Liftoff is scheduled for 7:50 a.m. EDT on Thursday (July 30). By Mike Wall @Space.com
NASA’s next Mars rover has been cleared for liftoff.
This morning (July 27), the $2.7 billion Mars 2020 Perseverance rover passed its launch readiness review, the last big hurdle to clear before its planned liftoff Thursday (July 30) from Florida’s Cape Canaveral Air Force Station.
“The launch readiness review is complete, and we are indeed go for launch,” NASA Administrator Jim Bridenstine said during a news conference today.
Perseverance is scheduled to lift off atop a United Launch Alliance Atlas V rocket Thursday during a two-hour window that opens at 7:50 a.m. EDT (1150 GMT). You can watch all the action live here at Space.com, courtesy of NASA.
Mother Nature looks likely to cooperate with that plan. There’s just a 20% chance that bad weather will scuttle Thursday’s attempt, launch weather officer Jessica Williams, of the 45th Space Force, said during today’s news conference.
The launch will send Perseverance on a nearly 7-month cruise to Mars, which will end with a dramatic, sky-crane landing within the Red Planet’s Jezero Crater on Feb. 18, 2021.
The nuclear-powered rover will then spend at least one Mars year (nearly two Earth years) exploring the 28-mile-wide (45 kilometers) Jezero, which harbored a lake and a river delta in the ancient past. Perseverance will hunt for signs of ancient Mars life, study the crater’s geology and collect and cache several dozen samples, among other tasks.
Those samples will be brought back to Earth, perhaps as early as 2031, by a joint NASA/European Space Agency campaign. Once the Mars material is here, scientists around the world will scour it for signs of life and clues about the planet’s mysterious history.
“That’ll be the first time in history that we’ve done a Mars return mission,” Bridenstine said. “In fact, it’s the first time in history we’ve done a return mission from any planet.”
(Humanity has pulled off other types of sample-return missions, however. NASA’s Apollo astronauts brought hundreds of pounds of rocks back from the moon, and robotic probes have returned to Earth with asteroid material and specks of comet dust.)
Perseverance will also demonstrate several new technologies on the Martian surface. For example, one of the rover’s 10 instruments, called MOXIE, will generate oxygen from the Red Planet’s thin, carbon dioxide-dominated atmosphere. Such gear, once scaled up, could help future astronauts explore the Red Planet, a goal NASA wants to achieve in the 2030s.
In addition, a 4-lb. (1.8 kilograms) helicopter called Ingenuity will travel to Mars on Perseverance’s belly. Once the rover finds a good spot, the little chopper will detach and perform a few test flights — the first ever performed by a rotorcraft on an alien world.
If Ingenuity is successful, future Mars missions may routinely employ helicopters as scouts for rovers or astronauts, NASA officials have said. Rotorcraft could also do substantial science work of their own, exploring hard-to-reach places such as caves and cliff faces.
Ingenuity won’t collect data in this manner; it carries no science instruments. But the little chopper does have a camera system, which should provide some amazing and unprecedented Red Planet views.
“Imagine looking from Perseverance out at a helicopter that is flying around Perseverance, and the helicopter is looking back at Perseverance, giving us images of Perseverance — what Perseverance is doing,” Bridenstine said. “We’re going to be able to see with our own eyes, with motion pictures, these kinds of activities happening on another world.”
Perseverance’s launch window extends through Aug. 15. If the rover is unable to get off the ground by then, it will have to be put into storage until the next opportunity in 2022. (Earth and Mars align properly for interplanetary missions for a few weeks every 26 months.)
The NASA rover’s launch will be the third Mars liftoff in less than two weeks. The United Arab Emirates’ Hope orbiter launched on July 19, and China’s Tianwen-1 orbiter-lander-rover mission followed suit on July 23.
(Image credit: NASA/Johns Hopkins APL/Naval Research Lab/Parker Solar Probe/Brendan Gallagher)
Comet NEOWISE has is delighting skywatchers around the Northern Hemisphere. But what makes this comet so special? Advertisement
The comet made its closest approach to the sun on July 3 but, until now, was only visible in the sky before dawn. Now, for keen observers in the Northern Hemisphere, the comet has been getting higher in the evening sky, sparkling northwest below the Big Dipper constellation, according to Joe Masiero, deputy principal investigator of NEOWISE (NASA’s Near-Earth Object Wide-field Infrared Survey Explorer, the NASA space telescope that first spotted the comet).
