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Yahoo
5 days ago
- Science
- Yahoo
See Venus, the moon and fiery star Aldebaran form a dawn triangle this weekend
When you buy through links on our articles, Future and its syndication partners may earn a commission. One of the brightest and most colorful stars in the sky and the most brilliant planet are on stage in the early morning dawn sky this weekend and will be joined by the moon on Monday morning. The star in question is Aldebaran, a first-magnitude star that shines with a distinct orange hue and marks the right eye of Taurus, the Bull. The brilliant planet is, of course, Venus, which outshines Aldebaran by almost five magnitudes or a light ratio difference of almost 100-fold. At this particular moment in time, both star and planet can be seen roughly one-quarter of the way up from the eastern horizon, roughly 45 minutes before sunrise. Venus, a dazzling morning "star," rises about an hour prior to the first light of dawn and shines low in the east-northeast as dawn brightens. On Monday morning, you'll also see a delicately thin (14 percent illuminated) crescent moon hovering approximately 8 degrees above Venus. Your clenched fist held at arm's length measures roughly 10 degrees in width, so on Monday morning, the slender lunar sliver will appear almost "one fist" above Venus. In a telescope, Venus is a disappointment: just a tiny, gibbous blob, 72 percent illuminated by the sun. It has shrunk and become more nearly round in recent months as it has swung far around to the back side of the sun as seen from Earth. TOP TELESCOPE PICK Want to see Venus, the moon, and Aldebaran together? The Celestron NexStar 8SE is ideal for beginners wanting quality, reliable and quick views of celestial objects. For a more in-depth look at our Celestron NexStar 8SE review. And situated well to the right of both Venus and the moon will be Aldebaran. The trio will appear to form a broad isosceles triangle with Venus marking the vertex angle, while Aldebaran and the moon form the base of the triangle. It will not be a particularly "tight" array, but still should be attractive enough to catch the attention of early risers. With the reappearance of Aldebaran, it is also a gentle reminder that while we are not yet at the midpoint of summer, the colder nights of fall and winter will be looming in the months to come. Aldebaran is crossing the meridian at midnight around Thanksgiving ... and at around 9 p.m. in mid-January. Who knows? By then, some of you might be shoveling snow. So take advantage of this week's opportunity to see not only an out-of-season winter star, but Venus as well, while they both "flirt" with a waning crescent moon. Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for Natural History magazine, Sky and Telescope and other publications.
Yahoo
5 days ago
- Science
- Yahoo
A vast shadow will sweep over Saturn's cloud tops early on July 18: Here's how to see it
When you buy through links on our articles, Future and its syndication partners may earn a commission. Early risers will get a rare opportunity to see something extraordinary in the early hours of July 18 — the dark shadow of Saturn's largest moon, Titan, sweeping across the planet's cloud tops. Once every 15 years, Saturn's tilted orbit brings its iconic rings — and Titan's orbital path — into an edge-on alignment with Earth. This event, known as a ring-plane crossing, heralds the onset of a season of dramatic 'shadow transits', as Titan's vast umbral silhouette periodically sweeps across the gas giant's surface. "Sighting a shadow transit of Titan for an amateur astronomer is somewhat the equivalent of a fisherman hooking and reeling in a particularly large or elusive fish," Hayden Planetarium instructor and lecturer Joe Rao told in an email. "It is so unusual a sight that doesn't happen very often, which is why even veteran skywatchers are excited at the possibility of making such a sighting." When is Titan's shadow transit? Titan's next shadow transit will get underway at 3 a.m. EDT (0700 GMT) on July 18, at which time the