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We've got a doubleheader of astronomical action Wednesday: The spring equinox, which marks the beginning of spring, along with the final "supermoon" of the year.  Both will occur on Wednesday: The equinox at 5:58 p.m. EDT and the full moon/supermoon less than four hours later at 9:43 p.m. EDT, EarthSky reported. The equinox is the precise moment the sun's rays shine directly on the equator. It's one of two days out of the year – the other being the autumnal equinox in September – when the Earth's axis is tilted neither toward nor away from the sun, resulting in roughly 12 hours of daylight and 12 hours of darkness almost everywhere on Earth. So it's an "equal night," which is where the word equinox originated: the two Latin words aequus (equal) and nox (night), according to the National Oceanic and Atmospheric Administration. Each day for the next three months, the sun will continue to get higher in the sky – and t...

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How high-speed stars escape the galaxy

Friday, March 15th 2019 12:17 PM

Stars bob and weave in and out of the Milky Way Galaxy’s spiral arms like cars speeding through rush-hour traffic. But a snapshot of the nighttime sky makes it appear that these luminaries are as fixed as the great pyramids of Egypt. Of the estimated 200 billion to 400 billion stars that call our galaxy home, however, a tiny fraction of hot, massive ones stand out. Gravitational interactions have revved them up to speeds double or even triple that of the Sun. These so-called hyper­velocity stars race through the Milky Way so quickly that they are destined to break free of the galaxy’s gravitational embrace.Our local solar neighborhood is in constant motion, participating in a mostly orderly flow shared by the vast majority of the stars revolving around the Milky Way’s center. But a small number of fast-moving suns break this overall pattern. Astronomers often find these “runaway stars” fleeing youthful clusters.Hypervelocity stars take these speeds...

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The Milky Way Galaxy contains billions of stars. Though the vast majority of these are bound to the galaxy by gravity, astronomers have found a few tens of stars that are not orbiting but instead fleeing our galaxy at extreme speeds. These hypervelocity stars have intrigued researchers for years, and now a new mysterious player has entered the game. LAMOST-HVS, the closest of these fast-moving stars to our Sun, has an origin story markedly different from the way we believed these stars get their kick out of the Milky Way. In a study led by researchers from the University of Michigan and published March 12 in the Astrophysical Journal, astronomers used data from the Magellan telescope in Chile and the European Space Agency’s Gaia satellite to wind back the clock and trace the trajectory of LAMOST-HVS, an 8.3-solar-mass star zipping away from the galaxy at more than 350 miles per second (568 kilometers per second). LAMOST-HVS is the closest hypervelocity star...

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Researchers have found two massive young stars nestled closer together than anything astronomers have seen so far. By studying PDS 27 and its companion, located about 8,000 light-years from Earth, astronomers hope to learn more about how stars like this form and evolve.Something like half the stars in our galaxy orbit in pairs, triplets, or even quadruple-star systems. And scientists suspect that nearly all stars may form in multiples before splitting apart as they age. This is because stars form in groups, with the massive clouds of dust and gas that give birth to stars – stellar nebulae – forming thousands of stars in brief periods. Often these stars are born close enough to orbit one another, and that’s why stellar twins and triplets are quite common in the universe. High-mass stars in particular, like PDS 27, are almost always born with companions.But even these sibling stars often orbit something like 1,000 astronomical units (AU; one AU is the average Earth-Sun...

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The Milky Way and the Andromeda Galaxy are the two biggest players in our galactic neighborhood. With each galaxy weighing in at roughly a trillion times the mass of the Sun, they serve as the gravitational anchors that prevent our Local Group — a collection of more than 50 galaxies — from flying apart. However, because these two behemoths are so massive, they're also destined to collide in some 4 billion years, give or take, which will throw our quiet corner of the cosmos into chaos.Though the notion of interacting galaxies seems like perfect fodder for science fiction, such collisions are not far-fetched; they actually occur quite frequently throughout the universe. In fact, researchers believe that most galaxies experience collisions and mergers at some point (or many points) during their lives. Over the years, astronomers have spotted dozens of pairs of galaxies in the midsts of mashups, and now, Hubble has captured yet another cosmic...