One of the most fascinating details about Comet NEOWISE is that it won’t return to our skies for another 6,800 years. But that’s not the only thing that makes this icy space rock special. So let’s take a dive into what makes Comet NEOWISE unique — and a little weird.
Officially known as C/2020 F3, Comet NEOWISE is a comet that was discovered on March 27, 2020, by NEOWISE, the asteroid-hunting afterlife of the Wide-field Infrared Survey Explorer (WISE) mission.
Comets, often nicknamed “cosmic snowballs,” are icy, rocky objects made up of ice, rock and dust. These objects orbit the sun, and as they slip closer to the sun most comets heat up and start streaming two tails, one made of dust and gas and an “ion tail” made of electrically-charged gas molecules, or ions.
Can I see it?
Yes! Because it is especially bright, the comet is visible in the night sky with the naked eye. Skywatchers in the Northern Hemisphere can spot the object just after sunset, to the northwest just under the Big Dipper constellation.
In fact, the comet is so bright that scientists are “able to get a lot more and better data than we typically do for most comets,” Kramer said. “We’re able to study it with a wide variety of different telescopes, and that’ll allow us to do really interesting studies.”
Do I need a telescope?
No! Because Comet NEOWISE is an especially bright object, it is relatively easy for astronomy enthusiasts to spot it in the night sky with just the naked eye, although binoculars or a small telescope will give you a better view.
“The fact that we can see it is really what makes it unique,” Kramer said. “It’s quite rare for a comet to be bright enough that we can see it with a naked eye or even with just binoculars.”
What does it look like in the sky?
To those spotting the comet with the naked eye, without any tools or instruments like a telescope, it looks like a fuzzy star with a little bit of a tail. You do need to be away from city lights, though.
With binoculars or a small telescope, the comet will be more clear and the tail will be easier to spot.
How much water is in the comet?
There is “about 13 million Olympic swimming pools of water,” in Comet NEOWISE, Emily Kramer, a science team co-investigator forNASA’s NEOWISE at NASA’s Jet Propulsion Laboratory, said during a news conference July 15. “So that’s a lot of water.”
“Most comets are about half water and half dust,” she added.
Does it have a tail?
Comet NEOWISE has two tails that typically accompany every comet.
As a comet nears the sun, it warms up and material pulls away from the surface into a tail. Often, dust is pulled away along with gases from sublimating (going directly from solid to a gas) ice. This dust tail is the sweeping trail seen in most comet images. Comets also have an ion tail made up of ionized gas blown back by the solar wind.
Researchers studying Comet NEOWISE might actually also have a sodium tail. By observing what they believe to be atomic sodium in the comet’s tail, researchers can glean keen insight into the object’s makeup.
How big is Comet NEOWISE?
Comet NEOWISE is about 3 miles (5 kilometers) in diameter, “which is a reasonably large but roughly average-size comet,” Kramer said.
“It’s rare to see something that’s this bright,” she added. “There are comets that are of this size that we see regularly, but most of them are so from Earth that they don’t get this bright. They’re too far from the sun and the Earth to be able to see them in the way that we’re seeing this Comet NEOWISE.”
How fast is Comet NEOWISE?
The comet is traveling at about 40 miles per second (that’s about 144,000 mph, or 231,000 km/h).
Joe Masiero, deputy principal investigator of the NEOWISE mission, said the the comet is moving about twice as fast as the Earth’s speed around the sun. But don’t expect that rapid clip to last.
Because of the comet’s extremely elliptical orbit, it will slow down as it reaches its farthest point from the sun, then fall back toward the inner solar system and accelerate again when it heads back round the sun. That trip around the sun is over for Comet NEOWISE’s current orbit and it’s moving back to the outer solar system.
“And so as it goes farther from the sun, [it] will be slowing down as it climbs back up that gravity well,” Masiero said.
Will it hit Earth?
Have no fear, Comet NEOWISE will not hit Earth.
“This particular comet has no possibility of impacting the Earth. It crosses the plane of Earth orbit well inside of recovery orbit and almost near the orbit of Mercury, so there’s absolutely no hazard from this comet,” Lindley Johnson, the planetary defense officer and program executive of NASA’s Planetary Defense Coordination Office at NASA Headquarters, said during the news conference.
The comet orbits the sun every 600 to 700 years, Johnson said. The comet is currently about 70 million miles (111 million kilometers) away from Earth.
Is it from interstellar space?
No, Comet NEOWISE originates in our own solar system. To date, only two interstellar objects have been discovered: ‘Oumuamua and Comet Borisov.