moon's dark outline will be visible slowly progressing across Saturn's cloudy disk, according to Sky and Telescope. Look for Saturn in the southeastern sky, just below the stars of the constellation Pisces shining like a bright star to the naked eye, with the moon in the east. Observers in the U.S. will have a good view of the first two hours of the shadow transit, but by the time Titan's shadow leaves Saturn's disk at 8:05 a.m. EDT (12:05 GMT), the brightening dawn will overpower the view. How powerful does a telescope need to be to spot Titan's shadow? At the time of the shadow transit, Titan and Saturn will be separated by approximately 846 million miles (1.36 billion kilometers) from Earth — far beyond the capabilities of the naked eye or binoculars, but well within reach of many amateur telescopes. We asked Rao for guidance on the kind of scope needed to view Titan's shadow transit. "An 8-inch telescope at 200-power or a 10-inch telescope at 250-power should provide a good view of Titan's shadow, especially on a night of good seeing," Rao explained. To calculate the magnifcation of your telescope, you need only divide its focal length by the focal length of your chosen eyepiece. For example, a 1000 mm telescope with a 10 mm eyepiece yields 100-power magnification. Rao also emphasised that stable atmospheric conditions are crucial to obtaining a clear view. This becomes more important when using higher power with a smaller aperture scope. It's best to use one-half magnification/power when viewing distant objects to avoid them appearing to "boil", or "scintilate" when viewed through the eyepiece. "At least 200-power is necessary for getting a reasonably good view of the dark 'shadow dot' projected on Saturn's disk," continued Rao. "The general rule of thumb is to utilize 50-power for every inch of aperture of the telescope objective, or mirror. So, for a 4-inch telescope, the maximum magnification to be used is 200-power, which is considered the limit for a telescope of that size." When are the next Titan shadow transits? After the July 18 event, five more Titan shadow transits will be visible from Earth. Each occurs roughly16 days after the last — a result of Titan's 16-day orbital period — and starting progressively earlier in the night for viewers in the U.S. Date Start End Aug 3 2:25 a.m. 7:04 a.m. Aug 19 1:52 a.m. 6:00 a.m. Sept 4 1:25 a.m. 4:50 a.m. Sept 20 1:09 a.m. 3:34 a.m. Oct 6 1:32 a.m. The next transit after this week will begin at 2:25 a.m. (0625 GMT) on August 3, while the last chance to catch the moon's shadow fall on Saturn will take place on October 6. After the October event, stargazers will have to wait another 15 years before the next ring crossing brings Titan — and its shadow — into alignment once more! Titan's shadow through the eyes of the Cassini spacecraft Without question, the most spectacular views of a Titan shadow transit came courtesy of NASA's Cassini spacecraft, which witnessed the moon's dark outline fall over Saturn's cloud surface in November 2009, while it travelled a mere 1.3 million miles (2.1 million km) from the colossal gas giant. Cassini has long since found its resting place beneath the cloud surface of Saturn, but amateur astronomers will have an opportunity to follow in Cassini's steps later this week and witness the next Titan shadow transit for themselves when it takes place on July 18. "Though we, living in the 21st century, have grown accustomed to seeing the Saturnian system through the eyes of Cassini, there still remains the thrill of witnessing, with one's own eyes, a major celestial event in the life of another planet a billion miles away," Carolyn Porco, planetary scientists and imaging team leader for NASA's Cassini mission told in an email. Editor's Note: If you would like to share your images of the Titan shadow transit with readers, then please send your photo(s), comments, and your name and location to spacephotos@ Solve the daily Crossword
National Geographic
10-07-2025
- Science
- National Geographic
Manhattanhenge is here again. How to see New York City's best sunset.
