NASA Astronomy Picture of the Day

Sep 22, 2023

Cosmos in Reflection

During the day, over 12,000 large mirrors reflect sunlight at the 100-megawatt, molten-salt, solar thermal power plant at the western edge of the Gobi desert near Dunhuang, Gansu Province, China. Individual mirror panels turn to track the sun like sunflowers. They conspire to act as a single super mirror reflecting the sunlight toward a fixed position, the power station's central tower. During the night the mirrors stand motionless though. They reflect the light of the countless distant stars, clusters and nebulae of the Milky Way and beyond. This sci-fi night skyscape was created with a camera fixed to a tripod near the edge of the giant mirror matrix on September 15. The camera's combined sequence of digital exposures captures concentric arcs of celestial star trails through the night with star trails in surreal mirrored reflection.

https://apod.nasa.gov/apod/ap230922.html

>>19597367

Sep 23, 2023

Afternoon Analemma

An analemma is that figure-8 curve you get when you mark the position of the Sun at the same time each day for one year. To make this one, a 4x5 pinhole camera was set up looking north in southern New Zealand skies. The shutter was briefly opened each clear day in the afternoon at 4pm local time exposing the same photosensitized glass plate for the year spanning September 23, 2022 to September 19, 2023. On two days, the winter and summer solstices, the shutter was opened again 15 minutes after the main exposure and remained open until sunset to create the sun trails at the bottom and top of the curve. The equinox dates correspond to positions in the middle of the curve, not the crossover point. Of course, the curve itself is inverted compared to an analemma traced from the northern hemisphere. And while fall begins today at the Autumnal Equinox for the northern hemisphere, it's the Spring Equinox in the south.

https://apod.nasa.gov/apod/astropix.html?

476,000-Year-Old Wooden Structure Unearthed in Zambia

Sep 20, 2023

Archaeologists have found an ancient wooden structure at the archaeological site of Kalambo Falls in Zambia. This structure — dated to about 476,000 years ago — has no known parallels in the African or Eurasian Paleolithic and may represent the earliest use of wood in construction.

Wooden artifacts rarely survive from the Early Paleolithic as they require exceptional conditions for preservation.

Therefore, archaeologists have limited information about when and how hominins used this basic raw material or how Paleolithic humans structured their environments.

Our find has changed how I think about our early ancestors,” said University of Liverpool’s Professor Larry Barham.

“Forget the label ‘Stone Age,’ look at what these people were doing: they made something new, and large, from wood.”

“They used their intelligence, imagination, and skills to create something they’d never seen before, something that had never previously existed.”

“They transformed their surroundings to make life easier, even if it was only by making a platform to sit on by the river to do their daily chores. These folks were more like us than we thought.”

Professor Barham and colleagues discovered an ancient wooden structure at the archaeological site of Kalambo Falls, which lies above a 235-m (772-foot) waterfall on the border of Zambia with the Rukwa Region of Tanzania at the edge of Lake Tanganyika.

The structure includes two preserved interlocking logs joined transversely by an intentionally cut notch. The upper log had been shaped, and tool marks were found on both logs.

The logs could have been used to construct a raised platform, walkway or foundation for dwellings in the periodically wet floodplain.

“This discovery challenges the prevailing view that Stone Age humans were nomadic,” the researchers said.

“At Kalambo Falls these humans not only had a perennial source of water, but the forest around them provided enough food to enable them to settle and make structures.”

They used new luminescence dating techniques, which reveal the last time minerals in the sand surrounding the finds were exposed to sunlight, to determine their age.

“At this great age, putting a date on finds is very challenging and we used luminescence dating to do this,” said Aberystwyth University’s Professor Geoff Duller.

“These new dating methods have far reaching implications — allowing us to date much further back in time, to piece together sites that give us a glimpse into human evolution.”

At Kalambo, the scientists also recovered four wood tools from 390,000 to 324,000 years ago, including a wedge, digging stick, cut log and notched branch.

“The finds show an unexpected early diversity of forms and the capacity to shape tree trunks into large combined structures,” the authors concluded.

“These new data not only extend the age range of woodworking in Africa but expand our understanding of the technical cognition of early hominins, forcing re-examination of the use of trees in the history of technology.”

https://www.sci.news/archaeology/wooden-structure-kalambo-falls-zambia-12283.html

https://www.nature.com/articles/s41586-023-06557-9

Congressman Shares 'Very Elusive' NASA Remarks from UFO Meeting

9/21/23 AT 6:22 PM EDT

Tennessee Representative Tim Burchett described the House Oversight Committee's meeting with members of the National Aeronautics and Space Administration (NASA) as "elusive" as lawmakers continue to push for answers on unidentified flying objects (UFOs).

House members were briefed Thursday on NASA's independent report regarding UFOs, also known as unidentified aerial phenomena (UAP), that was released earlier this month. Congressmen on both sides of the aisle have demanded greater transparency from the Pentagon regarding the issue of UAP after hearing from three witnesses in late July who testified about their experiences with unexplainable phenomena while working for the Defense Department.