“This one we know it’s not Interstellar object. By watching its motion, we can see that it’s bound to the sun’s gravity,” Kramer said. “So it’s coming in very rapidly and then it’s going to go far back out again and then but then should come back in again in about 6,800 years.”
Email Chelsea Gohd at firstname.lastname@example.org or follow her on Twitter @chelsea_gohd. Follow us on Twitter @Spacedotcom and on Facebook.
Rivals to send spacecraft to the red planet just days apart, as China seeks to challenge the U.S. on exploration
SHANGHAI—The rivalry between the U.S. and China assumes cosmic proportions this month, as both countries prepare to send spacecraft to Mars within days of each other.
The head-to-head Mars missions are the latest sign that China is ready to challenge the U.S. in space exploration, in recent decades an American preserve.
China’s first mission to another planet, the Tianwen-1 is set to blast off this week—the exact day has yet to be announced—on a seven-month journey to Mars. It will orbit the red planet for two to three months before deploying a rover that will conduct scientific experiments on the Martian surface.
The U.S. mission, due to launch July 30, will land the Perseverance rover on Mars. It will also deploy the Ingenuity Mars helicopter—the first craft capable of powered flight on another planet.
Chinese officials have framed space exploration as a contest between nations and sometimes likened the conquest of space to China’s territorial disputes here on Earth.
This summer the planets favorably align for spacecraft to reach Mars with the least amount of fuel. China is among the countries undertaking the mission while working on bigger ambitions that could one day challenge the U.S.’s leadership in space. Photo Composite: Crystal Tai
“The U.S. is clearly uncomfortable with the idea that China could overtake it in all manner of ways,” said Dean Cheng, a senior research fellow at the Heritage Foundation, a U.S. think tank. “It matters to the U.S. psyche that it stays ahead in space.”
President Xi Jinping has put China’s national space program at the heart of a quest for “great rejuvenation” after a century of perceived humiliation in which China fell behind the West. In a letter to Chinese space scientists published this year, Mr. Xi urged China’s space scientists to “achieve the early realization of the great dream of building a powerful space nation.”
China first put a man into space in 2003, more than four decades after Russia and the U.S., but since then its space program has steadily chalked up new milestones.
There have been setbacks, too: The failure of China’s new Long March 5 heavy-lift rocket during a 2017 test set back the country’s space program by a couple of years. But two successful flights in December and May suggest the rocket’s glitches have now been resolved. The Long March 5 will power this week’s Mars mission, and put a planned Chinese space station into orbit by 2022.
By 2030, China aims to have collected Martian rock samples and returned them to earth, and it wants a manned lunar base and the capability to send men to Mars by 2045.
The timing of this month’s launches is primarily dictated by the motion of the planets.
Every 26 months, the Earth and Mars swing relatively close to one another—if 34 million miles can be considered close—providing a narrow window for Martian missions. The United Arab Emirates also took advantage of the latest alignment by launching a Mars probe Sunday. The U.S. and Russia have launched multiple probes to Mars in the past, while Europe, India and Japan have also sent spacecraft there.
The latest American Mars mission will gather samples for return to Earth on a future mission. The U.S. then aims to put astronauts back on the moon by 2024, and to launch a manned Mars mission in the 2030s. The Science and Technology Policy Institute said last year that the U.S. could realistically aim to launch a manned Mars mission in 2037 at the earliest, at a cost of more than $120 billion.
NASA’s Perseverance Mars rover late last year during testing in Pasadena, Calif.PHOTO: NASA/AGENCE FRANCE-PRESSE/GETTY IMAGES
China’s one-party system provides a measure of certainty for the country’s space program, whereas National Aeronautics and Space Administration missions have sometimes fallen victim to shifts in spending priorities with new administrations. However, the U.S. has the advantage of a flourishing space private sector—led by companies such as SpaceX and Blue Origin—that China so far hasn’t been able to replicate.ADVERTISEMENT
The race to land astronauts on the moon is highly symbolic, said Mr. Cheng of the Heritage Foundation, with relations between the world’s two largest economies at their lowest ebb in decades as Beijing and Washington spar over issues ranging from technology and trade to the political status of Hong Kong and human rights in Xinjiang in China’s far west.
Last year, the U.S. created a military Space Force to counter space-based threats, chiefly from China and Russia. A Chinese Foreign Ministry spokesman said at the time that the U.S.’s new military branch would “pose a direct threat to outer space peace and security.”