Prepare for social media's favorite sunset. On Friday and Saturday evening, July 11 and 12, the sun will line up perfectly with Manhattan's grid, turning the city's streets into glowing corridors of light. This rare and radiant moment, called Manhattanhenge, provides picture perfect views straight to New Jersey. New Yorkers can catch it both nights around 8:20 p.m., weather permitting. Manhattanhenge was named by astrophysicist and National Geographic Explorer Neil deGrasse Tyson, who was inspired by Stonehenge in Wiltshire, England. As head of the American Museum of Natural History's Hayden Planetarium, he began calculating the dates in the late 1990s . He coined the term in 2002, according to The New York Times , though there are references to ' solar grid day ' going back to the '80s. 'Manhattanhenge is 'astronomy in your face,'' says Jackie Faherty, an astrophysicist at the American Museum of Natural History , who now calculates the event's dates. The spectacle is possible thanks to Manhattan's 19th-century street grid, which was designed with 90-degree angles. While many people assume the sun sets due west each evening, it actually only sets due west twice a year, on the spring and fall equinoxes. During the rest of the year, the sunset drifts slightly north across the horizon until the summer solstice and then heads south again. If New York 's grid had been oriented due north, Manhattanhenge would coincide with the equinoxes. But because the grid is tilted about 30 degrees east from geographic north, it happens on different, 'Manhattanhenge' days. For those in New York this week, the best places to see Manhattanhenge are: 14th Street; 23rd Street; 34th Street; 42nd Street and 57th Street. What you'll see slightly differs depending on the day you go look. On July 11 the full disc of the sun will hover over the horizon and then on July 12 only half of the sun will kiss the city streets. This week's solar show is actually a repeat performance as Manhattanhenge also took place earlier this year on May 28 and 29. If you miss Manhattanhenge's sunset this year, but are an early-riser, then you can try to catch 'Reverse Manhattanhenge' when the sunrise is framed by New York's buildings November 28 and 29 (and again on January 11 and 12), according to Faherty. For Faherty, Manhattanhenge is a moment to reflect on how humanity and astronomy have long been intertwined. 'Astronomy used to be the science that helped guide people's lives. We used the stars to navigate, to tell time, and to know what season we were entering and existing,' she says. 'I think now, maybe more than ever, it's important for people to understand how much science guides their lives and how important it is to use scientific thinking in your everyday life.'
Scientific American
19-06-2025
- Science
- Scientific American
Gaia's Long Goodbye
This observatory has probably been the most transformative astronomy project of the 21st century, but there's a good chance you've never heard of it. Just last week, for instance, the Hayden Planetarium at the American Museum of Natural History (AMNH) in New York City debuted a new 'space show' called Encounters in the Milky Way —and this often overlooked spacecraft is its scientific superstar. But you're more likely to know about actor Pedro Pascal's narration in the show than you are to be familiar with the single space mission that serves as the presentation's backbone. The observatory is called Gaia. And, like so many good things, you wouldn't really miss it until it's gone—and now it is. Launched in 2013 by the European Space Agency (ESA), it ceased operations this past March, when it used what little fuel it had left to steer into a graveyard orbit around the sun. From its station in a quiescent region of deep space more than 1.6 million kilometers from Earth, Gaia's mission was, in essence, quite simple: it was designed to give us a better sense of where we are—a celestial 'reference frame' on overlapping interplanetary, interstellar and intergalactic scales. To do that, it used twin sky-sweeping telescopes and three instruments, including a billion-pixel camera, to painstakingly measure the distances, positions, motions, and more of about two billion celestial objects, most of them stars in our own galaxy. It made some three trillion observations in all, producing (among many other things) the largest, most precise three-dimensional map of the Milky Way ever made. On supporting science journalism If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today. 'Gaia was our best galactic cartographer, and I sometimes say that Encounters in the Milky Way is my love letter to it,' says Jackie Faherty, a senior research scientist at the AMNH, who curated the new space show and regularly works with Gaia data. 'It turns out you can learn a lot by determining where and how far off the stars are from you—and especially by how they are moving.... Gaia's creation of this map is something we all should celebrate because it's just as iconic and useful as the maps of Earth we all see in school or pull up on Google. Looking at it, you can find and explore all sorts of different things you want to know.' From Gaia's map, more than 13,000 peer-reviewed studies have already emerged, and many have concerned the fundamental structure and deep history of the Milky Way. Thanks to Gaia, scientists now can better gauge the amount of dark matter within our galaxy and have been able to track the Milky Way's growth and evolution across eons via relic streams of stars strewn from ancient mergers with other, smaller galaxies. 