Comet Leonard on course for a good showing – Astronomy Now

Comet 2021 A1 (Leonard) shot from New Mexico, USA, before dawn on 17 November. The comet is located in southern Canes Venatici, close to the spiral galaxy NGC 4395. Image: Rolando Ligustri.

Comet 2021 A1 (LEONARD) has now broken out of the cometary pack to brighten up and shine close to naked-eye magnitude (+7.2) at the time of writing (27 November). All the indications look good for it at the very least to become marginally visible to the naked-eye and a nice object through a pair of binoculars at some time while its accessible from UK skies during the first ten days or so December. Throughout this period of time comet 2021 A1 (LEONARD) is a morning object seen rocketing through southern Canes Venatici, Boötes, Serpens Caput and Ophiuchus, steadily accelerating as it zero’s in on a close approach to Earth on 12 December.

Comet 2021 A1 (Leonard) was the first comet discovery of 2021 (hence the 2021 A1 designation), on 3 January 2021 by Greg Leonard from Arizona’s Mount Lemmon Observatory. By quirky chance, this is exactly a year before its perihelion passage on 3 January 2022! At perihelion, comet 2021 A1 (Leonard) will lie around 92.7 million kilometres (0.61 AU) from the Sun. It was discovered out in Jupiter’s domain (~5 AU away) as a tiny smudge of light with an apparent diameter of around 10” and shining at nineteenth-magnitude. Astronomers quickly calculated that the comet will be ejected from the Solar System at some point after perihelion passage.

Comet 2021 A1 (LEONARD) comes closest to Earth on 12 December, when it will lie around 34.4 million kilometres (0.23 astronomical units) away, though it will then be a very tough spot in the pre-dawn from the UK owing to its very low position over the eastern horizon as twilight starts to gather.

The comet currently gives every indication that it’s very active. It has evolved dramatically over the past month or so, gaining around four magnitudes. Recent images, such as the marvellous image here from Michael Jäger, show it now sports an intensely green coloured coma that may have quadrupled in angular diameter (to ~16’ at its extremities), and a fine tail, the faintest traces of which stretch at least a couple of degrees away to the north-west. Visually, the coma is seen to span between 4’ to 8’, its size being dependant on aperture and local sky conditions.

Comet 2021 A1 Leonard shows tremendous style in this superb image shot on 25 November. The comet was located in Canes Venatici; the attractive galaxies seen here are NGC 4656, closest to the comet’s nucleus, and NGC 4631, with companion NGC 4627. Image: Michael Jäger.

You’ll have to be prepared to rise from a warm bed or be a bit of a night owl in order to see comet 2021 A1 (LEONARD). However, this doesn’t seem to me to be much of an imposition as it’s only around for 10 days or so. Also the comet is already the brightest icy visitor of the year, with potential for it to shine as bright as magnitude +4, and this is the only chance we’ll ever get to see comet 2021 A1 (LEONARD) before its unceremoniously chucked out of the Solar System.

Comet 2021 A1 (Leonard) rockets across the sky while it’s visible from UK shores for the first ten days or so of December. It then plummets south on its way to perihelion in early January next year. All AN graphics by Greg Smye-Rumsby.

At the start of December, comet 2021 A1 (LEONARD) lies in southern Canes Venatici close to the boundary with Coma Berenices, tracking south-eastwards by about 5” per minute relative to the background stars. By 3am GMT, the comet lies around 30 degrees clear of the eastern horizon.

Comet 2021 A1 (Leonard) passes under 10’ south of the bright globular cluster Messier 3 in Canes Venatici on the morning of 3 December 2021 (times GMT).

There’s a real observing treat for visual observers and astro-imagers alike when on the morning of 3 December comet 2021 A1 (LEONARD) slides just south of mighty Messier 3, the great globular cluster in Canes Venatici; the pair are closest at around 4am, when the comet, which hopefully will have brightened by now to around magnitude +6, lies around 7’ south of M3. If your observing location is cloud-free for long enough and has a reasonably unobstructed view to the east, you’ll be able to see in real time as the comet’s rapid apparent motion of around 6” per minute takes it past M3 between about 2am and 6am GMT.