Even though the U.S. won the original race to the moon long ago, it would be politically embarrassing for the U.S. should China be the first to get there in the 2020s, Mr. Cheng said. Likewise, either country faces humiliation should its Mars mission fail while the other succeeds.
Roughly half of the missions sent to Mars since exploration of the planet began in the 1960s have failed. Most recently, the European Space Agency’s Schiaparelli lander was destroyed when it crashed into the Martian surface in 2016, though the U.S. successfully reached Mars with its InSight lander two years ago.
As SpaceX readies beta-testing for its Starlink broadband service, Internet users have dug into the Starlink website and found new details on the upcoming beta tests and images of the user terminals that will be installed outside customers’ homes.
SpaceX CEO Elon Musk wrote on Twitter last night that the latest version of the dish (also called a user terminal) looks slightly different than what is seen in the photos. “Small note: latch on post near base is gone & powered Ethernet wire is less obtrusive in production version,” Musk wrote.
Musk has previously described the terminal as a “UFO on a stick.” SpaceX received Federal Communications Commission approval to deploy 1 million of them. The terminal’s size is 0.48 meters (almost 19 inches), according to an FCC filing.
SpaceX recently updated the Starlink website with a form you can fill out to “get updates on Starlink news and service availability in your area.” Public beta tests are expected to begin in the fall.
The Starlink FAQ posted on Reddit says that “Starlink Beta will begin in the Northern United States and lower [i.e. southern] Canada, with those living in rural and/or remote communities in the Washington state area. Access to the Starlink Beta program will be driven by the user’s location as well as the number of users in nearby areas.”
Describing the current satellite network and the need for beta testers to have a clear view of the sky from their homes, the FAQ says, “The Starlink system is currently made up of nearly 600 satellites orbiting the Earth that can provide Internet service in a very specific range—between 44 and 52 degrees north latitude. Your Starlink dish requires a clear view of the Northern sky in order to communicate with the Starlink satellites. Without the clear view, the Starlink dish cannot make a good connection and your service will be extremely poor.”
In another tweet yesterday, Musk noted that the “Starlink terminal has motors to self-orient for optimal view angle,” eliminating the need for an expert installer. The terminal can be placed “in garden, on roof, table, pretty much anywhere, so long as it has a wide view of the sky,” Musk wrote. He also wrote that once service is available, it “will take less than a minute to order on Starlink.com.”
Beta testers are asked to “dedicate an average of 30 minutes to 1 hour per day testing the Starlink Services and providing feedback on a periodic basis,” according to the terms of service. “Feedback requests from SpaceX will come in the form of surveys, phone calls, emails, and other means. Not participating can result in termination of your Beta Program participation and you must return your Starlink Kit.” Beta testers will not be allowed to share anything about their use of the service publicly.
An FCC filing says the router is dual-band, supporting 2.4GHz and 5GHz transmissions. It supports the 802.11ac Wi-Fi standard with data-transfer rates of up to 866.7Mbps, in addition to older standards including 802.11b, 802.11a/g, and 802.11n.
Alyssa Carson is part of a group of young people working to position themselves to be the first astronauts to go to Mars.
Carson, who is now 19, has attended every NASA space camp and was the youngest person to graduate from the Advanced Space Academy.
Alyssa Carson attended her first space camp at 5 years old. She graduated from the Advanced Space Academy program at 16, the youngest person ever to do so. Before the pandemic hit, the rising college sophomore had planned to spend her summer flying airplanes.
The eventual goal: fly to Mars.
Carson is one of a small group of young people who are already positioning themselves to be astronauts in the US’s next phase of space exploration. They are attending advanced preparation programs and building social media personas to put themselves on NASA’s radar now, all with an eye towards being in the astronaut class sent to the red planet in the next couple of decades.
The group, mostly teenagers, talks online about the latest developments in space exploration and works to broadcast their interest to a wider audience. Carson’s online personality is NASA Blueberry — she uses the name on Twitter, Instagram, and TikTok.
“We’re kind of translating space talk and doing science experiments on TikTok,” she told Business Insider. “It’s definitely a lot of the science geeks trying to learn this new TikTok thing, but it’s about being entertaining while talking about science.”
Going to Mars has been Carson’s dream since she was 3 years old and watched an episode of “The Backyardigans” about astronauts going to Mars. She’s the only person who’s attended every NASA space camp. When she was 12, she was invited to speak at NASA about her interest in the red planet. She’s currently pursuing an astrobiology major at the Florida Institute of Technology.