'Stars retain memories of their origins in their ages, motions and chemical compositions—all of which Gaia measured,' says Amina Helmi, an astronomer at the Kapteyn Astronomical Institute in the Netherlands. She and her colleagues used the mission's data to discover evidence of a major galactic merger that, some 10 billion years ago, shaped our home galaxy into the Milky Way we know today. 'With all that information, it was like a veil being lifted…. We could suddenly perform what's sometimes called 'galactic archaeology,' reconstructing the Milky Way's history to see when and how this merger happened with another, smaller galaxy that was about a third to a quarter of our galaxy's mass.... Gaia allows us to look billions of years into the Milky Way's history—before our solar system even formed—to see what actually happened back then, which is absolutely amazing.' Tracing perturbations from one more recent and ongoing merger, astronomers have even managed to reveal an apparent warp in the Milky Way's disk, offering a new twist—literally—on the classic image of our cosmic home. At smaller scales, the spacecraft has refined the orbits of more than 150,000 asteroids, surveilling hundreds of them to see if they have their own moons. It has spied hints of thousands of worlds and even a few black holes orbiting other stars. At larger scales, it has helped estimate the expansion rate of the universe, and it has also teased out the subtle tugging of the Milky Way's heart upon the solar system across tens of thousands of light-years. Gaia's sprawling cosmic reckoning is now a cornerstone for most state-of-the-art Earth- and space-based telescopes, which rely on the mission's target-dense celestial map to orient and calibrate their own observations and operations. Whether it's NASA's James Webb Space Telescope, ESA's Euclid mission, the ground-based, U.S.-built Vera C. Rubin Observatory or Europe's under-construction Extremely Large Telescope, practically all of the world's most exciting starlight-gathering telescopes will, in some sense, be guided by Gaia. And stunningly, the best is yet to come. More than two thirds of the mission's treasure trove of data is still under wraps. It is being prepared in a time-consuming process for two major upcoming milestones: about half of Gaia's total data are targeted for release next year, and the mission's full data are set to arrive no earlier than 2030. But because it didn't beam back images ready-made for lush wall posters and desktop backgrounds, Gaia was destined from the start to be 'criminally under-recognized outside astronomy,' says Mark McCaughrean, an astronomer and former senior adviser to ESA. 'And because Gaia provided utterly essential, if mundane, information such as precise stellar distances, it's been doomed with this curse of simultaneous ubiquity and obscurity as many people use its data but take it for granted as just 'coming from a catalog.'' Anthony Brown, an astronomer at Leiden University in the Netherlands, who leads the mission's data processing and analysis group, puts it most succinctly: 'For astronomers, Gaia has become almost like the air you breathe,' he says. At the heart of Gaia's mapmaking is a technique called astrometry, the measurement of celestial positions and motions in the plane of the sky. Paired with a phenomenon called parallax—the apparent shift of an object's position when viewed from two vantage points—astronomers can use Gaia for determining distances, too. You can see the parallax effect with your own two eyes: hold your thumb out at arm's length and watch as it appears to jump around as you blink one eye and then the other. The closer the object is, the bigger its displacement will be. And the bigger your baseline is between two vantage points, the smaller the displacement will be that you can discern. Your eyes have a baseline of about six centimeters; Gaia's was 300 million kilometers, set by the opposite sides of Earth's orbit around the sun. A Gaia predecessor, ESA's Hipparcos mission, used that same gigantic baseline to survey the sky from 1989 until it ran out of fuel in 1993. But the technology of the time limited Hipparcos's astrometric reckoning to a precision of about one milliarcsecond, with high-quality measurements only for about 100,000 objects within about 200 parsecs (650 light-years) of the solar system. (A single arc second is a very small angular slice of the heavens, making Hipparcos's milliarcsecond precision all the more noteworthy. The moon, for instance, takes up about 1,800 arc seconds in Earth's sky.) As impressive as Hipparcos was, Gaia shattered the records set by its precursor—although not without challenges, such as precision-threatening sprays of stray light that leaked around the edges of the spacecraft's sun shield and through a hole punched by an errant micrometeoroid. But ultimately, Brown says, Gaia's measurements achieved on the order of 100 times greater precision—reaching about 10 microarcseconds. And within the Milky Way, the spacecraft's view encompassed 100 times more volume and included 10 times more