Science
The moon will 'eclipse' Mars before dawn Tuesday! Here's how to see it. – Space.com
As the waning crescent moon rises in the small hours of the morning of Tuesday, Feb. 18, skywatchers will be preparing for an unusual event. That morning the moon glides in front of orange, starlike planet Mars for viewers in much of central and eastern North America, in what is known as an occultation.
Parts of the western and central U.S. and Canada will be able to view both the disappearance and reappearance of the Red Planet in a dark or twilight sky. However, from western Canada, the Pacific Northwest and northern portions of California and Nevada, only the end of the occultation will be seen, since Mars will already be behind the moon when it rises around 3:30 a.m. local time. On the other hand, across the Eastern U.S., the planet will both disappear and emerge after sunup.
Under reasonably dark skies, this event can be watched over western locations with the naked eye or binoculars, although a telescope will provide the best views. Over the Desert Southwest and parts of the Rocky Mountain States along and east of the Continental Divide, the entire event will occur under a dark sky, but will take place very low in the east-southeast; an open view of the horizon is required. Right now, Mars is relatively faint at magnitude +1.2 and will be dimmed further by its low altitude, but it should not be hard to spot.
Related: The brightest planets in February’s night sky: How to see them (and when)
Near and immediately east (right) of a line extending roughly from Santa Barbara, California to Idaho Falls, Idaho to Havre, Montana, the bright limb of the moon occults the planet when it is still too low to view. But Mars’ reappearance from behind the moon’s dark limb will be much more observable, because the moon will be higher above the horizon and the planet won’t be washed out by the crescent’s bright glare.
Unlike the pinpoint image of a star, which upon interaction with the moon appears to vanish or reappear as if you’ve clicked a switch, the larger apparent size of Mars causes it to disappear or emerge more gradually. About 15 seconds should elapse for the moon to fully cover (or uncover) the tiny disk of Mars after the edges of the two bodies appear to make contact. But the duration will be slightly longer for locations well to the north or south, where the occultation is not nearly central.
Mars currently shows a gibbous disk with an apparent diameter of 5.1 arc seconds. The first speck of light from the Red Planet when it reappears from behind the moon will be at the moon’s dark limb and can be spotted by an observer looking in the right place with a small telescope. Mars will emerge into view as a tiny, brilliant fiery blob — seemingly like a burst of lava from some great lunar volcano.
In order to help observers anticipate where Mars will disappear (behind the moon’s bright limb) and reappear (from behind the moon’s dark limb), the accompanying diagram shows the apparent path of Mars as seen from various cities. The numbers specify the cities as given in this list. For some locations (such as San Francisco, #17), the disappearance will occur before moonrise, so its track on the left is not shown.
More difficult farther east
As one heads east, the occultation will take place after the break of dawn and the advance of morning twilight. Across the northern and central Great Plains, as well as the western half of Oklahoma and Texas, Mars will disappear in a dark sky, but twilight will be well advanced when it reappears. Binoculars or a telescope will be needed to see the emergence from behind the moon’s dark limb. From the Great Lakes, Greater Ohio Valley and the Deep South, Mars will disappear in a twilight sky and reappear after sunrise.
And for New England, upstate New York, Toronto and Montreal, the greater New York City area and New Jersey, Middle Atlantic Coast, Piedmont and Southeast Coast including Florida, the entire occultation will be a daytime affair.
Trying to see the occultation from these regions will prove to be quite a challenge to say the least!
Prior to sunrise, you’ll see Mars sitting less than a couple of degrees to the left of the 24% illuminated lunar crescent. Moving at roughly its own apparent diameter per hour, the moon will appear to gradually creep closer to Mars as they slowly ascend and the background sky turns progressively brighter. With the naked eye alone, you’ll probably lose sight of Mars about a half hour before sunrise, though it still should be readily visible through binoculars and small telescopes. To continue seeing it after sunrise however, will require a very clear (haze-free) day. The surface brightness of Mars (amount of light per square arc second) is about equal to that of the moon.
In the accompanying table, predicted times at 28 cities are given for this “Mars eclipse.” Also included is whether the event in question takes place in a dark sky, at mid-twilight (30 to 60 minutes before sunrise), bright twilight (30 minutes to just a few minutes before sunrise), near sunrise (within a couple of minutes of sunup) and daytime (after sunrise).
For San Francisco and Seattle, where no time is listed under disappearance, that event occurs before moonrise.
