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NASA’s DART Alters Asteroid’s Course in ‘Watershed Moment for Humanity’

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NASA has succeeded in its mission to change the orbit of asteroid Dimorphos, the space agency’s administrator Bill Nelson confirmed Tuesday. NASA crashed the Double Asteroid Redirection Test spacecraft, aka DART, into Dimorphos a few weeks ago to test one possible method of protecting Earth from a dangerous body on a collision course with our planet.

“This is a watershed moment for planetary defense and a watershed moment for humanity,” Nelson said during a press conference.

To be clear, this was only a test of one potential defense method, called “deflection by kinetic impactor,” that doesn’t require nuclear weapons or celebrities on a suicide mission a la popular Hollywood movies like 1998’s Armageddon. Dimorphos, which is actually a moonlet orbiting the larger asteroid Didymos, doesn’t pose an actual threat to Earth. In fact, no known asteroids or near-Earth objects are considered to be a threat to humanity, but there are still plenty of space rocks and comets out there yet to be discovered or tracked by astronomers.

 

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DART’s impact with Dimorphos on Sept. 26 appears to have reduced the time it takes the moonlet to orbit Didymos by 32 minutes, from 11 hours and 55 minutes to 11 hours and 23 minutes, with a margin of uncertainty of about two minutes. NASA had hoped DART would alter the orbital period by at least 73 seconds but expected it could alter the orbit by at least a few minutes and perhaps tens of minutes. So the result is on the high side of the expected possibilities.

“It looks like the recoil from the ejecta blasted off the surface was a substantial contributor to the overall push given to the asteroid, in addition to the push of the spacecraft directly impacting,” said Tom Statler, DART program scientist at NASA headquarters.

Ejecta is a technical term for the dust and debris thrown off into space as a result of the impact. Numerous images taken in the days that followed the impact by telescopes in space and on Earth showed that the ejecta was forming a tail trailing Dimorphos similar to what we see with comets orbiting the sun.

Nancy Chabot, the DART coordination lead from the Johns Hopkins Applied Physics Laboratory, noted that although the result is considered a resounding success, it still represents only a 4 percent change in the asteroid’s orbital period.

“It just gave it a small nudge, but if you wanted to do this in the future, it could potentially work but you’d want to do it years in advance. Warning time is really key.”

Chabot added that the physical location of Dimorphos also changed ever so slightly and the space stone now orbits Didymos a little more tightly than before the impact.

Scientists on the DART team are continuing to acquire more data from observatories around the world to better understand the dynamics of the impact and its effects.

Later in the decade, the European Space Agency’s Hera project aims to send another spacecraft to conduct detailed surveys of Dimorphos and Didymos, including studying the impact crater left by DART.

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How to see Mars at its brightest at opposition this week

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Stargazers in the northern hemisphere are in for a treat this week as Mars has reached its closest point to Earth, giving the best view of the red planet until the 2030s. Mars made its closest approach to Earth on the night of November 30 to December 1, but the best views are yet to come as the planet reaches a point called opposition on the night of December 7 to December 8. Opposition is when Mars is directly opposite the sun as seen from Earth, which means this is when Mars will be at its brightest.

The reason that the closest approach and opposition are a few days apart is because of the elliptical nature of the planets’ orbits. Neither Earth nor Mars orbits in a perfect circle around the sun, so there are times when they are a little closer or a little further away. These small differences account for the few days’ delay between closest approach and opposition. The elliptical nature of Mars’s orbit is also why there will be such a great view of the planet this week. Mars won’t come back this close to Earth until 2033.

Finder chart for Mars on 8 December. Stuart Atkinson

This diagram from the U.K.’s Royal Astronomy Society shows how to locate Mars in the night sky on the evening of December 8. Mars should be one of the brightest objects in the skies, so if you’re lucky to have clear weather overhead at night then you should easily be able to spot the planet with binoculars or a telescope. At this time, Mars will be around 50 million miles away.

December 8 is also a great time to look for Mars as you may be able to spot the moon moving in front of the planet, called an occultation, depending on where in the northern hemisphere you are located. For exact times to look out for this event by U.S. region, head over to Sky and Telescope for more information.

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According to Sky at Night magazine, you should be able to observe Mars using almost any telescope, but adding a Barlow lens to your setup will give you a better view and enhance the darker and lighter patches on the planet. You may be able to see features on Mars like its polar ice caps, its patches of light and dark which are called albedo features, and perhaps even certain large geological features like basins and plains.

