On Nov. 11, Earthlings will be treated to a rare cosmic event — a Mercury transit.
For about five and a half hours on Monday, Nov. 11 — from about 7:35 a.m. EST to 1:04 p.m. EST — Mercury will be visible from Earth as a tiny black dot crawling across the face of the Sun. This is a transit and it happens when Mercury lines up just right between the Sun and Earth.
Mercury transits happen about 13 times a century. Though it takes Mercury only about 88 days to zip around the Sun, its orbit is tilted, so it’s relatively rare for the Sun, Mercury and Earth to line up perfectly. The next Mercury transit isn’t until 2032 — and in the U.S., the next opportunity to catch a Mercury transit is in 2049!
How to watch
Our Solar Dynamics Observatory satellite, or SDO, will provide near-real time views of the transit. SDO keeps a constant eye on the Sun from its position in orbit around Earth to monitor and study the Sun’s changes, putting it in the front row for many eclipses and transits.
If you’re thinking of watching the transit from the ground, keep in mind that it is never safe to look directly at the Sun. Even with solar viewing glasses, Mercury is too small to be easily seen with the unaided eye. Your local astronomy club may have an opportunity to see the transit using specialized, properly-filtered solar telescopes — but remember that you cannotuse a regular telescope or binoculars in conjunction with solar viewing glasses.
Transits in other star systems
Transiting planets outside our solar system are a key part of how we look for exoplanets.
Our Transiting Exoplanet Survey Satellite, or TESS, is NASA’s latest planet-hunter, observing the sky for new worlds in our cosmic neighborhood. TESS searches for these exoplanets, planets orbiting other stars, by using its four cameras to scan nearly the whole sky one section at a time. It monitors the brightness of stars for periodic dips caused by planets transiting those stars.
This is similar to Mercury’s transit across the Sun, but light-years away in other solar systems! So far, TESS has discovered 29 confirmed exoplanets using transits — with over 1,000 more candidates being studied by scientists!
on the first day of class my astronomy professor asked us why the night sky was dark. if our universe is infinite, how can there be spaces between the stars? he didn’t answer the question until the last day– because our universe is relatively young, and is still growing. it is finite. not enough stars or galaxies have been formed to fill up the entire night sky.
but what that means to me is that somewhere, in an older universe, the night sky looks like a tapestry of diamonds. somewhere darkness is pale white and glittering. imagine being so surrounded. i haven’t gotten that image out of my head ever since– you could never navigate under such a sky but god it sounds lovely
We launched our Spitzer Space Telescope into orbit around the Sunday on Aug. 25, 2003. Since then, the observatory has been lifting the veil on the wonders of the cosmos, from our own solar system to faraway galaxies, using infrared light.
Thanks to Spitzer, scientists were able to confirm the presence of seven rocky, Earth-size planets in the TRAPPIST-1 system. The telescope has also provided weather maps of hot, gaseous exoplanets and revealed a hidden ring around Saturn. It has illuminated hidden collections of dust in a wide variety of locations, including cosmic nebulas (clouds of gas and dust in space), where young stars form, and swirling galaxies. Spitzer has additionally investigated some of the universe’s oldest galaxies and stared at the black hole at the center of the Milky Way.
In honor of Spitzer’s Sweet 16 in space, here are 16 amazing images from the mission.
Giant Star Makes Waves
This Spitzer image shows the giant star Zeta Ophiuchi and the bow shock, or shock wave, in front of it. Visible only in infrared light, the bow shock is created by winds that flow from the star, making ripples in the surrounding dust.
The Seven Sisters Pose for Spitzer
The Pleiades star cluster, also known as the Seven Sisters, is a frequent target for night sky observers. This image from Spitzer zooms in on a few members of the sisterhood. The filaments surrounding the stars are dust, and the three colors represent different wavelengths of infrared light.
Young Stars in Their Baby Blanket of Dust
Newborn stars peek out from beneath their blanket of dust in this image of the Rho Ophiuchi nebula. Called “Rho Oph” by astronomers and located about 400 light-years from Earth, it’s one of the closest star-forming regions to our own solar system.
