Latest news with #WillGrundy
Yahoo
16-07-2025
- Science
- Yahoo
The best window to see Pluto all year is closing
Think you can spot Pluto? On July 25, the famously elusive dwarf planet reaches opposition—its best and brightest moment of the year. That makes now the ideal time to try to catch a glimpse of it from your own backyard. But be warned: Even at its brightest, Pluto is still a barely-there speck, even through a telescope. But for those willing to search, it's a cosmic scavenger hunt—and a rare chance to see a world nearly four billion miles away. In astronomy, opposition is when a celestial body lies directly opposite the sun from Earth's point of view, placing our planet squarely in the middle. That alignment means the object rises as the sun sets and stays visible all night, making it the best time to observe it. (See National Geographic's first map of Pluto.) What makes opposition so useful for stargazing is a phenomenon known as the opposition effect. 'Things tend to get brighter when they're lit at a smaller phase angle, which is the angle between the sun's rays and the target and the observer. That shrinks to close to zero at opposition,' says Will Grundy, a planetary scientist at Lowell Observatory in Flagstaff, Arizona, where Pluto was discovered. You can see this principle in action on Earth. When the sun is low in the sky, objects create long shadows. But when the sun is directly overhead, those shadows get much smaller, and sometimes they even disappear entirely. At opposition, Pluto's terrain has the fewest shadows, making the dwarf planet appear brighter to us. Because Pluto is so dim, you need a telescope to see it. 'A backyard telescope could do it under the right conditions,' says Grundy. Or you could visit a local observatory and use one of their publicly accessible telescopes. Lowell Observatory, for instance, has a suite of instruments on-site that the public can use six nights per week. But even with a telescope, the sky must be extremely dark to see Pluto. Light pollution, whether from artificial lights or the moon, will easily wash out the dwarf planet. (Did Pluto ever actually stop being a planet? Experts debate.) To find Pluto in dark enough skies, consult a star chart to determine its approximate location. 'It'll just look like one of many faint stars,' says Grundy. But Pluto moves slowly. 'It moves at about three arcseconds per hour, so you won't see it move unless you're willing to wait multiple hours,' says Grundy. You don't have to catch Pluto on July 25 exactly. Because it's so distant—about 3.7 billion miles from the sun—it remains near peak brightness for several days before and after opposition. 'It's a challenge, so it's kind of cool to be able to see Pluto,' says Grundy. Pluto's origin story begins with two other planets. After Uranus was discovered in 1781, astronomers realized that an undiscovered planet might be perturbing Uranus' orbit. 'Sure enough, Neptune was discovered basically bang-on where astronomers predicted it should be,' says Grady. But Percival Lowell, the founder of Lowell Observatory, believed there to be another planet affecting Uranus' orbit: a mysterious 'Planet X.' After a decade of searching, Lowell died in 1916 without finding it. (Discover seven other night sky events to see in July.) Eventually, the search resumed at Lowell Observatory, culminating in Clyde Tombaugh's discovery of Pluto in 1930. As it turns out, Pluto wasn't the gravitational culprit Lowell had imagined. It was far too small to tug on Uranus's orbit in any meaningful way. But it was still a monumental discovery: the solar system's ninth planet—at least until its reclassification as a dwarf planet in 2006. To find Pluto, Tombaugh diligently photographed the night sky, then used a machine to compare two photographic plates, looking for any tiny pinpricks that moved. That's essentially the same method Grundy suggests stargazers use in July to ensure they're looking at Pluto. Following its discovery, Pluto remained just a faint dot until the 1990s, when the Hubble Space Telescope provided some grainy images showing light and dark spots. But it wasn't until 2015 that we got a close-up look at Pluto, thanks to a flyby by NASA's New Horizons spacecraft. The images showed a dynamic, geologically active planet with icy mountains, nitrogen glaciers, and even hints of a subsurface ocean. 'It could be inhabitable if there's liquid water and lots of organic materials and rocks for minerals,' says Grundy, who serves as a co-investigator on the New Horizons mission. That revelation has major implications for astrobiology. 'Pluto moved the goalpost of where inhabitable planetary settings are—much, much farther away from the sun than we ever thought possible,' says Grundy. 'And the same thing will be true around other stars, too. Basically, the inhabitable zone just expanded hugely.'