Some of the most dramatic views of Mars will be on the night of December 8, but if that doesn’t work out for you then you should also look to the skies in the week before and after this date as you should still be able to get a good view then.

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Mars at opposition will meet up with the full moon next week (Dec. 7). Here’s how to see it

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Every once in a while, something will appear in the sky that will attract the attention of even those who normally don’t bother looking up.

It’s likely to be that way in the evening hours of Wednesday (Dec. 7) when the full moon will appear in very close proximity to the now-brilliant planet Mars. In fact, the moon will turn full at 11:08 p.m. EST (0408 GMT on Dec. 8) followed by Mars arriving at opposition to the sun just 87 minutes later. This will result in an almost perfect alignment in space of the sun, Earth, moon and Mars.

People, who are unaware or have no advance notice, will almost certainly wonder, as they cast a casual glance toward our nearest neighbor in space on this first Wednesday in December, just what is that “bright orange-yellow light”? Sometimes, such occasions bring with them a sudden rash of phone calls to radio and television stations, local planetariums, weather offices and police precincts. Not a few of these calls excitedly inquire about “the mysterious UFO” that’s closely hovering in the vicinity of our natural satellite!

If you don’t live in any of the locations listed below that will provide a good chance to see the event in person, you’re in luck: The Virtual Telescope Project will be hosting a livestream of Mars at opposition (opens in new tab) beginning at 11:00 p.m. EST on Dec. 7 (0400 GMT on Dec. 8).

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Related: December full moon 2022: The Cold Moon occults Mars

Joe Rao is a veteran meteorologist and eclipse chaser who also serves as an instructor and guest lecturer at New York’s Hayden Planetarium.

 Where to see the moon eclipse Mars

As a bonus, those who are located north and west of a line running roughly from Piedras Negras, Mexico to Louisville, Kentucky to Seabrook, New Hampshire will see the moon occult Mars. Refer to the US map. Those positioned south and east of this line, however, will see the moon miss the planet entirely, barely passing just above it (called an appulse).

But for an observer fortuitously positioned exactly on, or immediately adjacent to that line — it’s actually a narrow path about 21 miles (34 km) wide — the lower limb of the moon will appear to literally graze Mars as it passes by.

For those fortuitously situated along the northern edge of the path, the planet’s dazzling topaz disk may appear to disappear completely, then reappear intermittently in lunar valleys. In contrast, along the southern edge of the path, Mars’ northern edge will only briefly touch the limb of the moon.

Among towns and cities located within the path are Morgantown, WV; Scranton, PA; Hudson, NY; Northampton, MA; Lowell, MA and Seabrook, NH. Refer to the Mars occultation graze path maps.

Unlike a star which is a pinpoint of light and would disappear and reappear in an instant, Mars appears as a small disk in telescopes; owing to its relatively large angular size (17.2 arc seconds in diameter), the occultation will occur at a rather “leisurely” pace. So the disappearance of Mars behind the moon’s bright limb for most places, will take anywhere from about 40 seconds to almost a minute (or even longer where the moon’s limb approaches it at a slant).

From Austin, for instance, the moon’s slow eastward drift will take more than two minutes to completely cover, and later uncover the planet’s disk — and even longer for those to the south and closer in to the northern limit of the graze path, where the moon’s limb will approach at even more of a slant.

The planet’s reappearance will also be gradual. The actual term is called an occultation (Latin for “hiding”). One might even refer to this upcoming event as an eclipse of the planet Mars. Moving to the east against the background stars at its own apparent diameter each hour, the moon will appear to approach Mars from the west (right) and ultimately pass in front of it, and then shortly thereafter, uncover it, and leaving it behind as the moon continues to move to the east.

An illustration of the full Cold Moon as it will appear on Dec. 7, with Mars visible behind it. (Image credit: Starry Night Education)

Plainly visible with just your eyes

An opportunity to see the moon occult a bright planet at night does not happen too often; for Mars for a specific location on Earth it happens (on average) once about every 14 years. So, if you are fortunate to live in the occultation zone and the weather gods cooperate, this upcoming event is one that really should not be missed.

Since Mars will be at opposition when it has its lunar rendezvous, it will be shining at its very brightest for this current apparition. Normally, even a bright star can be quite difficult to see when in such close proximity to the dazzling brilliance of a full moon. Yet, because Mars is as bright as it is (magnitude -1.9; nearly twice as bright as Sirius, the brightest star), this spectacular vanishing act can be watched with just your unaided eye or binoculars, although the very best views will certainly be afforded with a telescope.