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The Sky This Week from March 8 to 17

Saturday, March 9th 2019 11:31 AM

Friday, March 8With an age of 4.5 billion years, “young” might not seem an appropriate word to describe our Moon. But tonight, you have an exceptional opportunity to see what astronomers call a “young Moon” — a slender crescent visible in the early evening sky. With New Moon having occurred just two days ago, only 5 percent of our satellite’s disk appears illuminated after sunset tonight. You can find the Moon about 10° above the western horizon an hour after sunset. You should notice an ashen light faintly illuminating the Moon’s dark side. This is “earthshine” — sunlight reflected by Earth that reaches the Moon and then reflects back to our waiting eyes. March is a particularly good month to view a young Moon. Luna gains altitude quickly from night to night because the ecliptic — the apparent path of the Sun across the sky that the Moon and planets follow closely — makes a steep angle to the western horizon...

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If you were transported to the Moon this very instant, you would surely and rapidly die. That’s because there’s no atmosphere, the surface temperature varies from a roasting 130 degrees Celsius (266 F) to a bone-chilling minus 170 C (minus 274 F). If the lack of air or horrific heat or cold don’t kill you then micrometeorite bombardment or solar radiation will. By all accounts, the Moon is not a hospitable place to be.Yet if human beings are to explore the Moon and, potentially, live there one day, we’ll need to learn how to deal with these challenging environmental conditions. We’ll need habitats, air, food and energy, as well as fuel to power rockets back to Earth and possibly other destinations. That means we’ll need resources to meet these requirements. We can either bring them with us from Earth – an expensive proposition – or we’ll need to take advantage of resources on the Moon itself. And that’s where the idea o...

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When New Horizons flew past Pluto and its moon Charon in 2015, it took a lot of pictures. From studying those images, scientists have recently realized that while both bodies are covered in craters, almost none of those craters are small, meaning there may not be many small bodies around to smash into them. This changes astronomers’ views of the Kuiper Belt, the region of small – but apparently not too small – rocky and icy bodies of which Pluto is a part.   No Tiny Craters Astronomers looked at images taken from all over Pluto and Charon, but focused their most detailed investigations on Charon’s Vulcan Planitia, a broad plain that was resurfaced early in Charon’s history. The smooth icy surface makes it easy to count craters, though researchers point out that they get similar – if less clear – results from other regions on Charon and Pluto. They found that while there are plenty of large and medium-sized craters, there a...

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The Sky This Week from March 1 to 10

Saturday, March 2nd 2019 02:30 PM

Friday, March 1The variable star Algol in Perseus reaches minimum brightness at 7:19 p.m. EST, when it shines at magnitude 3.4. If you start viewing as soon as darkness falls, you can watch it more than triple in brightness (to magnitude 2.1) over the course of about five hours. This eclipsing binary star runs through a cycle from minimum to maximum and back every 2.87 days. Algol appears high in the west after sunset and sinks slowly toward the northwestern horizon after midnight.Saturday, March 2If you are up before dawn this morning, you’ll see a slender crescent Moon rising less than 5° to the right of brilliant Venus. The two clear the horizon before 5 a.m. local time and climb 10° high an hour before sunrise. Venus shines at magnitude –4.1 against the background stars on the Sagittarius-Capricornus border. (The planet crosses from the former to the latter constellation today.) If you target Venus through a telescope, you’ll see a disk that spans 15" an...

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Rusty Schweickart remembers Apollo 9

Friday, March 1st 2019 12:41 PM

Before Neil Armstrong set foot on the Moon, becoming the first human to step on another world, we had to be ready. A big part of the readiness came earlier that year, when three astronauts flew in Earth orbit during NASA’s Apollo 9 mission. This 10-day adventure commenced March 3, 1969, less than five months ahead of the Moon landing, and it was a critical milestone. Apollo 9 marked the first complete test of the Apollo system. Commander Jim McDivitt, along with Command Module Pilot David Scott and Lunar Module Pilot Russell “Rusty” Schweickart, put all the systems through their paces.   The mission was a turning point for several reasons. It was the first live orbital test of the lunar module (LM), the lander that would carry two astronauts to the Moon’s surface. The rendezvous and docking procedures between the LM and the command/service module were also tested. And it offered practice runs for astronauts to walk in space in order to conduct mainten...

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