targets. The numbers underpinning Gaia are so alien to everyday experience that they border on nonsensical, says Michael Perryman, a former ESA researcher, who has served as project scientist for Hipparcos and Gaia and played a crucial developmental role for both missions. He likens Hipparcos's precision to discerning a second's worth of growth of a human hair from a distance of one meter. Gaia's 100-times-better view, he says, is more like measuring the width of a single hydrogen atom from the same distance. Another comparison involves the size of the two missions' datasets. When the Hipparcos team printed out its complete catalog, Perryman recalls, it comprised five thick volumes—almost enough to fill a single shelf of a bookcase. Printing out the full Gaia catalog with the same density of information per page, he says, would require about 10 kilometers of shelf space. 'The mind boggles,' he says. 'It's almost incomprehensible; these are numbers and dimensions we're simply not equipped to visualize, so even the analogies are very difficult to grasp.' The best example of the heights such precision can reach may be Gaia's tour de force determination of the solar system's acceleration with respect to a vast, sky-encompassing field of quasars. Quasars are the conspicuously bright cores of remote galaxies that harbor actively feeding supermassive black holes. As such, quasars are among the most powerful beacons astronomers can use to probe distant regions of the universe. Gaia pinpointed the positions of more than one and a half million of them to establish a fixed backdrop of sorts, against which various minuscule motions of our solar system or other nearby celestial objects could be seen. One motion Gaia managed to measure was an astonishingly small acceleration of just 0.232 nanometer per second squared—a continuous atom-scale deflection in the solar system's 220-kilometer-per-second trajectory through the Milky Way, attributed to the gravitational pull from our galaxy's center some 26,000 light-years away. Writ large, the displacement adds up to less than a meter per day—and essentially reflects the real-time sculpting of our galactic orbit as the solar system carves a path through the Milky Way's gravitational field. 'It's an almost circular motion around the galactic center, and it's directed toward the supermassive black hole there,' says astronomer Sergei Klioner of Germany's Dresden University of Technology, who led much of the work behind the measurement. 'No other observational data could come anywhere close to competing with Gaia here.... You often hear the term 'astronomical' in the sense of something being very large—but this is an example where Gaia has shown us something that's astronomically small.' Now that Gaia has gone dark, there's already talk of what comes next. 'Do we really need another astrometry mission?' asks Brown, who first began working on Gaia in 1997. 'Well, not immediately, but the extremely precise stellar reference frame it gave us—upon which many other observatories depend—will eventually deteriorate because all the stars are moving, right?' ESA is envisioning a follow-on mission, which would potential launching in the 2040s. This time that mission would be optimized for infrared observations to allow astronomers to see through the dust that otherwise clouds their view of the Milky Way's star-packed disk and galactic center. 'It's, in a way, wonderful but also a bit sad that people take Gaia for granted because, my God, it was a tough mission,' Perryman reflects. 'I don't feel sadness that it's gone; I'm just delighted and relieved it lasted so long, and I'm very conscious of how remarkable it is that we live in a time when society is willing to pool its resources to support such things, and we have the technology in place to do them. I hope this period continues—but I worry we've been taking that for granted, too.'
Fast Company
14-06-2025
- Science
- Fast Company
How a planetarium show discovered a spiral at the edge of our solar system
If you've ever flown through outer space, at least while watching a documentary or a science fiction film, you've seen how artists turn astronomical findings into stunning visuals. But in the process of visualizing data for their latest planetarium show, a production team at New York's American Museum of Natural History made a surprising discovery of their own: a trillion-and-a-half mile long spiral of material drifting along the edge of our solar system. 'So this is a really fun thing that happened,' says Jackie Faherty, the museum's senior scientist. Last winter, Faherty and her colleagues were beneath the dome of the museum's Hayden Planetarium, fine-tuning a scene that featured the Oort cloud, the big, thick bubble surrounding our Sun and planets that's filled with ice and rock and other remnants from the solar system's infancy. The Oort cloud begins far beyond Neptune, around one and a half light years from the Sun. It has never been directly observed; its existence is inferred from the behavior of long-period comets entering the inner solar system. The cloud is so expansive that the Voyager spacecraft, our most distant probes, would need another 250 years just to reach its inner boundary; to reach the other side, they would need about 30,000 years. The 30-minute show, Encounters in the Milky Way,