National Geographic
16-07-2025
- Science
- National Geographic
The best window to see Pluto all year is closing
Pluto's thin, blue haze glows in this image from NASA's New Horizons spacecraft. Though the dwarf planet is just a faint speck through a telescope, opposition this month offers skywatchers their best chance to spot it from Earth. Composite Photograph by NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute A once-a-year alignment makes the dwarf planet easier to spot—if you know where to look. Think you can spot Pluto? On July 25, the famously elusive dwarf planet reaches opposition—its best and brightest moment of the year. That makes now the ideal time to try to catch a glimpse of it from your own backyard. But be warned: Even at its brightest, Pluto is still a barely-there speck, even through a telescope. But for those willing to search, it's a cosmic scavenger hunt—and a rare chance to see a world nearly four billion miles away. What is opposition—and why is it the best time to see Pluto? In astronomy, opposition is when a celestial body lies directly opposite the sun from Earth's point of view, placing our planet squarely in the middle. That alignment means the object rises as the sun sets and stays visible all night, making it the best time to observe it. (See National Geographic's first map of Pluto.) What makes opposition so useful for stargazing is a phenomenon known as the opposition effect. 'Things tend to get brighter when they're lit at a smaller phase angle, which is the angle between the sun's rays and the target and the observer. That shrinks to close to zero at opposition,' says Will Grundy, a planetary scientist at Lowell Observatory in Flagstaff, Arizona, where Pluto was discovered. You can see this principle in action on Earth. When the sun is low in the sky, objects create long shadows. But when the sun is directly overhead, those shadows get much smaller, and sometimes they even disappear entirely. At opposition, Pluto's terrain has the fewest shadows, making the dwarf planet appear brighter to us. Pluto and its moon Charon perform a cosmic dance in this 2015 color movie from NASA's New Horizons mission. Animation by NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute Pluto nearly fills the frame in this image from NASA's New Horizons spacecraft, taken just before its closest approach in 2015. Photograph by NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute Because Pluto is so dim, you need a telescope to see it. 'A backyard telescope could do it under the right conditions,' says Grundy. Or you could visit a local observatory and use one of their publicly accessible telescopes. Lowell Observatory, for instance, has a suite of instruments on-site that the public can use six nights per week. But even with a telescope, the sky must be extremely dark to see Pluto. Light pollution, whether from artificial lights or the moon, will easily wash out the dwarf planet. (Did Pluto ever actually stop being a planet? Experts debate.) To find Pluto in dark enough skies, consult a star chart to determine its approximate location. 'It'll just look like one of many faint stars,' says Grundy. But Pluto moves slowly. 'It moves at about three arcseconds per hour, so you won't see it move unless you're willing to wait multiple hours,' says Grundy. You don't have to catch Pluto on July 25 exactly. Because it's so distant—about 3.7 billion miles from the sun—it remains near peak brightness for several days before and after opposition. 'It's a challenge, so it's kind of cool to be able to see Pluto,' says Grundy. These photographic plates helped astronomer Clyde Tombaugh discover Pluto in 1930. By comparing nearly identical images of the night sky with a device called a blink comparator, he found a tiny object (marked by arrows) outside the orbit of Neptune, which was named Pluto. Photograph by Detlev Van Ravenswaay, Science Photo Library Pluto's origin story begins with two other planets. After Uranus was discovered in 1781, astronomers realized that an undiscovered planet might be perturbing Uranus' orbit. 'Sure enough, Neptune was discovered basically bang-on where astronomers predicted it should be,' says Grady. But Percival Lowell, the founder of Lowell Observatory, believed there to be another planet affecting Uranus' orbit: a mysterious 'Planet X.' After a decade of searching, Lowell died in 1916 without finding it. (Discover seven other night sky events to see in July.) Eventually, the search resumed at Lowell Observatory, culminating in Clyde Tombaugh's discovery of Pluto in 1930. As it turns out, Pluto wasn't the gravitational culprit Lowell had imagined. It was far too small to tug on Uranus's orbit in any meaningful way. But it was still a monumental discovery: the solar system's ninth planet—at least until its reclassification as a dwarf planet in 2006. To find Pluto, Tombaugh diligently photographed the night sky, then used a machine to compare two photographic plates, looking for any tiny pinpricks that moved. That's essentially the same method Grundy suggests stargazers use in July to ensure they're looking at Pluto. Following its discovery, Pluto remained just a faint dot until the 1990s, when the Hubble Space Telescope provided some grainy images showing light and dark spots. But it wasn't until 2015 that we got a close-up look at Pluto, thanks to a flyby by NASA's New Horizons spacecraft. The images showed a dynamic, geologically active planet with icy mountains, nitrogen glaciers, and even hints of a subsurface ocean. 'It could be inhabitable if there's liquid water and lots of organic materials and rocks for minerals,' says Grundy, who serves as a co-investigator on the New Horizons mission. That revelation has major implications for astrobiology. 'Pluto moved the goalpost of where inhabitable planetary settings are—much, much farther away from the sun than we ever thought possible,' says Grundy. 'And the same thing will be true around other stars, too. Basically, the inhabitable zone just expanded hugely.'
Yahoo
15-06-2025
- Science
- Yahoo
Pluto's hazy skies are making the dwarf planet even colder, James Webb Space Telescope finds
When you buy through links on our articles, Future and its syndication partners may earn a commission. The James Webb Space Telescope (JWST) has discovered that a hazy sky over frozen Pluto is helping to cool the dwarf planet's atmosphere, while at the same time giving methane and other organic molecules a kick out of Pluto's atmosphere, where some are subsequently being gathered up by Pluto's close companion, Charon. The discovery of the haze was predicted back in 2017 by planetary scientist Xi Zhang of the University of California, Santa Cruz, to explain why Pluto's thin atmosphere is so leaky. Based on measurements from NASA's New Horizons spacecraft, which hurtled past Pluto and Charon in 2015, planetary scientist Will Grundy at the Lowell Observatory in Arizona calculated that Pluto's atmosphere is losing 1.3 kilograms (2.9 pounds) of methane to space every second, and about 2.5% of this methane is being intercepted by Charon, staining its poles red with organic chemistry. Nowhere else in the solar system do we see an atmosphere leaking onto a neighboring body. The cause of this atmospheric escape was unknown, but Zhang reasoned that if Pluto's atmosphere contained a layer of haze, then this haze would absorb what little extreme ultraviolet light from the distant sun reaches Pluto, providing the energy to give molecules the nudge they need to escape into space. Besides the haze heating the atmospheric molecules so that they can escape, Zhang also realized that the haze could have a cooling effect on Pluto's atmosphere — an effect that had previously been detected in Pluto's mesosphere, which is the third layer of the atmosphere above the virtually non-existent troposphere and the denser stratosphere. Pluto's mesosphere is found between 20 kilometers and 40 kilometers (12.4 to 24.9 miles) high and reaches a maximum temperature of minus 163 degrees Celsius (110 Kelvin/minus 262 degrees Fahrenheit) before cooling at a rate of 0.2 degrees Celsius per kilometer, to a minimum of minus 203 degrees C (70 Kelvin/minus 334 degrees F). The problem was that, until now, no haze had been detected on Pluto. Then along came the JWST. Zhang had predicted that any atmospheric cooling spurred on by a layer of haze would result in thermal emission at mid-infrared wavelengths. Mid-infrared emission had been detected coming from the