Comet 2021 A1 (LEONARD) enters Boötes on 4 December and lies just over five degrees north of brilliant Arcturus (alpha Boötis) on the morning of 6 December. For once the astronomical gods are smiling down upon us, as the Moon is new at around dawn on 4 December and won’t infer for the rest of the comet’s morning showing. The comet’s plunge south-eastwards means it’s losing altitude from UK skies; you’ll now need to wait an hour longer than at the beginning of December, until around 4am GMT, for comet 2021 A1 (LEONARD) to achieve an altitude of 30 degrees. By 8 December, the comet’s travelling with an apparent motion of 15” per minute and can be located in the far east of Boötes, around three degrees east of magnitude +5.4 xi Boötis. Astronomical twilight begins from London shortly before 6am GMT, with the comet around 30 degrees up. Earth crosses the orbital plane of the comet on 8 December, which will enhance the tail.

The morning of 10 December is realistically your last chance to catch comet 2021 A1 (LEONARD) while observing circumstance from the UK are still reasonable. The comet is now located in Serpens Cauda, around 5.5 degrees north-east of magnitude +2.6 Unukalhai (alpha Serpentis) and it now rocketing across the sky at over 21” per minute. If expectations are fulfilled, comet 2021 A1 (LEONARD) will be shining at around magnitude +4

Following close approach on 12 December, comet 2021 A1 (LEONARD) moves into the dusk sky a few days later and can soon be seen from the Southern Hemisphere. In Sydney, Australia, the comet can be seen from around 21 December when it lies among the stars of Microscopium, some 20 degrees high in the west-south-west at about 9.10pm AEDT (at the end of nautical twilight when the sky is reasonably dark). Its apparent motion across the sky has now dropped below 10” per minute. Comet 2021 A1 (LEONARD) steadily gains altitude in the dusk in the run-up to perihelion, entering Piscis Austrinus on 30 December.

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Weather forecast favorable for SpaceX launch this week – Spaceflight Now

A Falcon 9 rocket streaks into the sky over Cape Canaveral during a launch with Starlink satellites in March 2021. Credit: SpaceX

Forecasters predict a 90% chance of good weather Wednesday night at Cape Canaveral for launch of a SpaceX Falcon 9 rocket with a fresh group of Starlink internet satellites.

SpaceX is readying a Falcon 9 launcher for liftoff at 6:20 p.m. EST (2320 GMT) Wednesday from pad 40 at Cape Canaveral Space Force Station. The two-stage launcher will place another batch of Starlink satellites into orbit a few hundred miles above Earth at an inclination of 53.2 degrees to the equator.

Mostly clear skies and mild temperatures are expected Wednesday evening, according to an outlook from the U.S. Space Force’s 45th Weather Squadron.

The forecast team says a “rather benign weather regime” will remain in place on Florida’s Space Coast through the middle of the week.

“Surface high pressure is expected to develop over the western Gulf of Mexico and will extend into the southeastern U.S.,” forecasters wrote in a launch weather forecast. “As a result, there will be light winds during the launch window and limited low-level moisture. The primary concern for a Wednesday evening launch is a few cumulus clouds with the onshore flow.”

Winds are predicted to be from the northeast at 10 to 15 mph, with a temperature of around 70 degrees Fahrenheit for the instantaneous launch window Wednesday. Forecasters expect identical weather conditions during a backup launch opportunity Thursday evening.

SpaceX rolled out the Falcon 9 rocket for the next Starlink mission from its hangar Monday and erected it vertical on pad 40. A static fire test is planned as soon as Monday night, when SpaceX’s launch engineers will oversee the loading of kerosene and liquid oxygen into the two-stage rocket for a brief on-pad firing of the Falcon 9’s Merlin main engines.

Hold-down clamps will keep the rocket on the ground as the nine Merlin 1D engines throttle up to produce 1.7 million pounds of thrust. The test-firing will last less than 10 seconds.

The mission will use a previously-flown booster from SpaceX’s Falcon 9 inventory. But SpaceX hasn’t yet confirmed which booster is assigned to the Starlink mission, which is designated Starlink 4-3.

SpaceX also has not confirmed the number of Starlink satellites on-board the 229-foot-tall (70-meter) rocket. The previous Starlink mission, which kicked off deployment of a new phase of the Starlink network, carried 53 satellites, all with inter-satellite laser links.

The Nov. 13 launch of the Starlink 4-1 mission was the first to go into a new “shell” some 335 miles (540 kilometers) above Earth.

Most of the Starlink satellites launched so far have deployed into a 341-mile-high (550-kilometer), 53-degree inclination orbit, the first of five orbital shells SpaceX plans to complete full deployment of the Starlink network. SpaceX finished launching satellites in that shell with a series of Starlink flights from Cape Canaveral from May 2019 through May of this year.

