an informal roundtable during which experts representing planetary, heliophysics and astrophysics will discuss the science behind the Mercury transit. Viewers can ask questions via Facebook and Twitter using #AskNASA.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com

NASA originally commissioned these posters for an exhibit at the Kennedy Space Center Visitor’s Complex in 2009. As part of their Journey to Mars, these versions are now available to everyone online. 

Credit: NASA/KSC

Haleakala Observatory atop a volcano

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Jupiter Ascending

1936 … coming soon! by James Vaughan

Infra-red Cassini imaging of Saturns rings casting a shadow on the planet

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This long-exposure photo shows a meteor streaking across the sky during the Perseid meteor shower in August. Regram @ausyouthspace

Astronomers discover dizzying spin of the Milky Way Halo

Astronomers at the University of Michigan’s College of Literature, Science, and the Arts (LSA) discovered for the first time that the hot gas in the halo of the Milky Way galaxy is spinning in the same direction and at comparable speed as the galaxy’s disk, which contains our stars, planets, gas, and dust. This new knowledge sheds light on how individual atoms have assembled into stars, planets, and galaxies like our own, and what the future holds for these galaxies.

“This flies in the face of expectations,” says Edmund Hodges-Kluck, assistant research scientist. “People just assumed that the disk of the Milky Way spins while this enormous reservoir of hot gas is stationary-but that is wrong. This hot gas reservoir is rotating as well, just not quite as fast as the disk.”

The new NASA-funded research using the archival data obtained by XMM-Newton, a European Space Agency telescope, was recently published in the Astrophysical Journal. The study focuses on our galaxy’s hot gaseous halo, which is several times larger than the Milky Way disk and composed of ionized plasma.

Read more ~ SpaceDaily

Image: Artist’s impression. Our Milky Way galaxy and its small companion galaxies are surrounded by a giant halo of million-degree gas (seen in blue in this artist’s rendition) that is only visible to X-ray telescopes in space. U-M astronomers discovered that this massive hot halo spins in the same direction as the Milky Way disk and at a comparable speed.    Credit: NASA/CXC/M. Weiss/Ohio State/A. Gupta et al.