Disapearance | Reappearance | |
---|---|---|
Atlanta, Georgia | 7:07 a.m. Daytime | 8:45 a.m. Daytime |
Austin, Texas | 5:46 a.m. Dark sky | 7:09 a.m. Near sunrise |
Boston, Massachusetts | 7:44 a.m. Daytime | 9:10 a.m. Daytime |
Chicago, Illinois | 6:07 a.m. Bright twilight | 7:35 a.m. Daytime |
Denver, Colorado | 4:41 a.m. Dark sky | 6:02 a.m. Mid-twilight |
Gander, Newfoundland, Canada | 9:48 a.m. Daytime | 11:00 a.m. Daytime |
Helena, Montana | 5:57 a.m. Dark sky | |
Houston, Texas | 5:48 a.m. Dark sky | 7:15 a.m. Daytime |
Kansas City, Missouri | 5:52 a.m. Dark sky | 7:02 a.m. Daytime |
Las Vegas, Nevada | 3:36 a.m. Dark sky | 4:40 a.m. Dark sky |
Los Angeles, California | 3:38 a.m. Dark sky | 4:29 a.m. Dark sky |
Memphis, Tennessee | 5:57 a.m. Mid-twilight | 7:30 a.m. Daytime |
Mexico City, Mexico | 6:03 a.m. Dark sky | 6:43 a.m. Bright twilight |
Miami, Florida | 7:15 a.m. Daytime | 8:57 a.m. Daytime |
Monterrey, Mexico | 5:47 a.m. Dark sky | 6:56 a.m. Bright twilight |
Montreal, Quebec, Canada | 7:39 a.m. Daytime | 8:59 a.m. Daytime |
New Orleans, Louisiana | 5:55 a.m. Mid-twilight | 7:29 a.m. Daytime |
New York, New York | 7:36 a.m. Daytime | 9:05 a.m. EST Daytime |
Quebec City, Quebec, Canada | 7:46 a.m. Daytime | 9:03 a.m. Daytime |
Salt Lake City, Utah | 4:37 a.m. Dark sky | 5:51 a.m. Dark sky |
San Francisco, California | 4:30 a.m. Dark sky | |
Seattle, Washington | 4:47 a.m. Dark sky | |
Sioux Falls, South Dakota | 5:53 a.m. Dark sky | 6:18 a.m. Near sunrise |
Toronto, Ontario, Canada | 7:26 a.m. Daytime | 8:50 a.m. Daytime |
Tucson, Arizona | 4:38 a.m. Dark sky | 5:40 a.m. Dark sky |
Tulsa, Oklahoma | 5:49 a.m. Dark sky | 7:17 a.m. Near sunrise |
Washington, D.C. | 7:27 a.m. Daytime | 9:00 a.m. Daytime |
Winnipeg, Manitoba, Canada | 6:02 a.m. Dark sky | 7:18 a.m. Bright twilight |
But wait, there’s more!
For a listing of predicted times for over 700 locations, go to: http://occultations.org/documents/2020/20200218MarsWorld.txt
For a map depicting the region of visibility of this occultation, go to: http://occultations.org/documents/2020/20200218MarsWorldMap.jpg
The turquoise curves show where the disappearance or reappearance occurs at moonrise (left side) or moonset (right side); there is no northern limit as that misses the Earth to the north. The southern limit of the occultation, from which a partial occultation will be visible in a strip about 5 miles wide, crosses the n.e. Pacific Ocean and southern Mexico (white line, event at night), Central America (dark blue line that’s hardly visible, event during morning twilight), and northern S. America and the Atlantic Ocean (red dotted line, event during daylight).
Times and map are courtesy of Mr. David Dunham, International Occultation Timers association.
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.
Science
SpaceX launch marks 300th successful booster landing – Phys.org
SpaceX sent up the 30th launch from the Space Coast for the year on the evening of April 23, a mission that also featured the company’s 300th successful booster recovery.
A Falcon 9 rocket carrying 23 of SpaceX’s Starlink internet satellites blasted off at 6:17 p.m. Eastern time from Cape Canaveral Space Force Station’s Space Launch Complex 40.
The first-stage booster set a milestone of the 300th time a Falcon 9 or Falcon Heavy booster made a successful recovery landing, and the 270th time SpaceX has reflown a booster.
This particular booster made its ninth trip to space, a resume that includes one human spaceflight, Crew-6. It made its latest recovery landing downrange on the droneship Just Read the Instructions in the Atlantic Ocean.
The company’s first successful booster recovery came in December 2015, and it has not had a failed booster landing since February 2021.
The current record holder for flights flew 11 days ago making its 20th trip off the launch pad.
SpaceX has been responsible for all but two of the launches this year from either Kennedy Space Center or Cape Canaveral with United Launch Alliance having launched the other two.
SpaceX could knock out more launches before the end of the month, putting the Space Coast on pace to hit more than 90 by the end of the year, but the rate of launches by SpaceX is also set to pick up for the remainder of the year with some turnaround times at the Cape’s SLC-40 coming in less than three days.
That could amp up frequency so the Space Coast could surpass 100 launches before the end of the year, with the majority coming from SpaceX. It hosted 72 launches in 2023.
More launches from ULA are on tap as well, though, including the May 6 launch atop an Atlas V rocket of the Boeing CST-100 Starliner with a pair of NASA astronauts to the International Space Station.
