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.


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, 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.

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The Last Summer ‘Supermoon’ Of 2014 Is Also A Harvest Moon

Skywatchers, you’re in for a treat. Tonight’s "supermoon” is a pretty special one.

When the moon turns full on Monday, Sept. 8 at 9:38 p.m. EDT, it not only will become the last supermoon of the summer, but also this year's Harvest Moon – which is a full moon that occurs closest to the autumnal equinox.“

Learn more from the huffingtonpost.

The Astro Alphabet
By Ethan Siege

A is for Aurora, the Earth’s polar lights,
as the Sun’s hot electrons help color our nights.

B is for Black Hole, a star’s collapsed heart,
if you cross its horizon, you’ll never depart.

C is for Comet, with tails, ice, and dust,
a trip near the Sun makes skywatching a must!

D is for Dark Matter, the great cosmic glue
that holds clusters together, but not me and you!

E is for Eclipse, where the Moon, Earth and Sun
cast light-blocking shadows that can’t be outrun.

F is for Fusion, that powers the stars,
as nuclei join, their released light is ours!

G is for Galaxies, in groups and alone,
house billions of planets with lifeforms unknown.

H is for Hubble, for whom Earth’s no place;
a telescope like this belongs up in space.

I is for Ions, making nebulae glow;
as they find electrons, we capture the show.

J is for Jets, from a galaxy’s core,
if you feed them right, they’ll be active once more!

K is for Kepler, whose great laws of motion
keep planets on course in the great cosmic ocean.

L is for Libration, which makes our Moon rock,
it’s a trick of the orbit; it’s tidally locked!

M is for Meteors, which come in a shower,
if skies are just right, you’ll see hundreds an hour!

N is for Nebula, what forms when stars die,
this recycled fuel makes cosmic apple pie.

O is for Opaque, why the Milky Way’s dark,
these cosmic dust lanes make starlight appear stark!

P is for Pulsar, a spinning neutron star,
as the orbits tick by, we know just when we are.

Q is for Quasar, a great radio source,
accelerating matter with little remorse.

R is for Rings, all gas giants possess them,
even one found in another sun’s system!

S is for Spacetime, which curves due to matter,
this Universe-fabric can bend but won’t shatter!

T is for Tides, caused by gravity’s tune,
our oceans bulge out from the Sun and the Moon.

U is the Universe, our goal’s understanding,
with billions of galaxies, as spacetime’s expanding!

V is for Virgo, our nearest great cluster,
with thousands of galaxies, it’s a gut-buster!

W is for Wavelength, the energies of light,
that tell us what atoms are in stars just from sight!

X is for X-rays, high-energy light,
where bursts of new stars show an ionized might.

Y is the Year, where we orbit our Sun,
each planet’s is different; the Earth’s is just one.

Z is for Zenith, so gaze up at the sky!
The Universe is here; let’s learn what, how and why.

Source: Starts With A Bang!
Image credit: Galaxy Zoo’s writing tool


NASA Astronomy Picture of the Day 2016 March 16 

A Phoenix Aurora over Iceland 

All of the other aurora watchers had gone home. By 3:30 am in Iceland, on a quiet night last September, much of that night’s auroras had died down. Suddenly though, a new burst of particles streamed down from space, lighting up the Earth’s atmosphere once again. This time, unexpectedly, pareidoliacally, they created an amazing shape reminiscent of a giant phoenix. With camera equipment at the ready, two quick sky images were taken, followed immediately by a third of the land. The mountain in the background is Helgafell, while the small foreground river is called Kaldá, both located about 30 kilometers north of Iceland’s capital Reykjavik. Seasoned skywatchers will note that just above the mountain, toward the left, is the constellation of Orion, while the Pleiades star cluster is also visible just above the frame center. The new aurora lasted only a minute and would be gone forever – possibly dismissed as an embellished aberration – were it not captured in the featured, digitally-composed, image mosaic.


First Solar Eclipse of 2014 Thrills Skywatchers in Australia

The moon took a bite out of the sun in the first solar eclipse of the year on Tuesday (April 29), a celestial ballet visible from Australia that captivated stargazers despite cloudy weather.

Tuesday’s solar eclipse was a “ring of fire” annular eclipse, but only for an uninhabited swath of Antarctica. For observers in Australia, the moon appeared to cover about 65 percent of the sun, resulting in a striking partial solar eclipse at sunset.

Rare ‘Selenelion’ Possible on Wednesday’s Lunar Eclipse

Observers of Wednesday morning’s total lunar eclipse might be able to catch sight of an extremely rare cosmic sight.

On Oct. 8, Interested skywatchers should attempt to see the total eclipse of the moon and the rising sun simultaneously. The little-used name for this effect is called a “selenelion,” a phenomenon that celestial geometry says cannot happen. Learn more


Mars gears up for its closest approach to Earth in over a decade

“Relative to the stars in the sky, planets generally move slightly towards the east from night-to-night. But beginning tonight, Mars will move to the west, commencing retrograde motion, which continues until June 30th. This isn’t due to Mars changing its motion, but rather to Earth, orbiting inner to Mars, overtaking it due to Earth’s faster path around the Sun.”

Every two years, Earth passes Mars in orbit, as the inner, faster world overtakes the outer one. This year, it happens when Earth approaches aphelion, its farthest point from the Sun, while Mars approaches perihelion, or its closest approach. On May 30th, the two worlds pass within just 0.51 A.U. (76 million km) of one another, their closest encounter since 2005. While Mars will still appear as no more than a point to unaided human vision, telescopes will provide absolutely spectacular views during the next three months. If you miss it, you’ll have to wait two years for views this good, and then you won’t get them again until 2035.

Go get the whole story – and some amazing pictures – to start your week off right!


What is a lunar eclipse tetrad and where will you be able to see it [starting tonight]? | Video Credit: ScienceAtNASA | Image Credit: NASA/JPL-Caltech, & Joe Rao/

On April 15, 2014, an extraordinary series of total lunar eclipses will begin in the United States. This series, called a lunar eclipse tetrad, will result in four red moons over the course of a year and a half. NASA explains the significance behind this phenomenon, and sheds light on how the moon transforms into a bright red orb. Via TED-Ed

When and where it will be visible:

The first total lunar eclipse of 2014 occurs in the overnight hours tonight (April 14) and will be visible across most of North America, South America, Hawaii and parts of Alaska. Depending on your location, it begins either late tonight or in the wee hours of Tuesday, but as with every skywatching event, you can only see it if Mother Nature cooperates.

Tonight’s lunar eclipse runs from 12:53 a.m. EDT (0453 GMT) to about 6 a.m. EDT (1000 GMT). If bad weather spoils your view, or you live in Europe or elsewhere outside the visibility zone, you can always watch live webcasts of the total lunar eclipse on, courtesy of NASA, the Slooh community telescope, the Virtual Telescope Project.

What happens during lunar eclipses?

Lunar eclipses happen when the moon is in the full moon stage and passes through part or all of the Earth’s shadow, darkening the moon’s typically bright glow. During a total lunar eclipse, the moon is entirely immersed in Earth shadow, and can take on a dusky “blood red" colour due to the scattering of sunlight through the edges of Earth’s atmosphere. Such moons are sometimes nicknamed "Blood Moons.”

Tonight’s lunar eclipse is the first of four consecutive total eclipses of the moon between April 2014 and September 2015 in what scientists call a 

lunar eclipse “tetrad”

 series. The next total lunar eclipse will occur on Oct. 8 and is also expected to be visible from much of North America.


Read more about 2014’s Lunar Eclipse Tetrad: