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comets

  • Comet NEOWISE Approaches Earth

    Tonight could be your best chance to see Comet NEOWISE (C/2020 F3) for the next 6,800 years. On July 23rd, the comet makes its closest approach to Earth--only 0.63 AU (103 million km) away. It's visible to the naked eye from dark sky sites, and an easy target for digital cameras. Here's where to look just below the Big Dipper:

    Urban sky watchers with light pollution might have trouble seeing the comet. If you're one of them, try using binoculars. Even a little magnification brings NEOWISE into view.

    Short exposures with digital cameras reveal the comet's magnificent double tail. Petr Horálek sends this picture from Seč lake in the Czech Republic:

    "I still cannot believe my eyes," says Horálek. "The comet's ion tail is truly long, extending more than 20 degrees into the bowl of the Big Dipper and beyond. When comet gets closest to Earth, the tail should be longest. Now I only hope for clear skies on July 23rd!"

    For reference, Horálek's image is a stack of 11 photos--each one a 30 second exposure at ISO 1250. He used a Canon 6D digital camera with a Sigma 50mm lens (f2.2).

    And if you miss the comet... no worries. It'll be back in 6,800 years. Sky maps: July 22, 23, 24.

  • Comet NEOWISE bids farewell to Earth

    COMET NEOWISE is bidding farewell to Earth, not to be seen again for almost 7,000 years - but one astrophotographer has detailed the comet's passing in stunning detail.

    Comet NEOWISE has been mesmerising stargazers across the northern hemisphere as the giant ball of ice produces a stunning gaseous tail visible to Earth. The comet is now barely visible as it moves away from our planet, but one astrophotographer has provided a handy reminder of the comet's visit.

    Photographer Dennis Mammana of Borrego Springs, California, created a stunning time-lapse photo of the comet's visit, with an image of NEOWISE on July 18, through to the peak on July 23 to now - where the comet is barely visible - all merged into one photograph.

    Mr Mammana said: "I hope everyone got to see Comet NEOWISE during its recent visit.

    "It became bright enough to see easily with the unaided eye from dark rural locations but now, unfortunately, has faded into the realm of large binoculars and telescopes.

    "I photographed it each night from July 18th to 27th. In this sequence you can see the comet changing its size and brightness as it first approaches Earth and then recedes back into the depths of our solar system, not to return to our neighborhood for nearly 68 centuries."

    Some scientists have warned Comet NEOWISE could be the last comet which could be visible to the naked eye.

    Light pollution is increasingly making it difficult for astronomers and amateur stargazers alike, as artificial lighting is constantly on the increase, a team of researchers say.

    According to the Natural History museum, light pollution caused by artificial lighting is increasing by an average of six percent a year.

    And as things get lighter here on Earth, the sky at night seemingly gets darker.

    Gareth Dorrian, postdoctoral research fellow in Space Science at the University of Birmingham, and Ian Whittaker, senior lecturer in physics from Nottingham Trent University, said everyone should have taken advantage of the comet, the first to be visible from Earth since the 90s, as it could be our last.

    The pair wrote in The Conversation: "So comet NEOWISE will only be seen for a few weeks near-Earth while it is near perihelion (its closest approach to the Sun).

    "It will then spend thousands of years moving slowly near the other end of its orbit.

    "It’s aphelion (farthest point) is estimated at 630 astronomical units (AU), with one AU being the distance between the Earth and the Sun.

    "With the constant increase of light pollution in the night sky the observation of comets with the naked eye is becoming much rarer.

    "For now, though, NEOWISE presents a fantastic opportunity for millions of people to see a night sky phenomenon which typically only presents itself perhaps once in a decade or more. Enjoy the view!"

  • Comet NEOWISE Graces the Morning Sky

    BRIGHT MORNING COMET:Comet NEOWISE (C/2020 F3) is doing something very rare: Shining through the rosy glow of dawn. "How many times in your life can you say 'I saw a comet at dawn'--and really mean it?" asks Petr Horálek of the Czech Republic. "It happened to me this morning!" Horálek took this picture just before sunrise over Proseč u Chrudimi:

    "Pretty clear skies allowed me to capture Comet NEOWISE from the ephemeral moment of its rising to the moment I was able to see it with naked eyes--even if still very hardly--on July 4th July," says Horálek.