ULA is also preparing for the second launch ever of its new Vulcan Centaur rocket, which recently received its second Blue Origin BE-4 engine and is just waiting on the payload, Sierra Space’s Dream Chaser spacecraft, to make its way to the Space Coast.
Blue Origin has its own rocket it wants to launch this year as well, with New Glenn making its debut as early as September, according to SLD 45’s range manifest.
2024 Orlando Sentinel. Distributed by Tribune Content Agency, LLC.
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SpaceX launch marks 300th successful booster landing (2024, April 24)
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Science
Wildlife Wednesday: loons are suffering as water clarity diminishes – Canadian Geographic
The common loon, that icon of northern wilderness, is under threat from climate change due to declining water clarity. Published earlier this month in the journal Ecology, a study conducted by biologists from Chapman University and Rensselaer Polytechnic Institute in the U.S. has demonstrated the first clear evidence of an effect of climate change on this species whose distinct call is so tied to the soundscape of Canada’s lakes and wetlands.
Through the course of their research, the scientists found that July rainfall results in reduced July water clarify in loon territories in Northern Wisconsin. In turn, this makes it difficult for adult loons to find and capture their prey — mainly small fish — underwater, meaning they are unable to meet their chicks’ metabolic needs. Undernourished, the chicks face higher mortality rates. The consistent foraging techniques used by loons across their range means this impact is likely echoed wherever they are found — from Alaska to Canada to Iceland.
The researchers used Landsat imagery to find that there has been a 25-year consistent decline in water clarity, and during this period, body weights of adult loon and chicks alike have also declined. With July being the month of most rapid growth in young loons, the study also pinpointed water clarity in July as being the greatest predictor of loon body weight.
One explanation for why heavier rainfall leads to reduced water clarity is the rain might carry dissolved organic matter into lakes from adjacent streams and shoreline areas. Lawn fertilizers, pet waste and septic system leaks may also be to blame.
The researchers, led by Chapman University professor Walter Piper, hope to use these insights to further conservation efforts for this bird Piper describes as both “so beloved and so poorly understood.”
Return of the king
Science
Giant prehistoric salmon had tusk-like teeth for defence, building nests
|
The artwork and publicity materials showcasing a giant salmon that lived five million years ago were ready to go to promote a new exhibit, when the discovery of two fossilized skulls immediately changed what researchers knew about the fish.
Initial fossil discoveries of the 2.7-metre-long salmon in Oregon in the 1970s were incomplete and had led researchers to mistakenly suggest the fish had fang-like teeth.
It was dubbed the “sabre-toothed salmon” and became a kind of mascot for the Museum of Natural and Cultural History at the University of Oregon, says researcher Edward Davis.
But then came discovery of two skulls in 2014.
Davis, a member of the team that found the skulls, says it wasn’t until they got back to the lab that he realized the significance of the discovery that has led to the renaming of the fish in a new, peer-reviewed study.
“There were these two skulls staring at me with sideways teeth,” says Davis, an associate professor in the department of earth sciences at the university.
In that position, the tusk-like teeth could not have been used for biting, he says.
“That was definitely a surprising moment,” says Davis, who serves as director of the Condon Fossil Collection at the university’s Museum of Natural and Cultural History.
“I realized that all of the artwork and all of the publicity materials and bumper stickers and buttons and T-shirts we had just made two months prior, for the new exhibit, were all out of date,” he says with a laugh.
Davis is co-author of the new study in the journal PLOS One, which renames the giant fish the “spike-toothed salmon.”
It says the salmon used the tusk-like spikes for building nests to spawn, and as defence mechanisms against predators and other salmon.
The salmon lived about five million years ago at a time when Earth was transitioning from warmer to relatively cooler conditions, Davis says.
It’s hard to know exactly why the relatives of today’s sockeye went extinct, but Davis says the cooler conditions would have affected the productivity of the Pacific Ocean and the amount of rain feeding rivers that served as their spawning areas.
Another co-author, Brian Sidlauskas, says a fish the size of the spike-toothed salmon must have been targeted by predators such as killer whales or sharks.
“I like to think … it’s almost like a sledgehammer, these salmon swinging their head back and forth in order to fend off things that might want to feast on them,” he says.
Sidlauskas says analysis by the lead author of the paper, Kerin Claeson, found both male and female salmon had the “multi-functional” spike-tooth feature.
“That’s part of our reason for hypothesizing that this tooth is multi-functional … It could easily be for digging out nests,” he says.
“Think about how big the (nest) would have to be for an animal of this size, and then carving it out in what’s probably pretty shallow water; and so having an extra digging tool attached to your head could be really useful.”
Sidlauskas says the giant salmon help researchers understand the boundaries of what’s possible with the evolution of salmon, but they also capture the human imagination and a sense of wonder about what’s possible on Earth.
“I think it helps us value a little more what we do still have, or I hope that it does. That animal is no longer with us, but it is a product of the same biosphere that sustains us.”
This report by The Canadian Press was first published April 24, 2024.
Brenna Owen, The Canadian Press
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