Connect with us

Science

Following Comet Y1 ATLAS: the 'Lost Comet' of Spring – Universe Today

Published

on


Got clear skies? If you’re like us, you’ve been putting the recent pandemic-induced exile to productive use, and got out under the nighttime sky. And though 2020 has yet to offer up a good bright ‘Comet of the Century’ to keep us entertained, there have been a steady stream of good binocular comets for northern hemisphere viewers, including C/2017 T2 PanSTARRS and C/2019 Y4 ATLAS. This week, I’d like to turn your attention to another good binocular comet that is currently at its peak: the ‘other’ comet ATLAS, C/2019 Y1 ATLAS.

Discovered by the Asteroid Terrestrial-Last Alert System (ATLAS) based at two geographically separate sites on Haleakala and Mauna Loa, Hawaii on the night of December 16th, 2019, Y1 ATLAS was one of the final comet discoveries of 2019.

The comet is on a 3,500 year path around the Sun on a prograde orbit inclined 73 degrees relative to the ecliptic. When this comet last came through the inner solar system around the 25th century BC, the Great Cheops Pyramid of Giza was still fresh from the builders.

Unfortunately, cosmic bad luck sees Comet Y1 ATLAS visiting us at almost exactly the wrong time of year. Had Y1 Atlas crossed the ecliptic in October, it would have passed just 0.08 Astronomical Units (AU) or 7.4 million miles (12 million miles) from the Earth just exterior to our orbit, and would have put on a fine show. As is often the case with comets, six months earlier or later would’ve made a big difference.

The orbital path of Comet Y1 ATLAS through the inner solar system. Credit: NASA/JPL.

As it stands, Comet Y1 ATLAS just passed perihelion at 0.861 AU (80 million miles/130 million kilometers) from the Sun on March 16th, and currently shines at magnitude +8 in the constellation of Andromeda. March through mid-April sees the comet holding steady about 10 degrees above the northwestern horizon at dusk for mid-northern latitude observers, until it vaults northward towards the north celestial pole, becoming a circumpolar object from late April through May. The comet follows the zero hour line in right ascension right through the end of Spring.

As of writing this, this apparition of the comet seems to be slightly over-performing by about half to a full magnitude or so.

Comet Y1 ATLAS from shortly after discovery on December 20th. Credit: Remanzacco Observatory.

Let’s hope that this trend holds. There is also something else that’s very special about comet Y4 ATLAS: it’s similar orbit suggests that it is a fragment of C/1988 A1 Liller. This may have been the result of a cometary breakup long ago, as C/1996 Q1 Tabur and C/2015 F3 Swan all seem to belong to the same family of objects. This also suggests that Y1 ATLAS is dynamically new, and could produce an outburst of its own.

Here’s the blow-by-blow of celestial dates with destiny for comet Y1 ATLAS in the Spring of 2020:

(note: unless otherwise mentioned, “passes near” in the following text means less than one degree).

Path of the comet through late May across the sky. Credit: Starry Night.

March

27-Photo op: the comet passes between NGC 7662 (the Blue Snowball planetary nebula, at 9 degrees distant), and M31 (the Andromeda Galaxy) at 5 degrees away.

The path of Comet Y1 ATLAS through late April at dusk as seen from latitude 35 degrees north. Credit Starry Night.

April

1-Crosses into the
constellation of Cassiopeia the Queen.

14-Crosses the
galactic equator northward.

26-Crosses into the constellation Cepheus the King.

The projected light-curve of Comet C/2019 Y1 ATLAS. Credit: Seiichi Yoshida’s Weekly Information About Bright Comets.

May

1-Photo-op: Y1 ATLAS groups with two other notable 2020 comets: T2 PanSTARRS (6 degrees distant) and Y4 ATLAS (20 degrees distant).

2-Crosses into Camelopardalis, and passes closest to the North Celestial Pole (NCP) at less than eight degrees.

3-Closest to the Earth at 1.17 AU distant.

9-Crosses into Draco.

13- Crosses into
Ursa Major, and passes 3 degrees from M81/M82.

20-Passes near Duhbe
(Alpha Ursae Majoris).

24-passes Owl Nebula Messier 97.

June

22-Passes into Coma Berenices.

29-Passes near the open cluster Melotte 111.

A negative exposure of Comet Y1 ATLAS from March 23rd. Image credit and copyright: Michael Jäger.

As we enter into July, Comet Y1 ATLAS should drop back below binocular visibility to the sub +10th magnitude range, not to visit the inner solar system again until sometime in the mid-7th millennium AD.

Observing comets with binoculars is as simple as sweeping the suspect field and looking for the fuzzy little ‘star’ that stubbornly refuses to snap into focus. Keep in mind, an +8th magnitude comet can appear visually fainter than an +8th magnitude star, as all those precious photons are ‘smeared’ out over the comet’s apparent surface area.