The youngest stars in this image are surrounded by dusty disks of material from which the stars — and their potential planetary systems — are forming. More evolved stars, which have shed their natal material, are blue.
The Infrared Helix
Located about 700 light-years from Earth, the eye-like Helix nebula is a planetary nebula, or the remains of a Sun-like star. When these stars run out of their internal fuel supply, their outer layers puff up to create the nebula. Our Sun will blossom into a planetary nebula when it dies in about 5 billion years.
The Tortured Clouds of Eta Carinae
The bright star at the center of this image is Eta Carinae, one of the most massive stars in the Milky Way galaxy. With around 100 times the mass of the Sun and at least 1 million times the brightness, Eta Carinae releases a tremendous outflow of energy that has eroded the surrounding nebula.
Spitzer Spies Spectacular Sombrero
Located 28 million light-years from Earth, Messier 104 — also called the Sombrero galaxy or M104 — is notable for its nearly edge-on orientation as seen from our planet. Spitzer observations were the first to reveal the smooth, bright ring of dust (seen in red) circling the galaxy.
Spiral Galaxy Messier 81
This infrared image of the galaxy Messier 81, or M81, reveals lanes of dust illuminated by active star formation throughout the galaxy’s spiral arms. Located in the northern constellation of Ursa Major (which includes the Big Dipper), M81 is also about 12 million light-years from Earth.
Spitzer Reveals Stellar Smoke
Messier 82 — also known as the Cigar galaxy or M82 — is a hotbed of young, massive stars. In visible light, it appears as a diffuse bar of blue light, but in this infrared image, scientists can see huge red clouds of dust blown out into space by winds and radiation from those stars.
A Pinwheel Galaxy Rainbow
This image of Messier 101, also known as the Pinwheel Galaxy or M101, combines data in the infrared, visible, ultraviolet and X-rays from Spitzer and three other NASA space telescopes: Hubble, the Galaxy Evolution Explorer’s Far Ultraviolet detector (GALEX) and the Chandra X-Ray Observatory. The galaxy is about 70% larger than our own Milky Way, with a diameter of about 170,000 light-years, and sits at a distance of 21 million light-years from Earth. Read more about its colors here.
The first ripple appears as a bright blue outer ring around the larger object, radiating ultraviolet light visible to GALEX. The clumps of pink along the outer blue ring are X-ray (observed by Chandra) and ultraviolet radiation.
Spitzer and Hubble Create Colorful Masterpiece
Located 1,500 light-years from Earth, the Orion nebula is the brightest spot in the sword of the constellation Orion. Four massive stars, collectively called the Trapezium, appear as a yellow smudge near the image center. Visible and ultraviolet data from Hubble appear as swirls of green that indicate the presence of gas heated by intense ultraviolet radiation from the Trapezium’s stars. Less-embedded stars appear as specks of green, and foreground stars as blue spots. Meanwhile, Spitzer’s infrared view exposes carbon-rich molecules called polycyclic aromatic hydrocarbons, shown here as wisps of red and orange. Orange-yellow dots are infant stars deeply embedded in cocoons of dust and gas.
A Space Spider Watches Over Young Stars
Located about 10,000 light-years from Earth in the constellation Auriga, the Spider nebula resides in the outer part of the Milky Way. Combining data from Spitzer and the Two Micron All Sky Survey (2MASS), the image shows green clouds of dust illuminated by star formation in the region.
North America Nebula in Different Lights
This view of the North America nebula combines visible light collected by the Digitized Sky Survey with infrared light from NASA’s Spitzer Space Telescope. Blue hues represent visible light, while infrared is displayed as red and green. Clusters of young stars (about 1 million years old) can be found throughout the image.
Spitzer Captures Our Galaxy’s Bustling Center
This infrared mosaic offers a stunning view of the Milky Way galaxy’s busy center. The pictured region, located in the Sagittarius constellation, is 900 light-years agross and shows hundreds of thousands of mostly old stars amid clouds of glowing dust lit up by younger, more massive stars. Our Sun is located 26,000 light-years away in a more peaceful, spacious neighborhood, out in the galactic suburbs.