Table 1 provides the specific details for 27 selected cities in the United States and Canada. For times with an asterisk (*), the calendar date is Dec. 8.

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Table 1: Local viewing circumstances for the occultation of mars, Dec. 7-8, 2022
Location Time zone Mars disappears Mars reappears
Juneau AKST 6:19 p.m. 6:55 p.m.
Los Angeles PST 6:30 p.m. 7:30 p.m.
San Francisco PST 6:34 p.m. 7:35 p.m.
Seattle PST 6:51 p.m. 7:50 p.m.
Vancouver PST 6:55 p.m. 7:52 p.m.
Tucson MST 7:32 p.m. 8:27 p.m.
Las Vegas MST 7:34 p.m. 8:35 p.m.
Salt Lake City MST 7:41 p.m. 8:46 p.m.
Denver MST 7:44 p.m. 8:48 p.m.
Helena MST 7:51 p.m. 8:56 p.m.
Edmonton MST 8:04 p.m. 9:06 p.m.
Yellowknife MST 8:23 p.m. 9:16 p.m.
Whitehorse MST 8:25 p.m. 8:57 p.m.
Tulsa CST 8:54 p.m. 9:41 p.m.
Kansas City CST 8:56 p.m. 9:52 p.m.
Austin CST 8:57 p.m. 9:12 p.m.
Saskatoon CST 9:03 p.m. 10:10 p.m.
Winnipeg CST 9:05 p.m. 10:16 p.m.
Chicago CST 9:10 p.m. 10:04 a.m.
Memphis CST 9:14 p.m. 9:29 p.m.
Churchill CST 9:22 p.m. 10:31 p.m.
Louisville EST 10:21 p.m. 10:47 p.m.
Toronto EST 10:29 p.m. 11:17 p.m.
Montreal EST 10:40 p.m. 11:29 p.m.
Quebec City EST 10:45 p.m. 11:36 p.m.
Halifax AST 12:15 a.m.* 12:33 a.m.*
Gander NST 12:47 a.m.* 1:37 a.m.*

The above table gives civil times of Mars’ disappearance and reappearance from behind the moon. Both the disappearance and reappearance of the planet, can last anywhere from 40 seconds to over two minutes, depending on whether Mars passes centrally behind the moon (and is covered for an hour or more) or near its lower edge at a slant (and is covered for less than a half hour). Disappearance and reappearance times are for Mars’ center.

Table was adapted from data provided by the International Occultation Timing Association (IOTA) (opens in new tab).

Mars was at its closest proximity to Earth on Dec. 1 at a distance of 50.61 million miles, 81.446 million km, or 4.5 light-minutes. (Image credit: Starry Night Software)

Don’t miss this near miss!

For the rest of North America, this will be an exceedingly close approach of the moon to Mars (called an appulse). The moon, moving around the Earth in an easterly direction at roughly its own diameter each hour will seem to creep slowly toward and ultimately pass just above the ochre planet. Even though the heavily populated Southeast and Eastern United States will miss out on an occultation, Mars will almost command people to look at it, as it slowly appears to glide below the moon.

For places like Huntsville, Knoxville, Philadelphia and New York, Mars will come to within just 1 arc minute of the moon’s limb; they’ll almost seem to touch each other. To the naked eye, Mars will look like an amber jewel on the bottom edge of the moon. From Boston the gap between Mars and the moon’s limb is even smaller: just 0.6 arc minute, roughly equal to the apparent width of two Mars diameters!

After closest approach, the moon will move slowly away from Mars through the balance of the overnight hours of Dec. 7 and Dec. 8.

Table 2 provides the specific details for 15 selected cities in the continental U.S., Puerto Rico and Bermuda.  For times with an asterisk (*), the calendar date is Dec. 8.