Comet Y4 ATLAS from March 20th. Image credit and copyright: Michael Jäger.

Also, we’ve been getting lots of queries on Comet C/2019 Y4 ATLAS as of late. Yes, there is mounting excitement as this over-performing comet heads towards perihelion in late May… already, the dusty coma of the comet is an amazing 720,000 kilometers (450,000 miles) across… and that’s while it’s still 1.6 AU from the Sun. Claims, however, that it will become “the brightest comet ever witnessed!” need to be met with extreme skepticism. Yes, it may reach 0 magnitude near perihelion on May 31st… but it will also appear 13 degrees from the Sun on that date, and get swamped in the Sun’s glare. The best bet is to nab the comet near dawn in early May, before it disappears from view for good.

Hopefully, tracking down these comets will pass the time in exile. We could really use a solar outburst, galactic supernovae courtesy of Betelgeuse, or great naked eye comet right about now… just nothing apocalyptic.

-Lead image of Comet C/2019 Y1 ATLAS courtesy of José J. Chambó/Slooh

Let’s block ads! (Why?)



Source link

Continue Reading

Science

NASA Scientists Find Secret in Decades-Old Voyager 2 Data About the Ice Giant Uranus – SciTechDaily

Published

on


Voyager 2 took this image as it approached the planet Uranus on January 14, 1986. The planet’s hazy bluish color is due to the methane in its atmosphere, which absorbs red wavelengths of light. Credit: NASA/JPL-Caltech

The ice giant Uranus appears to be losing a bit of its atmosphere to space, perhaps siphoned away by the planet’s magnetic field.

Eight and a half years into its grand tour of the solar system, NASA’s Voyager 2 spacecraft was ready for another encounter. It was January 24, 1986, and soon it would meet the mysterious seventh planet, icy-cold Uranus.

Over the next few hours, Voyager 2 flew within 50,600 miles (81,433 kilometers) of Uranus’ cloud tops, collecting data that revealed two new rings, 11 new moons and temperatures below minus 353 degrees Fahrenheit (minus 214 degrees Celsius). The dataset is still the only up-close measurements we have ever made of the planet.

Three decades later, scientists reinspecting that data found one more secret.

Unbeknownst to the entire space physics community, 34 years ago Voyager 2 flew through a plasmoid, a giant magnetic bubble that may have been whisking Uranus’ atmosphere out to space. The finding, reported in Geophysical Research Letters, raises new questions about the planet’s one-of-a-kind magnetic environment.

A Wobbly Magnetic Oddball

Planetary atmospheres all over the solar system are leaking into space. Hydrogen springs from Venus to join the solar wind, the continuous stream of particles escaping the Sun. Jupiter and Saturn eject globs of their electrically-charged air. Even Earth’s atmosphere leaks. (Don’t worry, it will stick around for another billion years or so.)

The effects are tiny on human timescales, but given long enough, atmospheric escape can fundamentally alter a planet’s fate. For a case in point, look at Mars.

“Mars used to be a wet planet with a thick atmosphere,” said Gina DiBraccio, space physicist at NASA’s Goddard Space Flight Center and project scientist for the Mars Atmosphere and Volatile Evolution, or MAVEN mission. “It evolved over time” — 4 billion years of leakage to space — “to become the dry planet we see today.”

Uranus Magnetic Field

More Secret
An animated GIF showing Uranus’ magnetic field. The yellow arrow points to the Sun, the light blue arrow marks Uranus’ magnetic axis, and the dark blue arrow marks Uranus’ rotation axis. Credit: NASA/Scientific Visualization Studio/Tom Bridgman

Atmospheric escape is driven by a planet’s magnetic field, which can both help and hinder the process. Scientists believe magnetic fields can protect a planet, fending off the atmosphere-stripping blasts of the solar wind. But they can also create opportunities for escape, like the giant globs cut loose from Saturn and Jupiter when magnetic field lines become tangled. Either way, to understand how atmospheres change, scientists pay close attention to magnetism.

That’s one more reason Uranus is such a mystery. Voyager 2’s 1986 flyby revealed just how magnetically weird the planet is.

“The structure, the way that it moves … ,” DiBraccio said, “Uranus is really on its own.”

Unlike any other planet in our solar system, Uranus spins almost perfectly on its side — like a pig on a spit roast — completing a barrel roll once every 17 hours. Its magnetic field axis points 60 degrees away from that spin axis, so as the planet spins, its magnetosphere — the space carved out by its magnetic field — wobbles like a poorly thrown football. Scientists still don’t know how to model it.