    Yesterday, July 3rd, Comet NEOWISE passed by the sun near the orbit of Mercury. Intense solar heating boosted its brightness to magnitude +1 (now +2), allowing it to be seen despite its close proximity to the sun. This development has turned NEOWISE into one of the most remarkable comets in years.

    In Stixendorf, Austria, Comet NEOWISE was visible from the very moment it peeked above dark clouds hugging the eastern horizon. Astrophotographer Michael Jaeger recorded this video:

    A tracked exposure by Jaeger shows the extent of the comet's magnificent fan-shaped tail:

    Comet NEOWISE is just getting started. It is barely visible to the naked eye now only because it has to compete with the glow of dawn. The situation will improve in the days ahead as NEOWISE moves into darker skies. If it retains its current luminosity, the comet should put on a very good show indeed. Set your alarm for dawn! Sky maps: July 4, 5, 6.

  • Comet NEOWISE has grown, now consists of "supersized nucleus" with two tails

    Comet NEOWISE just keeps getting better. Not only is it visible to the naked eye in morning twilight, but also, now, it has two tails. The brighter of the two is the dust tail, made of dusty-rocky grains sprinkled like crumbs along the comet's curved orbit. Just above it is the faint ion tail, made of gas shoved straight away from the sun by the solar wind.

    "The ion tail is relatively dim," says Voltmer. "To record it, I had to stack 63 frames captured with my Nikon D800 digital camera (ISO 320)."

    Look carefully at the ion tail; it's blue. This makes it tricky to see against a backdrop of blue twilight. Visibility will improve in the days ahead as the comet moves into darker skies farther from the sun.

    Stay tuned! Sky maps: July 9, 10, 11, 12, 13, 14, 15.

    COMET NEOWISE HAS A SUPER-SIZED NUCLEUS

    Now we know why Comet NEOWISE (C/2020 F3) is so bright. Its nucleus is huge. Researchers working with NASA's NEOWISE spacecraft have analyzed infrared emissions from the comet's core, shown here in discovery images from March 2020:

    The glow is proportional to the size of the nucleus--the nugget of dust and frozen gas at the heart of the comet. "From its infrared signature, we can tell that [the nucleus] is about 5 kilometers across," says Joseph Masiero, NEOWISE deputy principal investigator at NASA's Jet Propulsion Laboratory.

    "5 km is extremely large for a comet approaching this close to the sun (think Comet McNaught-sized), which explains its high activity," says Qicheng Zhang, a PhD student in planetary sciences at Caltech.

    On July 3rd, Comet NEOWISE passed by the sun near the orbit of Mercury. The oversized nucleus helped it survive the encounter, which some comets would have found too hot to handle. Now NEOWISE's sun-heated core is spewing massive amounts of dust and gas, creating a worldwide sensation.

    "Here is my daughter Izar ('Star' in the Basque language) pointing out the comet in the sunrise sky over Girona, Catalonia, Spain," says photographer Juan Carlos Casado. "It was easy to see with the naked eye."

    © Juan Carlos Casado

    "Foreground lighting in the photo is natural, provided by the Moon," he adds.

    For Comet NEOWISE, the future looks bright. Its large nucleus is a reservoir of dust and gas that should continue to fill the comet's double tail with visible material for weeks to come. Observing tips: Wake up about 90 minutes before sunrise, find a place with a clear horizon, and look northeast. The comet is visible to the naked eye as a fuzzy patch with a tail. Binoculars are recommended for full effect.



    Sky maps: July 9, 10, 11, 12, 13, 14, 15.

  • Comet NEOWISE Visible in the Northwest Sky, and here's how to see it

    We have some great chances to see a new comet this month which won't be back for another 6800 years.

    The comet is named NEOWISE after the NASA mission that discovered it: the Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE). It will be a little easier to see in the northwest sky every night through July 23. To the naked eye, NEOWISE will look like a fuzzy star with a bit of a tail, NASA says. So try to use at least binoculars or a small telescope.

    “From its infrared signature, we can tell that it is about 5 kilometers [3 miles] across, and by combining the infrared data with visible-light images, we can tell that the comet’s nucleus is covered with sooty, dark particles left over from its formation near the birth of our solar system 4.6 billion years ago,” said Joseph Masiero, NEOWISE deputy principal investigator at NASA’s Jet Propulsion Laboratory in Southern California.

    To find NEOWISE, look just below the Big Dipper in the northwest sky. Remember, the time to look is just after sunset. It’s about that simple, but the map below is a good guide. Happy comet hunting!

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