The Eternal Life of Stardust
The Large Magellanic Cloud, a dwarf galaxy located about 160,000 light-years from Earth, looks like a choppy sea of dust in this infrared portrait. The blue color, seen most prominently in the central bar, represents starlight from older stars. The chaotic, bright regions outside this bar are filled with hot, massive stars buried in thick blankets of dust.
A Stellar Family Portrait
In this large celestial mosaic from Spitzer, there’s a lot to see, including multiple clusters of stars born from the same dense clumps of gas and dust. The grand green-and-orange delta filling most of the image is a faraway nebula. The bright white region at its tip is illuminated by massive stars, and dust that has been heated by the stars’ radiation creates the surrounding red glow.
Managed by our Jet Propulsion Laboratory in Pasadena, California, Spitzer’s primary mission lasted five-and-a-half years and ended when it ran out of the liquid helium coolant necessary to operate two of its three instruments. But, its passive-cooling design has allowed part of its third instrument to continue operating for more than 10 additional years. The mission is scheduled to end on Jan. 30, 2020.
Stellar winds are fast moving flows of material (protons, electrons and atoms of heavier metals) that are ejected from stars. These winds are characterised by a continuous outflow of material moving at speeds anywhere between 20 and 2,000 km/s.
In the case of the Sun, the wind ‘blows’ at a speed of 200 to 300 km/s from quiet regions, and 700 km/s from coronal holes and active regions.
The causes, ejection rates and speeds of stellar winds vary with the mass of the star. In relatively cool, low-mass stars such as the Sun, the wind is caused by the extremely high temperature (millions of degrees Kelvin) of the corona.
his high temperature is thought to be the result of interactions between magnetic fields at the star’s surface, and gives the coronal gas sufficient energy to escape the gravitational attraction of the star as a wind. Stars of this type eject only a tiny fraction of their mass per year as a stellar wind (for example, only 1 part in 1014 of the Sun’s mass is ejected in this way each year), but this still represents losses of millions of tonnes of material each second. Even over their entire lifetime, stars like our Sun lose only a tiny fraction of 1% of their mass through stellar winds.
In contrast, hot, massive stars can produce stellar winds a billion times stronger than those of low-mass stars. Over their short lifetimes, they can eject many solar masses (perhaps up to 50% of their initial mass) of material in the form of 2,000 km/sec winds.
These stellar winds are driven directly by the radiation pressure from photons escaping the star. In some cases, high-mass stars can eject virtually all of their outer envelopes in winds. The result is a Wolf-Rayet star.
Stellar winds play an important part in the chemical evolution of the Universe, as they carry dust and metals back into the interstellar medium where they will be incorporated into the next generation of stars.
On July 20, 1969, 109 hours and 42 minutes after launch, Neil Armstrong and Edwin ‘Buzz’ Aldrin entered the lunar lander ‘Eagle’, made a final check, and the Eagle undocked from the lunar orbiter ‘Columbia’, where the third member of the crew Michael Collins, stayed in orbit around the moon. Partially manually piloted by Armstrong, the Eagle landed 0 degrees, 41 minutes, 15 seconds north moon latitude and 23 degrees, 26 minutes east moon longitude. Armstrong stepped out, and Aldrin followed 20 minutes later: human beings stepped on the moon for the first time. The two men spent 21 hours and 26 minutes on its surface. One of the astounding aspects of the mission was the seeming simplicity of the technology used to get man to the moon. According to Oliver Gassmann, professor of Technology Management, the mobile phone in your pocket has one million times more memory than the Apollo 11’s computer. Same about the procesor: the latest phones typically have more than 100,000 times the processing power of the computer that landed man on the moon 50 years ago.
“It suddenly struck me that that tiny pea, pretty and blue, was the Earth. I put up my thumb and shut one eye, and my thumb blotted out the planet Earth. I didn’t feel like a giant. I felt very, very small.” –Neil Armstrong