This oddity drew DiBraccio and her coauthor Dan Gershman, a fellow Goddard space physicist, to the project. Both were part of a team working out plans for a new mission to the “ice giants” Uranus and Neptune, and they were looking for mysteries to solve.

Uranus’ strange magnetic field, last measured more than 30 years ago, seemed like a good place to start.

So they downloaded Voyager 2’s magnetometer readings, which monitored the strength and direction of the magnetic fields near Uranus as the spacecraft flew by. With no idea what they’d find, they zoomed in closer than previous studies, plotting a new datapoint every 1.92 seconds. Smooth lines gave way to jagged spikes and dips. And that’s when they saw it: a tiny zigzag with a big story.

“Do you think that could be … a plasmoid?” Gershman asked DiBraccio, catching sight of the squiggle.

Little known at the time of Voyager 2’s flyby, plasmoids have since become recognized as an important way planets lose mass. These giant bubbles of plasma, or electrified gas, pinch off from the end of a planet’s magnetotail — the part of its magnetic field blown back by the Sun like a windsock. With enough time, escaping plasmoids can drain the ions from a planet’s atmosphere, fundamentally changing its composition.

They had been observed at Earth and other planets, but no one had detected plasmoids at Uranus — yet.

DiBraccio ran the data through her processing pipeline, and the results came back clean. “I think it definitely is,” she said.

The Bubble Escapes

The plasmoid DiBraccio and Gershman found occupied a mere 60 seconds of Voyager 2’s 45-hour-long flight by Uranus. It appeared as a quick up-down blip in the magnetometer data. “But if you plotted it in 3D, it would look like a cylinder,” Gershman said.

Comparing their results to plasmoids observed at Jupiter, Saturn and Mercury, they estimated a cylindrical shape at least 127,000 miles (204,000 kilometers) long, and up to roughly 250,000 miles (400,000 kilometers) across. Like all planetary plasmoids, it was full of charged particles — mostly ionized hydrogen, the authors believe.?

Readings from inside the plasmoid — as Voyager 2 flew through it — hinted at its origins. Whereas some plasmoids have a twisted internal magnetic field, DiBraccio and Gershman observed smooth, closed magnetic loops. Such loop-like plasmoids are typically formed as a spinning planet flings bits of its atmosphere to space. “Centrifugal forces take over, and the plasmoid pinches off,” Gershman said. According to their estimates, plasmoids like that one could account for between 15% and 55% of atmospheric mass loss at Uranus, a greater proportion than either Jupiter or Saturn. It may well be the dominant way Uranus sheds its atmosphere to space.

How has plasmoid escape changed Uranus over time? With only one set of observations, it’s hard to say.

“Imagine if one spacecraft just flew through this room and tried to characterize the entire Earth,” DiBraccio said. “Obviously it’s not going to show you anything about what the Sahara or Antarctica is like.”

But the findings help focus new questions about the planet. The remaining mystery is part of the draw. “It’s why I love planetary science,” DiBraccio said. “You’re always going somewhere you don’t really know.”

Reference: “Voyager 2 constraints on plasmoid‐based transport at Uranus” by Gina A. DiBraccio and Daniel J. Gershman, 9 August 2019, Geophysical Research Letters.
DOI: 10.1029/2019GL083909

The twin Voyager spacecraft were built by and continue to be operated by NASA’s Jet Propulsion Laboratory. JPL is a division of Caltech in Pasadena. The Voyager missions are a part of the NASA Heliophysics System Observatory, sponsored by the Heliophysics Division of the Science Mission Directorate in Washington.

Let’s block ads! (Why?)



Source link

Continue Reading

Science

Uranus is losing its atmosphere because of its weird wobbly magnetic field – Yahoo Tech

Published

on



<p class="canvas-atom canvas-text Mb(1.0em) Mb(0)–sm Mt(0.8em)–sm" type="text" content="Voyager 2 may have long ago left our solar system and headed out into interstellar space to explore the unknown, but scientists are still learning from the data it collected as it passed by the other planets in our system. A new analysis of 30-year-old data has revealed a surprising finding about the planet Uranus — the huge magnetic bubble surrounding it is siphoning its atmosphere off into space.” data-reactid=”12″>Voyager 2 may have long ago left our solar system and headed out into interstellar space to explore the unknown, but scientists are still learning from the data it collected as it passed by the other planets in our system. A new analysis of 30-year-old data has revealed a surprising finding about the planet Uranus — the huge magnetic bubble surrounding it is siphoning its atmosphere off into space.