Since May, SpaceX has rushed to complete development of new inter-satellite laser terminals to put on all future Starlink satellites. The laser crosslinks, which have been tested on a handful of Starlink satellites on prior launches, will reduce the reliance of SpaceX’s internet network on ground stations.

The ground stations are expensive to deploy, and come with geographical — and sometimes political — constraints on where they can be positioned. Laser links will allow the Starlink satellites to pass internet traffic from spacecraft to spacecraft around the world, without needing to relay the signals to a ground station connected to a terrestrial network.

SpaceX is currently providing interim internet services through the Starlink satellites to consumers who have signed up for a beta testing program.

In September, SpaceX launched the first batch of 51 Starlink satellites into a 70-degree inclination orbit on a Falcon 9 rocket from Vandenberg Space Force Base. That orbital shell will eventually contain 720 satellites at an altitude of 354 miles (570 kilometers).

Aside from the 53-degree and 70-degree orbital shells, SpaceX’s other Starlink layers will include 1,584 satellites at 335 miles (540 kilometers) and an inclination of 53.2 degrees, and 520 satellites spread into two shells at 348 miles (560 kilometers) and an inclination of 97.6 degrees.

The mission Wednesday will be the second Starlink flight to target the 53.2-degree inclination orbit, slightly offset from the 53-degree inclination planes populated during the first phase of the Starlink network deployment.

SpaceX has regulatory approval from the Federal Communications Commission for approximately 12,000 Starlink satellites. The company’s initial focus is on launching 4,400 satellites on a series of Falcon 9 rocket flights. SpaceX’s next-generation launcher, a giant rocket called the Starship that has not yet reached orbit, may eventually be tasked with launching hundreds of Starlink satellites on a single mission.

The launch Wednesday will be the 32nd Falcon 9 flight dedicated to hauling satellites into orbit for the Starlink program.

It will also be the 27th Falcon 9 launch overall this year, exceeding a mark of 26 Falcon 9 missions SpaceX completed in 2020.

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Follow Stephen Clark on Twitter: @StephenClark1.

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NASA Simulation Shows What Happens When Stars Get Too Close to Black Holes

What happens to a star when it strays too close to a monster black hole? Astronomers have wondered why some stars are ripped apart, while others manage to survive a close encounter with a lurking black hole, only a little worse for wear.

To figure out the dynamics of such an event, scientists built a supercomputer simulation and tested it out on eight different types of stars. The stars were sent towards a virtual black hole, 1 million times the mass of the Sun.

What they found was surprising.

The stars they modeled ranged in size from about one-tenth to 10 times the Sun’s mass, all with varying densities. All the stars were sent to about 24 million miles away from the black hole at their closest.

The good news is that the Sun-like star survived its close approach (good news for us, anyway). The other stars that survived had 0.15, 0.3, and 0.7 solar masses. But the stars that were 0.4, 0.5, and 3, and 10 times the Sun’s mass were completely torn apart.

Why the disparity?

The researchers realized it wasn’t the star’s size that made the difference for its survival. Instead, the difference between survival and destruction was dependent on the star’s internal density. You can see the details in this video from NASA:

In the simulation above, yellow represents the greatest densities, blue the least dense.

These simulations were led by Taeho Ryu, from the Max Planck Institute for Astrophysics in Garching, Germany. NASA says these simulations are the first to combine the physical effects of Einstein’s general theory of relativity with realistic stellar density models.

The results will help astronomers estimate how often full tidal disruptions occur in the universe and will aid them in building more accurate pictures of these catastrophic events.

You can see all the various simulations here, from NASA’s Scientific Visualization Studio at Goddard Spaceflight Center.

Read the team’s paper, published in the Astrophysical Journal.

Lead image caption: From left to right, this illustration shows four snapshots of a virtual Sun-like star as it approaches a black hole with 1 million times the Sun’s mass. The star stretches, looses some mass, and then begins to regain its shape as it moves away from the black hole. Credit: NASA’s Goddard Space Flight Center/Taeho Ryu (MPA)

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Astronomers Watch Black Hole Jet Launch – Sky & Telescope

When X-rays flared from an area of the sky previously thought to be empty in March 2018, they triggered an early alert system. Astronomers around the world stopped what they were doing to turn six telescopes, including one aboard the International Space Station, toward the flare.

In the resulting observations, which ranged from radio to X-rays, Alex Tetarenko (Texas Tech University) and her collaborators caught something never seen before: the creation and launching of jets from a black hole, named MAXI J1820+070, about 10,000 light-years away in our galaxy. With observations in hand, they calculated physical properties of the jet, such as its distance and motion relative to the black hole.

