Archives mensuelles : avril 2020

A Flow of Time

This surreal timelapse, landscape, panorama spans predawn, blue hour, and sunrise skies. Close to the start of planet Earth’s northern hemisphere spring, the flow of time was captured between 4:30 and 7:00 am from a location overlooking northern New Mexico’s Rio Grande Valley. In tracked images of the night sky just before twilight begins, the Milky Way is cast across the southern (right) edge of the panoramic frame. Toward the east, a range of short and long exposures resolves the changing brightness as the Sun rises over the distant peaks of the Sangre de Cristo Mountains. In between, exposures made during the spring morning’s tantalizing blue hour are used to blend the night sky and sunrise over the high desert landscape. via NASA https://ift.tt/3c7Qnc9

Country Sky versus City Sky

Dark skies are disappearing from the world. With modernization comes artificial lighting that brightens the night. While these lights allow modern humans to see, much light is wasted up into the sky. This light pollution not only wastes energy, but, when reflected by the Earth’s atmosphere back down, creates a nighttime brightness that disrupts wildlife and harms human health, while doing very little to prevent crime. Light pollution is also making a dark night sky a scarcity for new generations. While there is little that can be done in large cities, rural country areas could benefit from lighting that is fully shielded from exposing the night sky where it is not needed. The featured panorama contains 6 adjacent vertical segments taken from different locations across Slovakia — but with the same equipment and at the same time of night, and then subjected to the same digital post-processing. Although no stars are visible on the left-most city sky, the right-most country sky is magnificently dark. You can help protect the wonders of your night sky by favoring, when possible, dark sky friendly lightning. via NASA https://ift.tt/2XiAqf2

A Path North

What happens if you keep going north? The direction north on the Earth, the place on your horizon below the northern spin pole of the Earth — around which other stars appear to slowly swirl, will remain the same. This spin-pole-of-the-north will never move from its fixed location on the sky — night or day — and its height will always match your latitude. The further north you go, the higher the north spin pole will appear. Eventually, if you can reach the Earth’s North Pole, the stars will circle a point directly over your head. Pictured, a four-hour long stack of images shows stars trailing in circles around this north celestial pole. The bright star near the north celestial pole is Polaris, known as the North Star. The bright path was created by the astrophotographer’s headlamp as he zigzagged up a hill just over a week ago in Lower Saxony, Germany. The astrophotographer can be seen, at times, in shadow. Actually, the Earth has two spin poles — and much the same would happen if you started below the Earth’s equator and went south. via NASA https://ift.tt/39Pcoej

NGC 1672: Barred Spiral Galaxy from Hubble

Many spiral galaxies have bars across their centers. Even our own Milky Way Galaxy is thought to have a modest central bar. Prominently barred spiral galaxy NGC 1672, featured here, was captured in spectacular detail in an image taken by the orbiting Hubble Space Telescope. Visible are dark filamentary dust lanes, young clusters of bright blue stars, red emission nebulas of glowing hydrogen gas, a long bright bar of stars across the center, and a bright active nucleus that likely houses a supermassive black hole. Light takes about 60 million years to reach us from NGC 1672, which spans about 75,000 light years across. NGC 1672, which appears toward the constellation of the Dolphinfish (Dorado), has been studied to find out how a spiral bar contributes to star formation in a galaxy’s central regions. via NASA https://ift.tt/2ReQoTH

Color the Universe

Wouldn’t it be fun to color in the universe? If you think so, please accept this famous astronomical illustration as a preliminary substitute. You, your friends, your parents or children, can print it out or even color it digitally. While coloring, you might be interested to know that even though this illustration has appeared in numerous places over the past 100 years, the actual artist remains unknown. Furthermore, the work has no accepted name — can you think of a good one? The illustration, first appearing in a book by Camille Flammarion in 1888, is used frequently to show that humanity’s present concepts are susceptible to being supplanted by greater truths. via NASA https://ift.tt/2Xb30Pe

Venus and the Sisters

After wandering about as far from the Sun on the sky as Venus can get, the brilliant evening star is crossing paths with the sister stars of the Pleiades cluster. Look west after sunset and you can share the ongoing conjunction with skygazers around the world. Taken on April 2, this celestial group photo captures the view from Portal, Arizona, USA. Even bright naked-eye Pleiades stars prove to be much fainter than Venus though. Apparent in deeper telescopic images, the cluster’s dusty surroundings and familiar bluish reflection nebulae aren’t quite visible, while brighter Venus itself is almost overwhelming in the single exposure. And while Venus and the Sisters do look a little star-crossed, their spiky appearance is the diffraction pattern caused by multiple leaves in the aperture of the telephoto lens. The last similar conjunction of Venus and Pleiades occurred nearly 8 years ago. via NASA https://ift.tt/3dMwOYm

The Traffic in Taurus

There’s a traffic jam in Taurus lately. On April 1, this celestial frame from slightly hazy skies over Tapiobicske, Hungary recorded an impressive pile up toward the zodiacal constellation of the Bull and the Solar System’s ecliptic plane. Streaking right to left the International Space Station speeds across the bottom of the telescopic field of view. Wandering about as far from the Sun in planet Earth’s skies as it can get, inner planet Venus is bright and approaching much slower, overexposed at the right. Bystanding at the upper left are the sister stars of the Pleiades. No one has been injured in the close encounter though, because it really isn’t very close. Continuously occupied since November 2000, the space station orbits some 400 kilometers above the planet’s surface. Venus, currently the brilliant evening star, is almost 2/3 of an astronomical unit away. A more permanent resident of Taurus, the Pleiades star cluster is 400 light-years distant. via NASA https://ift.tt/2UXr6ub

Venus and the Pleiades in April

Venus is currently the brilliant evening star. Shared around world, in tonight’s sky Venus will begin to wander across the face of the lovely Pleiades star cluster. This digital sky map illustrates the path of the inner planet as the beautiful conjunction evolves, showing its position on the sky over the next few days. The field of view shown is appropriate for binocular equipped skygazers but the star cluster and planet are easily seen with the naked-eye. As viewed from our fair planet, Venus passed in front of the stars of the Seven Sisters 8 years ago, and will again 8 years hence. In fact, orbiting the Sun 13 Venus years are almost equal to 8 years on planet Earth. So we can expect our sister planet to visit nearly the same place in our sky every 8 years. via NASA https://ift.tt/39y8sy7

Asteroid or Potato

Is this asteroid Arrokoth or a potato? Perhaps, after all the data was beamed back to Earth from NASA’s robotic New Horizons spacecraft, the featured high resolution image of asteroid Arrokoth was constructed. Perhaps, alternatively, the featured image is of a potato. Let’s consider some facts. Arrokoth is the most distant asteroid ever visited and a surviving remnant of the early years of our Solar System. A potato is a root vegetable that you can eat. Happy April Fool’s Day from the folks at APOD! Although asteroid Arrokoth may look like a potato, in fact very much like the featured potato, Arrokoth (formerly known as Ultima Thule) is about 200,000 times wider and much harder to eat. via NASA https://ift.tt/2UQHooB