Taken on February 6, this snowy mountain and skyscape was captured near Melchsee-Frutt, central Switzerland, planet Earth. The reddish daylight and blue tinted glow around the afternoon Sun are colors of the Martian sky, though. Of course both worlds have the same Sun. From Mars, the Sun looks only about half as bright and 2/3 the size compared to its appearance from Earth. Lofted from the surface of Mars, fine dust particles suspended in the thin Martian atmosphere are rich in the iron oxides that make the Red Planet red. They tend to absorb blue sunlight giving a red tinge to the Martian sky, while forward scattering still makes the light appear relatively bluish near the smaller, fainter Martian Sun. Normally Earth’s denser atmosphere strongly scatters blue light, making the terrestrial sky blue. But on February 6 a huge cloud of dust blown across the Mediterranean from the Sahara desert reached the Swiss Alps, dimming the Sun and lending that Alpine afternoon the colors of the Martian sky. By the next day, only the snow was left covered with reddish dust.
This was not a typical sun pillar. Just after sunrise two weeks ago in Providence, Rhode Island, USA, a photographer, looking out his window, was suddenly awestruck. The astonishment was caused by a sun pillar that fanned out at the top. Sun pillars, singular columns of light going up from the Sun, are themselves rare to see, and are known to be caused by sunlight reflecting from wobbling, hexagon-shaped ice-disks falling through Earth’s atmosphere. Separately, upper tangent arcs are known to be caused by sunlight refracting through falling hexagon-shaped ice-tubes. Finding a sun pillar connected to an upper tangent arc is extraordinary, and, initially, took some analysis to figure out what was going on. A leading theory is that this sun pillar was also created, in a complex and unusual way, by falling ice tubes. Few might believe that such a rare phenomenon was seen again if it wasn’t for the quick thinking of the photographer — and the camera on his nearby smartphone.
How hard is it to land safely on Mars? So hard that many more attempts have failed than succeeded. The next attempt will be on Thursday. The main problem is that the Martian atmosphere is too thick to ignore — or it will melt your spacecraft. On the other hand, the atmosphere is too thin to rely on parachutes — or your spacecraft will crash land. Therefore, as outlined in the featured video, the Perseverance lander will lose much of its high speed by deploying a huge parachute, but then switch to rockets, and finally, assuming everything goes right, culminate with a hovering Sky Crane that will slowly lower the car-sized Perseverance rover to the surface with ropes. It may sound crazy, but the Curiosity rover was placed on Mars using a similar method in 2012. From atmospheric entry to surface touch-down takes about seven minutes, all coordinated by an onboard computer because Mars is too far away for rapid interactive communication. During this time, humans on Earth will simply wait to hear if the landing was successful. Last week, UAE‘s Hope spacecraft successfully began orbiting Mars, followed a day later by the Chinese Tianwen-1 mission, which will likely schedule a landing of its own rover sometime in the next few months.
Starting Thursday, there may be an amazing new robotic explorer on Mars. Or there may be a new pile of junk. It all likely depends on things going correctly in the minutes after the Mars 2020 mission arrives at its new home planet and attempts to deploy the Perseverance rover. Arguably the most sophisticated landing yet attempted on the red planet, consecutive precision events will involve a heat shield, a parachute, several rocket maneuvers, and the automatic operation of an unusual device called a Sky Crane. Thursday’s Seven Minutes of Terror echo the landing of the Curiosity rover on Mars in 2012, as depicted in the featured video. If successful, the car-sized Perseverance rover will rest on the surface of Mars, soon to begin exploring Jezero Crater to better determine the habitability of this seemingly barren world to life — past, present, and future. Although multiple media outlets may cover this event, one way to watch these landing events unfold is on the NASA channel live on the web.
Would the Rosette Nebula by any other name look as sweet? The bland New General Catalog designation of NGC 2237 doesn’t appear to diminish the appearance of this flowery emission nebula, at the top of the image, atop a long stem of glowing hydrogen gas. Inside the nebula lies an open cluster of bright young stars designated NGC 2244. These stars formed about four million years ago from the nebular material and their stellar winds are clearing a hole in the nebula’s center, insulated by a layer of dust and hot gas. Ultraviolet light from the hot cluster stars causes the surrounding nebula to glow. The Rosette Nebula spans about 100 light-years across, lies about 5000 light-years away, and can be seen with a small telescope towards the constellation of the Unicorn (Monoceros).