The draw is that stepping onto the red planet is something no one has done before, she said.
NASA aims to send humans to Mars in the 2030s. A crucial though preliminary step in that effort launches later this month, when the Perseverance rover will begin its journey to the red planet. Assuming it lands there safely, the robot is expected to search for signs of life and measure Mars’s weather, dust, and water conditions. This information could help set up future crewed missions.
‘The Mars generation’
Carson considers herself — and her “science geek” friends — part of the “Mars generation.” For people her age who are into science and space, she said, Mars is the new moon.
But she believes that a push from the public, especially young people, is what’s needed to make sure the mission happens.
“The whole reason why we went to the moon was because there was so much public interest around it,” Carson said. “I definitely think that Mars kind of needs that same push. So it’s kind of either teaching or inspiring or helping people to either want to get involved in the space program in some way or just want to support it.”
NASA Blueberry, the username Carson coined, references her time at the Advanced Space Academy. It’s her “call sign” — the nickname astronauts use for each other when they are giving commands over the radio.
“I got ‘Blueberry’ because the second time I went to space camp, when I was really little, I wanted one of the blue flight suits that I saw everyone wearing because I wanted to be an astronaut, so I wanted to look like one. I was too short and small to fit in any of the flight suits, so my dad ended up finding this knockoff, like not really the right shade of blue,” she explained.
“When I wore it everyone told me it made me look like a blueberry. So after that, throughout the day and the rest of the time at space camp, they would just say, ‘Oh, Blueberry, can you do this?'”
Looking up to women astronauts
Carson said she looks to female astronauts of the past as her role models.
She met former astronaut Sandra Magnus once at a career day for young women interested in science and technology. Magnus chatted with Carson and explained that she’d decided to become an astronaut at a young age.
“That inspired me and told me that it didn’t really matter how old I was when I decided this, that I could actually successfully do it in the future,” Carson said. “So it’s just kind of been a little push and a little motivation to kind of keep me working towards my dream.”
After finishing her schooling — a PhD in astrobiology is a possibility, she said — Carson plans to apply whenever NASA puts out its next call for astronaut applications. The space agency usually accepts applicants every few years.
“Then just hopefully applying until I get selected,” Carson said, adding, “ideally, I just want to contribute in some way to the space program — whether that is the mission to Mars — being on it — or whether that’s doing work on Earth for the mission, or any other mission.”
But her real hope, she said, is to be in space by the time she’s in her 30s.
Those who have gotten up before sunrise to gaze into the twilight skies have been greeted by the best comet performance for Northern Hemisphere observers since the 1997 appearance of Comet Hale-Bopp. Indeed, NEOWISE (catalogued C/2020 F3), emphatically ended the nearly quarter-century lack of spectacular comets.
Early fears of another fizzler like comets ATLAS and SWAN quickly eased during June when NEOWISE proved to be an intrinsically bright comet with a highly condensed core. It brightened 100-fold from June 9, when as a seventh-magnitude object it disappeared into the glare of the sun, to June 27, when it appeared in the field of view of the LASCO-3 camera on NASA’s Solar and Heliospheric Observatory shining at second-magnitude.
Even before Comet NEOWISE arrived at perihelion — its closest point to the sun — observers could glimpse it very low to the northeast horizon, immersed deep in bright twilight, just before sunrise on July 1.
The comet arrived at perihelion on July 3, sweeping to within 27.7 million miles (44.5 million km) of the sun and is now heading back out to the outer reaches of space. Nonetheless, the comet continues to evolve and its tail continues to grow.
Until now, the comet has been accessible only to those waking up at the break of dawn and scanning the sky near the northeast horizon. The comet has appeared to rise tail-first, followed by its bright head or coma, shining as bright as a first-magnitude star. So far, the comet has had to compete with low altitude, bright twilight and the light of a nearly-full moon. Some have been stymied from getting a good look at NEOWISE because of these factors, or perhaps because of poor weather. But things are going to be getting better for skywatchers in the days ahead.
As veteran comet observer Terry Lovejoy commented to Space.com: “The best is yet to come!”
Although the comet is moving away from the sun and beginning to fade, that dimming initially will likely be slow, because it is now approaching the Earth. It will be closest to our planet on the evening of July 22 (“perigee”), when it will be 64.3 million miles (103.5 million km) away. Thereafter, fading will be more rapid as the comet will then be receding from both the Earth and the sun.