But Burchett, a Republican who was one of the leading voices ahead of July's hearing to push for additional Congressional oversight on the issue of UAP, said that he left Thursday's meeting with NASA "disappointed," telling his followers in a video message to X, formerly Twitter, that the report "didn't say a whole lot to me."

"My colleague [Alabama Representative] Gary Palmer asked about classified stuff at NASA, and they said, 'We don't have anything classified,'" Burchett said regarding the meeting.

According to the congressman's video, when pressed further about the issue of classified information, the representatives from NASA gave a "very elusive" response.

"And so, what I think they've done is, they sent these two folks in here, like the Pentagon did, that have very little knowledge of the issue," Burchett continued. "So they can say they can hold up their hand before Congress and swear that they know nothing about the issue, and it doesn't exist."

Burchett said that he also pressed the NASA representatives about the testimonies that came out during July's hearing, as well as videos of UAP that have been declassified and shared with the public.

"So anyway, didn't get a lot from that, and I'm a little disappointed," the congressman concluded.

"We're probably going to have to get some more people from the Pentagon in there to tell us what exactly is going on."

"I just want the truth," he added. "Give me the facts."

Newsweek reached out to Dr. Daniel Evans, assistant deputy associate administrator for research at NASA who served as the designated federal official on the agency's UAP report, for comment Thursday evening.

NASA's report was compiled by a team of 16 experts and was intended to look at how the agency could use data to better understand UAP. The group concluded in its review that there was no "conclusive evidence" that suggested UAP is the source of extraterrestrial origins and suggested that the agency should play a "prominent role" in working to better understand the phenomena.

The report also called for greater transparency around UAP and suggested that the agency could help remove the negative stigma that witnesses feel when reporting experiences.

"NASA's long-standing public trust, which is essential for communicating findings about these phenomena to the public, is also crucial for destigmatizing UAP reporting," the report read. "The scientific processes used by NASA encourage critical thinking and skepticism; within this framework, there should be no credulous acceptance of unlikely reports with unlikely explanations."

https://www.newsweek.com/congressman-shares-very-elusive-nasa-remarks-ufo-meeting-1829025

Evidence of mysterious 'recurring nova' that could reappear in 2024 found in medieval manuscript from 1217

Sep 20, 2023

In 1217, a German monk looked to the starry southwest sky and noticed a normally faint star shining with unusual intensity. It continued to blaze for several days. Abbott Burchard, the leader of Ursberg Abbey at the time, recorded the sight in that year's chronicle. "A wonderful sign was seen," he wrote, adding that the mysterious object in the constellation Corona Borealis "shone with great light" for "many days."

This medieval manuscript may have been the first record of a rare space phenomenon called a recurrent nova — a dead star siphoning matter from a larger companion, triggering repeated flares of light at regular intervals. According to new research, the "wonderful" star in question may be T CrB, which sits in the constellation Corona Borealis and dramatically increases in brightness for about a week every 80 years. But it has been scientifically documented only twice — once in 1866, and again in 1946. (The star’s next long-awaited flare-up is expected in 2024).

In a preprint paper, available on arXiv.org, astronomer Bradley E. Schaefer of Louisiana State University argues that Burchard's record and another chronicle from 1787 constitute the first known sightings of the T CrB nova.

But how can we be sure that Burchard had spotted T CrB and not some other celestial phenomenon, such as a one-off supernova or a comet? Schaefer ruled out the possibility of a supernova pretty much right away, on the grounds that if such a violent event — which occurs when a massive star dies in a dramatic explosion — had occurred that recently, it would have left behind remnants that would be clearly visible today. (The Crab Nebula, for example, is thought to be the remnant of a 1,000-year-old supernova and is visible to most telescopes today.)

Considering nobody has observed supernova remnants in the Corona Borealis star formation, it is unlikely that this kind of massive stellar explosion was the culprit. Similarly, Schaefer eliminated a bright planet from the list of suspects, as no planets visible to the naked eye wander through that region of the sky.

The possibility that the event was a comet is a bit trickier to disprove. A comet was visible in the sky earlier that year, according to a chronicle from the St. Stephani monastery in Greece. However, most monks of the time were familiar with comets, which were considered portents of doom. It's unlikely that Burchard would have recorded a comet as something "wonderful," or failed to mention its tail, Schaefer contends.

The 1787 sighting was recorded by English reverend and astronomer Francis Wollaston. This account describes nova-like behavior from a star whose coordinates match T CrB's position in the sky almost exactly. While Wollaston identified this star using a name from famed astronomer William Herschel's catalog, Schaefer believes its true identity is T CrB.

Scientists will be ready for the nova's next expected flare in late 2024. When it comes, modern astronomers will add it to a centuries-long list of past records. In the meantime, researchers will continue digging through old archives to study T CrB's recorded history. Hopefully, such activity will allow them to make more accurate predictions about the star's behavior in the future.

https://www.space.com/evidence-medieval-manuscript-recurring-nova-reappear-2024