<p class="canvas-atom canvas-text Mb(1.0em) Mb(0)–sm Mt(0.8em)–sm" type="text" content="Atmospheres being lost into space can have a profound effect on the development of a planet. As an example, Mars is thought to have started out as an ocean-covered planet similar to Earth but lost its atmosphere over time. “Mars used to be a wet planet with a thick atmosphere,” Gina DiBraccio, space physicist at NASA’s Goddard Space Flight Center and project scientist for the Mars Atmosphere and Volatile Evolution, or MAVEN mission, said in a statement. “It evolved over time to become the dry planet we see today.”” data-reactid=”13″>Atmospheres being lost into space can have a profound effect on the development of a planet. As an example, Mars is thought to have started out as an ocean-covered planet similar to Earth but lost its atmosphere over time. “Mars used to be a wet planet with a thick atmosphere,” Gina DiBraccio, space physicist at NASA’s Goddard Space Flight Center and project scientist for the Mars Atmosphere and Volatile Evolution, or MAVEN mission, said in a statement. “It evolved over time to become the dry planet we see today.”

Uranus’s atmospheric loss is driven by its strange magnetic field, the axis of which points at an angle compared to the axis on which the planet spins. That means its magnetosphere wobbles as it moves, which makes it very difficult to model. “The structure, the way that it moves,” DiBraccio said, “Uranus is really on its own.”

Voyager 2 took this image as it approached the planet Uranus on Jan. 14, 1986. The planet's hazy bluish color is due to the methane in its atmosphere, which absorbs red wavelengths of light.
<figcaption class="C($c-fuji-grey-h) Fz(13px) Py(5px) Lh(1.5)" title="Voyager 2 took this image as it approached the planet Uranus on Jan. 14, 1986. The planet’s hazy bluish color is due to the methane in its atmosphere, which absorbs red wavelengths of light. NASA/JPL-Caltech” data-reactid=”22″>

Voyager 2 took this image as it approached the planet Uranus on Jan. 14, 1986. The planet’s hazy bluish color is due to the methane in its atmosphere, which absorbs red wavelengths of light. NASA/JPL-Caltech

Due to the wobbling of the magnetosphere, bits of the atmosphere are drained away in what are called plasmoids — bubbles of plasma which pinch off from the magnetic field as it is blown around by the Sun. Although these plasmoids have been seen on Earth and on some other planets, they had never been observed on Uranus before the recent analysis of old Voyager 2 data.

“Imagine if one spacecraft just flew through this room and tried to characterize the entire Earth,” DiBraccio said. “Obviously it’s not going to show you anything about what the Sahara or Antarctica is like.”

“It’s why I love planetary science,” DiBraccio said. “You’re always going somewhere you don’t really know.”

<p class="canvas-atom canvas-text Mb(1.0em) Mb(0)–sm Mt(0.8em)–sm" type="text" content="The research is published in the journal Geophysical Research Letters.” data-reactid=”29″>The research is published in the journal Geophysical Research Letters.

Let’s block ads! (Why?)



Source link

Continue Reading

Science

Sunlit Peaks in the Himalayas – NASA

Published

on


As the International Space Station (ISS) was traveling over India towards the day-night terminator, an astronaut shot this photograph of Earth’s third-highest summit, Kangchenjunga, and its surrounding peaks warmly lit by the setting Sun. With the Sun low in the sky, the light was passing through more atmosphere, which scatters it towards the red end of the visible spectrum.

Kangchenjunga rises more than 8500 meters (28,000 feet) above sea level. It stands on the border of Nepal and India about 120 kilometers (75 miles) east-southeast of Mount Everest. The apex of Kangchenjunga is surrounded by valley glaciers, some of which (like Yalung) are discernable in the shadows of this image. Just out of reach of the Sun’s rays, a deck of low-lying clouds lingers over the valley floors.

Thirteen other mountain peaks on Earth rise higher than 8000 meters (26,000 feet). These are known by mountaineers and climbers as the “eight-thousanders.” Oblique views such as this one give the dauntingly dangerous terrain a three-dimensional appearance and depth.

Astronaut photograph ISS061-E-92131 was acquired on December 16, 2019, with a Nikon D5 digital camera using a 500 millimeter lens and is provided by the ISS Crew Earth Observations Facility and the Earth Science and Remote Sensing Unit, Johnson Space Center. The image was taken by a member of the Expedition 61 crew. The image has been cropped and enhanced to improve contrast, and lens artifacts have been removed. The International Space Station Program supports the laboratory as part of the ISS National Lab to help astronauts take pictures of Earth that will be of the greatest value to scientists and the public, and to make those images freely available on the Internet. Additional images taken by astronauts and cosmonauts can be viewed at the NASA/JSC Gateway to Astronaut Photography of Earth. Caption by Andrew Britton, Jacobs, JETS Contract at NASA-JSC.

Let’s block ads! (Why?)



Source link

Continue Reading

Trending