Swipe to scroll horizontally
Table 2: Local viewing circumstances for the appulse of the moon and mars, Dec. 7 and Dec. 8, 2022
Location Time zone Closest approach Separation
New Orleans EST 9:11 p.m. 3 arc min.
Huntsville EST 9:23 p.m. 1 arc min.
Miami EST 10:16 p.m. 11 arc min.
Jacksonville EST 10:23 p.m. 7 arc min.
Atlanta EST 10:26 p.m. 3 arc min.
Columbia EST 10:31 p.m. 4 arc min.
Knoxville EST 10:31 p.m. 1 arc min.
Charlotte EST 10:36 p.m. 3 arc min.
Norfolk EST 10:46 p.m. 4 arc min.
Washington EST 10:46 p.m. 2 arc min.
Philadelphia EST 10:51 p.m. 1 arc min.
New York EST 10:56 p.m. 1 arc min.
Boston EST 11:01 p.m. 0.6 arc min.
San Juan AST 11:51 p.m. 23 arc min.
Hamilton AST 12:06 a.m.* 11 arc min.

The above table gives civil times (all a.m.) of Mars’s closest approach to the edge of the moon’s lower limb. Separation between Mars and the moon’s lower edge is given in terms of minutes of arc (the apparent width of the moon on Dec. 7 is 30 arc minutes).

Example: From Jacksonville, closest approach is 10:23 p.m. EST, the separation is listed at 7 arc minutes or fractionally roughly 1/4 of the moon’s width will separate Mars from the moon’s lower edge.

Europe too! And after 2022, your next opportunity

Europeans will also be able to partake in this occultation, although for them this event will occur during the predawn morning hours of Thursday (Dec. 8) with the moon descending the west-northwest sky. For Lisbon, Mars will disappear behind the moon at 4:28 a.m. local time and will reappear at 5:02 a.m. For Dublin it’s 4:55 a.m. and 5:56 a.m. London: 5:00 a.m. and 5:59 a.m. Berlin: 6:01 a.m. and 6:56 a.m. Paris: 6:04 a.m. and 7:02 a.m., and Madrid 6:21 a.m. and 7:07 a.m.

The next favorable occultation of Mars for North America will take place on January 14, 2025. at around 4h UT. The moon will be a waning gibbous about 6 hours past full. Mars comes to opposition just two days later.

Joe Rao serves as an instructor and guest lecturer at New York’s Hayden Planetarium (opens in new tab). He writes about astronomy for Natural History magazine (opens in new tab), the Farmers’ Almanac (opens in new tab) and other publications. Follow us on Twitter @Spacedotcom (opens in new tab) and on Facebook (opens in new tab)

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Palomar Observatory Detects Flash From a Black Hole Swallowing a Star

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Do we have enough astronomers researching the universe?

Photo by Dynamic Wang on Unsplash

This discovery happened earlier this year through an all-sky survey at the Palomar Observatory in California. An all-sky survey is a relatively low cost way of monitoring the whole sky for this exact purpose — to detect and investigate photometric variability. Photometric variability is any change in the perceived brightness of light. So, if we are looking at stars very far away, we can measure their perceived brightness over time, and then record any changes.

This particular detection was in a part of the sky where nothing had been observed before. After detecting the flash, the astronomers from NASA and Caltech posted this discovery to an astronomy newsletter. This discovery over course got the attention of many around the world. You could say it turned heads, or more accurately it turned telescopes. In a matter of days, more telescopes had honed in to collect more data.

“Now, the MIT astronomers along with their collaborators have determined a likely source for the signal. In a study appearing today in Nature Astronomy, the scientists report that the signal, named AT 2022cmc, likely comes from a relativistic jet of matter streaking out from a supermassive black hole at close to the speed of light. They believe the jet is the product of a black hole that suddenly began devouring a nearby star, releasing a huge amount of energy in the process.

Astronomers have observed other such “tidal disruption events,” or TDEs, in which a passing star is torn apart by a black hole’s tidal forces. AT 2022cmc is brighter than any TDE discovered to date. The source is also the farthest TDE ever detected, at some 8.5 billion lights years away — more than halfway across the universe.” — MIT

This is an exciting discovery, but perhaps the most interesting observation is that the black hole’s jet might be pointing directly at Earth. Maybe we have something heading our way? In any case, this discovery illuminates a need to continue to develop more powerful telescopes and grow the number of astronomers in our society.

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Consider the amount of human capital and resources it took to detect and investigate this flash of light. From the relatively low cost all-sky survey to the probably hundreds of researchers that were activated to investigate, this was a sizeable effort. And, there are also opportunity costs to investigating any particular flash of light. There is a lot happening in the universe, and we need to be able to detect and investigate in many areas simultaneously. It is impressive that we coordinated a global network of telescopes to investigate this flash of light. What else could we do with an even more advanced and larger global network of astronomers and telescopes?

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