Get out your red/blue glasses and float next to asteroid 433 Eros. Orbiting the Sun once every 1.8 years, the near-Earth asteroid is named for the Greek god of love. Still, its shape more closely resembles a lumpy potato than a heart. Eros is a diminutive 40 x 14 x 14 kilometer world of undulating horizons, craters, boulders and valleys. Its unsettling scale and unromantic shape are emphasized in this mosaic of images from the NEAR Shoemaker spacecraft processed to yield a stereo anaglyphic view. Along with dramatic chiaroscuro, NEAR Shoemaker’s 3-D imaging provided important measurements of the asteroid’s landforms and structures, and clues to the origin of this city-sized chunk of Solar System. The smallest features visible here are about 30 meters across. Beginning on February 14, 2000, historic NEAR Shoemaker spent a year in orbit around Eros, the first spacecraft to orbit an asteroid. Twenty years ago, on February 12 2001, it landed on Eros, the first ever landing on an asteroid’s surface. NEAR Shoemaker’s final transmission from the surface of Eros was on February 28, 2001.
This gorgeous island universe lies about 85 million light-years distant in the southern constellation Fornax. Inhabited by young blue star clusters, the tightly wound spiral arms of NGC 1350 seem to join in a circle around the galaxy’s large, bright nucleus, giving it the appearance of a cosmic eye. In fact, NGC 1350 is about 130,000 light-years across. That makes it as large or slightly larger than the Milky Way. For earth-based astronomers, NGC 1350 is seen on the outskirts of the Fornax cluster of galaxies, but its estimated distance suggests that it is not itself a cluster member. Of course, the bright spiky stars in the foreground of this telescopic field of view are members of our own spiral Milky Way galaxy.
In brush strokes of interstellar dust and glowing gas, this beautiful skyscape is painted across the plane of our Milky Way Galaxy near the northern end of the Great Rift and the constellation Cygnus the Swan. Composed over a decade with 400 hours of image data, the broad mosaic spans an impressive 28×18 degrees across the sky. Alpha star of Cygnus, bright, hot, supergiant Deneb lies at the left. Crowded with stars and luminous gas clouds Cygnus is also home to the dark, obscuring Northern Coal Sack Nebula and the star forming emission regions NGC 7000, the North America Nebula and IC 5070, the Pelican Nebula, just left and a little below Deneb. Many other nebulae and star clusters are identifiable throughout the cosmic scene. Of course, Deneb itself is also known to northern hemisphere skygazers for its place in two asterisms, marking a vertex of the Summer Triangle, the top of the Northern Cross.
Why do stars twinkle? Our atmosphere is to blame as pockets of slightly off-temperature air, in constant motion, distort the light paths from distant astronomical objects. Atmospheric turbulence is a problem for astronomers because it blurs the images of the sources they want to study. The telescope featured in this image, located at ESO��������s Paranal Observatory, is equipped with four lasers to combat this turbulence. The lasers are tuned to a color that excites atoms floating high in Earth’s atmosphere — sodium left by passing meteors. These glowing sodium spots act as artificial stars whose twinkling is immediately recorded and passed to a flexible mirror that deforms hundreds of times per second, counteracting atmospheric turbulence and resulting in crisper images. The de-twinkling of stars is a developing field of technology and allows, in some cases, Hubble–class images to be taken from the ground. This technique has also led to spin-off applications in human vision science, where it is used to obtain very sharp images of the retina.
It somehow survived an explosion that would surely have destroyed our Sun. Now it is spins 30 times a second and is famous for the its rapid flashes. It is the Crab Pulsar, the rotating neutron star remnant of the supernova that created the Crab Nebula. A careful eye can spot the pulsar flashes in the featured time-lapse video, just above the image center. The video was created by adding together images taken only when the pulsar was flashing, as well as co-added images from other relative times. The Crab Pulsar flashes may have been first noted by an unknown woman attending a public observing night at the University of Chicago in 1957 — but who was not believed. The progenitor supernova explosion was seen by many in the year 1054 AD. The expanding Crab Nebula remains a picturesque expanding gas cloud that glows across the electromagnetic spectrum. The pulsar is now thought to have survived the supernova explosion because it is composed of extremely-dense quantum-degenerate matter.