“Jet materials alter the chemistry of interstellar gas and affect galaxy and star formation,” Tetarenko explains. “They also provide laboratories to test fundamental physics, so understanding what causes them is so important.”

Black Hole Jets

Stellar-mass black hole with accretion disk and jet
In this artist’s impression, a black hole is pulling in material from a companion star through an accretion disc. Some of that plasma escapes through a jet.
Gabriel Pérez Díaz (Instituto de Astrofísica de Canarias)

Most of the black holes we’ve discovered inside our galaxy have been detectable because they have a stellar companion. As a black hole pulls matter from its companion, the matter spirals inward, losing energy and emitting X-rays, just before entering the maw.

Jets then erupt from the black hole’s poles, propelling particles with such concentrated force that they fly out at relativistic speeds to light-years away, emitting radio waves that can be detected from Earth.

Astronomers have observed jets around black holes large and small — recently, for example, the Event Horizon Telescope captured sharp images of jets from the supermassive black hole M87*. But questions remain as to jets’ origins. Namely, where does all the jet-launching power come from?

M87 jet
The Event Horizon Telescope obtained an unprecedentedly sharp image of the jet shooting out from the supermassive black hole in M87. But supermassive black holes and their jets usually change on timescales longer than human lifetimes. Around stellar-mass black holes, astronomers can watch such changes on shorter timescales.
Radboud University; ESO / WFI; MPIfR / ESO / APEX / A. Weiss et al.; NASA / CXC / CfA / R. Kraft et al.; EHT / M. Janssen et al.

There are two competing theories: The jets could be extracting energy and angular momentum from the magnetic fields that thread the spinning black hole’s event horizon, or magnetic fields anchored in the materials swirling into the black hole could provide the needed power.

In order to answer these questions, we need to watch a full cycle to see a jet launch and extinguish. Stellar-mass black holes offer this opportunity because they run through an entire cycle in a few months, instead of taking millions of years as supermassive black holes do.

Mapping the Jet

MAXI J1820 flared when it caught an extra gob of gas from its stellar companion, which is about half the mass of the Sun. The team measured the outburst across a broad spectrum of wavelengths from X-rays to radio waves. Using a timing analysis method, they were finally able to resolve the tiny details of MAXI’s jets.

“The technique . . . is analogous to how ships use sonar to map underwater objects,” explains Tetarenko, “Except here, we use the timing signals propagating from inflow to outflow as ‘black hole sonar’ to map the jet structures.”

Timing analysis revealed the base height of the jets, their angle, and speed. This is important since properties like the magnetic field strength depend highly on the geometry.

X-ray observations of stellar-mass black hole
Observations from NASA’s Chandra X-ray Observatory taken in 2018 and 2019 (shown in inset) allowed astronomers to detect the black hole’s jets.
X-ray: NASA / CXC / University of Paris / M. Espinasse et al.; Optical / IR: PanSTARRS

Calculations showed that MAXI J1820’s jets launched a mere light-second (300,000 km) away from the black hole, about 1,000 times closer than Earth is to the Sun. So close to the black hole, the jets are extremely narrow, opening at just 0.45 degrees, the narrowest angle measured to date.

Based on these results, published in the Astrophysical Journal, Andrzej Zdziarski (Polish Academy of Sciences), Tetarenko, and Marek Sikora (also at Texas Tech) think the black hole might be responsible for powering the jet. The energy the jet carries is consistent with theoretical predictions from the black hole spin scenario, Tetarenko says.

Tetarenko expects that deeper investigations into the data, as well as observations of more black hole systems, will help confirm the result.

“By simultaneously studying how the emission of the black hole X-ray binary changes from one part of the electromagnetic spectrum to another, Alex and her collaborators succeed in accurately measuring something that has never been possible in the past to this precision,” notes Sara Motta (University of Oxford, UK), who wasn’t involved in the study. “This is crucial to constrain the fundamental physics ruling the jet generation and launching mechanism.”


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On This Day in Space! Nov. 28, 1967: Astronomers Discover the 1st Pulsar

On Nov. 28, 1967, astronomers found the first pulsar.

A pulsar is a super-dense star that rotates super fast. As the pulsar spins, it emits two beams of light in opposite directions. When astronomers look at a pulsar, it looks like a star that’s flickering on and off at a steady, constant pace.