The brightness of a sky object is based on magnitude. Bright stars are ranked “first magnitude.” The star Deneb in the Summer Triangle falls into this ranking. The fairly bright stars are of second magnitude. Polaris, the North Star, is a second-magnitude star. A star of third magnitude is considered of medium brightness. Megrez, the star that joins the handle and bowl of the Big Dipper falls into this category.
Based on a special power-law brightness formula, astronomer Daniel Green at the Harvard Smithsonian Center for Astrophysics has forecast how bright NEOWISE should appear in the coming days ahead. His forecast places the comet at first magnitude from now through July 11; second magnitude from July 12 through July 17 and third magnitude from July 18 through July 22.
When and where to look in the morning
As a morning object, the comet’s best views will come during a three-day stretch on the mornings of July 11, 12 and 13, when it will stand 10 degrees above the northeast horizon, 80 minutes before sunrise — the beginning of nautical twilight. Your clenched fist held at arm’s length measures approximately 10 degrees in width. So, on these three mornings, the head of Comet NEOWISE will appear about “one fist” up from the northeast horizon.
The sky should appear reasonably dark at that time with only the light of the last quarter moon providing any interference. As the minutes tick off, the comet will be getting higher, but the dawn sky will be getting increasingly brighter as well.
After July 13, NEOWISE will drop rapidly lower and swing more toward the north-northeast. By July 18, it will appear only 5 degrees above the horizon at the start of nautical twilight. And only a few mornings later its altitude will have become too low to see it at all in pre-sunrise sky.
But as its morning visibility diminishes, there is good news: Comet NEOWISE will become prominent in the evening sky after sunset. That will also mean a much larger audience will be able to see it during “prime-time” viewing hours instead of having to awaken during the wee hours of the early morning.
The first good opportunity for evening viewing begins on July 12, when the head of the comet will stand 5 degrees above the north-northwest horizon, 80 minutes after sunset (the end of nautical twilight). By July 14 its altitude will have already doubled to 10 degrees, and by July 19 it will have doubled yet again to 20 degrees up by the end of nautical twilight. By then it will have moved to above the northwest horizon.
So, we at Space.com feel that the best time to view the comet during the evening will come during the July 14-19 time frame.
We also strongly recommend that observers should seek the most favorable conditions possible. Even a bright comet, like this one, can be obliterated by thin horizon clouds, haze, humid air, smoke, twilight glow and especially city lights. We especially emphasize that last factor: the farther away you get from a metropolitan area, the darker your sky and the better your view of NEOWISE. Binoculars will enhance your view.
And more good news: No moonlight will brighten the sky, as the moon will be a waning crescent and visible only in the morning sky through July 20. On successive July evenings the comet will grow fainter, but it will be farther from the sun, setting later and visible in a darker sky. As we move into August, the comet will be very well placed for observers with small telescopes.
As for the comet’s tail, so far it has displayed a beautiful, gently curved tail of dust which many observers using binoculars and small telescopes have remarked has shown a noticeable yellowish tinge. A much fainter ion (gas) tail accompanies the dust tail. So far the dust tail measures about 4 or 5 degrees in length, but it continues to slowly lengthen and should get more easily seen as viewed against a darker sky and as the comet draws closer to the Earth.
In a comet-watching forum, Minnesota amateur astronomer Bob King wrote: “Comet NEOWISE was astonishingly beautiful this morning (July 7) with a strongly bifurcated (split) tail. Forgive my ignorance, but what causes the bifurcation?” Comet expert John Bortle of Stormville, NY provides us with the answer:
“The dark vacancy that appears to originate just behind the comet’s head and extends up the middle of the dust tail is a fairly rare cometary feature generally referred to by 19th century astronomers as, ‘the shadow of the nucleus.’ Of course, it is not truly a shadow at all, but rather a vacancy in the center of the dust tail, a region largely devoid of cometary dust,” Bortle told Space.com in an email.
“In a sense, one can imagine the tail is like a thick-walled hollow tube with its walls impregnated with reflective dust that is being illuminated by sunlight. Would-be observers of the comet should try to spot this rare feature soon, as it is unlikely to be visible once the comet starts fading significantly,” Bortle added.
What more can we say? It isn’t often we get a sight like this. “COMET get it!”
Joe Rao serves as an instructor and guest lecturer at New York’s Hayden Planetarium. He writes about astronomy for Natural History magazine, the Farmers’ Almanac and other publications. Follow us on Twitter @Spacedotcom and on Facebook.