Pluto-Charon system before, going all the way back to Europe's Infrared Space Observatory in 1997, NASA's Spitzer Space Telescope in 2004, and Europe's Herschel Space Observatory in 2012. However, on each occasion, the telescope lacked the resolution to distinguish between Pluto and Charon and determine where the emission was coming from. But JWST, with its 6.5-meter (21.4 feet) primary mirror and Mid-Infrared Instrument (MIRI), is able to distinguish between Pluto and Charon. So Zhang, as part of a team led by Tanguy Bertrand of the Observatoire de Paris, was able to use JWST to detect the thermal mid-infrared emission from the long-elusive haze. "We use the term 'haze' to describe layers of solid aerosols suspended high in an atmosphere," Bertrand told "These aerosols scatter light and reduce visibility, forming a diffuse and semi-transparent layer." Pluto's atmosphere is mostly nitrogen, with a smidgen of carbon dioxide and hydrocarbons such as methane, benzene, diacetylene and hydrogen cyanide. This atmosphere is exceptionally thin; the surface pressure is just 13 microbars, in comparison to Earth's surface pressure of about 1 bar. (One bar is equivalent to one million microbars.) And because of Pluto's low gravity, the upper atmosphere extends quite a long way from the surface, by several Pluto radii (the radius of Pluto is 1,188.3 kilometers, or 737 miles). All molecules need is a slight nudge to send them spinning out of the atmosphere, and the energy to give them that nudge comes from the sun. "A significant fraction of the incoming solar extreme ultraviolet radiation is absorbed by the upper atmosphere, leading to heating that powers atmospheric mass loss," said Bertrand. "Atmospheric gases such as nitrogen and methane are responsible for absorbing radiation at these wavelengths." But how can the haze alternatively cause both atmospheric heating and cooling? "Cooling or heating depends on the haze properties, such as particle size, shape and composition — i.e., icy with hydrocarbon ice, or non-icy — which are not very well known," said Bertrand. "We are currently investigating this with state-of-the-art microphysical [i.e., on the scale of atoms and molecules] models." The ability of the haze to cool or heat the atmosphere means that it therefore controls the balance of energy in Pluto's atmosphere, affecting global temperatures, atmospheric circulation and what passes for climate on the frigid dwarf planet. This climate system is dominated by cycles of sublimation and freezing out of molecular nitrogen, methane, and carbon monoxide, much of which hails from the deep glacier in Sputnik Planitia, which is the heart-shaped feature on the dwarf planet's surface. RELATED STORIES — How Pluto captured its largest moon Charon with a 10-hour icy 'kiss' — Why is Pluto not a planet? — James Webb Space Telescope deciphers the origins of Pluto's icy moon Charon Zhang described for this energy balance in detail. "Based on New Horizon's temperature observations from 2015, we found that gas heating significantly exceeds gas cooling," he said. "So there is a net radiative heating of the atmosphere. To maintain energy balance under these conditions, the haze must provide the necessary net radiative cooling. But it remains unclear whether haze has a net cooling effect during other seasons, as Pluto's seasons vary dramatically!" Those "seasons" are so drastically different because of Pluto's elongated orbit, which takes it from closer to the sun than Neptune to almost twice as far out. Even out here, in the depths of the solar system, this difference in distance markedly affects the amount of heating Pluto receives. Pluto's haze is similar to the hydrocarbon-rich haze found on Saturn's moon Titan. Both hazes result from the photochemistry of solar extreme ultraviolet light reacting with molecules such as nitrogen and methane. Even the early Earth, prior to the rise of an oxygen-enriched atmosphere over 2.4 billion years ago, may have harbored a haze of hydrocarbons in its atmosphere similar to Pluto, albeit much more dense. Understanding Pluto's atmosphere could therefore potentially teach us something about our own planet's beginnings. The new study was published in the journal Nature Astronomy on June 2