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NASA Weekly ISS Space to Ground Report for 26 November, 2021


NASA Weekly ISS Space to Ground Report for 26 November, 2021.

NASA’s Space to Ground is your weekly update on what’s happening aboard the International Space Station.

Got a question or comment? Use #AskNASA to talk to us.

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Status Report

NASA Weekly ISS Space to Ground Report for 26 November, 2021

NASA’s Space to Ground is your weekly update on what’s happening aboard the International Space Station.

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Northrop Grumman proposes lunar rover for Artemis program

An illustration of Northrop Grumman's Lunar Terrain Vehicle rover design it is proposing for NASA's Artemis program. Credit: Northrop Grumman

An illustration of Northrop Grumman’s Lunar Terrain Vehicle rover design it is proposing for NASA’s Artemis program. Credit: Northrop Grumman

A team of companies led by Northrop Grumman has put forth a proposal for an astronaut-driven lunar rover for the agency’s Artemis Moon program.

Earlier this year, NASA asked American companies for input on approaches for surface transportation at the Moon’s south pole by proposing a Lunar Terrain Vehicle, LTV, which would be used for multiple Artemis missions over at least 10 years.

“Most people do a lot of research before buying a car,” said Nathan Howard, project manager for the LTV at NASA’s Johnson Space Center via an Aug. 31, 2021, news release. “We’re doing extensive research for a modern space vehicle that will be provided by industry. As we plan for long-term exploration of the Moon, the LTV won’t be your grandfather’s Moon Buggy used during the Apollo missions.”

The Artemis program LTV will need to operate in extreme environments, drive autonomously, surviving long cold lunar nights and have an open, unenclosed design so astronauts can drive on the Moon while in their spacesuits.

NASA expects the design will incorporate advances in electric vehicle capabilities and be able to transport cargo as well as crew.

Recently, Northrop Grumman, in partnership with ALV, Intuitive Machines, Lunar Outpost and Michelin, proposed an LTV design that can support human and robotic exploration of the Moon’s surface and on to Mars.

The company said the team brings flight-proven technologies and expertise, including navigation, avionics, mission planning, system training and storage solutions.

A rendering of several lunar rovers on the Moon's surface at the proposed Artemis Base Camp at the lunar south pole. Credit: Northrop Grumman

A rendering of several lunar rovers on the Moon’s surface at the proposed Artemis Base Camp at the lunar south pole. Credit: Northrop Grumman

“Together with our teammates, we will provide NASA with an agile and affordable vehicle design to greatly enhance human and robotic exploration of the lunar surface to further enable a sustainable human presence on the Moon and, ultimately, Mars,” said Steve Krein, vice president of civil and commercial space, tactical space systems division at Northrop Grumman in a company press release on Nov. 16.

Intuitive Machines is a supplier of space services and goods, with previous expertise obtained through the development of NASA’s Commercial Lunar Payload Services. The company is expected to contribute by developing the Nova-D lander, which is expected to be capable of delivering up to 1,100 pounds (500 kilograms) of payload to the Moon’s surface.

AVL has expertise in electrical drive solutions, autonomous driving development, simulation and testing of propulsion systems as a leader in the advancement of battery systems. The company can also contribute with the build of specific tools and technology needed to enable the LTV to operate successfully off Earth.

Lunar Outpost is expected to help resolve unique challenges the spacecraft may encounter by mobility platforms on the lunar surface by providing dust mitigation and thermal technologies and through the company’s line of planetary rover products.

Michelin, meanwhile, is charged with delivering an airless tire design for the LTV, drawing on the company’s previous experiences with NASA.

Northrop Grumman has a deep heritage of contributions to space exploration including contributions to the Apollo program, the Cygnus spacecraft, and the Habitat and Logistics Outpost module for the Lunar Gateway, which itself is part of the Artemis program.

Video courtesy of Northrop Grumman

Tagged: Artemis program Intuitive Machines Lunar Terrain Vehicle Northrop Grumman Nova-D The Range

Theresa Cross

Theresa Cross grew up on the Space Coast. It’s only natural that she would develop a passion for anything “Space” and its exploration. During these formative years, she also discovered that she possessed a talent and love for defining the unique quirks and intricacies that exist in mankind, nature, and machines.

Hailing from a family of photographers—including her father and her son, Theresa herself started documenting her world through pictures at a very early age. As an adult, she now exhibits an innate photographic ability to combine what appeals to her heart and her love of technology to deliver a diversified approach to her work and artistic presentations.

Theresa has a background in water chemistry, fluid dynamics, and industrial utility.

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