From Harvard Astronomy via Science Alert(AU): “Origins of Mysterious Interstellar Visitor ‘Oumuamua May Finally Be Explained”

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From Harvard Astronomy



Science Alert(AU)

17 MARCH 2021

The origin and identity of a massive space object that careened past Earth in 2017 have remained a mystery ever since.

The object, called ‘Oumuamua – a Hawaiian name meaning “scout” or “messenger” – traveled on a trajectory that strongly suggested it came from another star system. That made it the first interstellar object ever detected.

Artist’s impression of ‘Oumuamua. Credit: M. Kornmesser/European Southern Observatory(EU)/ .

But what was it? A few researchers, including Harvard University astronomer Avi Loeb, posited the object was an alien spacecraft. Others suggested it was an asteroid, or perhaps an interstellar comet.

Now, a pair of papers published in an American Geophysical Union journal offers another theory: that ‘Oumuamua was shrapnel from a tiny planet in a different Solar System.

JGR PLanets

JGR PLanets

“We’ve probably resolved the mystery of what ‘Oumuamua is, and we can reasonably identify it as a chunk of an ‘exo-Pluto,’ a Pluto-like planet in another Solar System,” Steven Desch, an astrophysicist at Arizona State University(US) and a co-author of the new study, said in a press release.

A planetary fragment made of frozen nitrogen

Desch and his coauthors think that half a billion years ago, a space object struck ‘Oumuamua’s parent planet. That sent ‘Oumuamua careening towards our Solar System.

Once it neared the Sun, their thinking goes, ‘Oumuamua sped up as Sunlight vaporized its icy body. Comets follow a similar movement pattern, known as the “rocket effect”.

Because ‘Oumuamua’s makeup is unknown, the researchers calculated what kinds of ice would sublimate (change from solid to gas) at a rate that could account for ‘Oumuamua’s rocket effect. They concluded that the object is likely made of nitrogen ice, like the surface of Pluto and Neptune’s moon Triton.

As it got approached our Solar System – and therefore the Sun – ‘Oumuamua started sloughing off frozen nitrogen layers. The object entered our Solar System in 1995, though we didn’t realize it at the time, then subsequently lost 95 percent of its mass and melted away to a sliver, according to the study authors.

It’s a comet. It’s an asteroid. Nope, it’s neither.

By the time astronomers became aware of ‘Oumuamua’s existence in 2017, it was already zipping away from Earth at 315,431 km/h (196,000 mph). So they had only a few weeks to study the strange, skyscraper-sized object.

Several telescopes on the ground and one in space took limited observations as the object flew away, but astronomers were unable to examine it in full. ‘Oumuamua is now too far away and too dim to observe further with existing technologies.

The limited nature of the information gathered left room for scientists to offer guesses about what the object might be and where it came from. ‘Oumuamua was initially classified as a comet, but it didn’t appear to be made of ice, and it didn’t emit gases as a comet would.

‘Oumuamua’s spin, speed, and trajectory couldn’t be explained by gravity alone, which suggested it was not an asteroid either. And the object’s shape and profile – it’s about one-quarter of a mile long but only 34.75 meters (114 feet) wide – doesn’t match that of any comet or asteroid observed before.

According to the authors of the new study, however, ‘Oumuamua’s frozen-nitrogen composition could explain that shape.

“As the outer layers of nitrogen ice evaporated, the shape of the body would have become progressively more flattened, just like a bar of soap does as the outer layers get rubbed off through use,” Alan Jackson, another study co-author, said in the release.

Some astronomers still think it was an alien ship.

Unlike most space rocks, ‘Oumuamua seemed to be accelerating, rather than slowing down, in telescope observations.

That is in part why Loeb thinks ‘Oumuamua was an alien spacecraft. In a book he published in January, titled Extraterrestrial: The First Sign of Intelligent Life Beyond Earth, Loeb describes ‘Oumuamua as a defunct piece of alien technology.

“The object has anomalies that merit some attention – things that do not line up in the ways we expected,” he told Insider in December.

“Other people say, ‘Lets shove those anomalies under the rug of conservatism.’ I have a problem with that because when something doesn’t line up, you should say it.”

Still, a 2019 study from an international group of astronomers analyzed all the ‘Oumuamua data available and concluded that Loeb’s theory was unlikely.

“We find no compelling evidence to favor an alien explanation for ‘Oumuamua,” the astronomers wrote.

Matthew Knight, a University of Maryland(US) astronomer who co-wrote the study, put it this way: “This thing is weird and admittedly hard to explain, but that doesn’t exclude other natural phenomena that could explain it.”

See the full article here .


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Although the Department of Astronomy came into existence in 1931, the first chair, Donald Menzel, wasn’t appointed until 1945. Menzel was subsequently named Director of the Harvard College Observatory(US) in 1952 and immediately set about to encourage the Smithsonian Astrophysical Observatory (SAO) to relocate to Cambridge, which it did in 1955.

Fred Whipple was appointed as Professor of Astronomy in 1950 and was the department’s second chair. In 1955 he assumed directorship of the SAO in its new location. In 1956 Cecilia Payne-Gaposchkin became the first woman to be promoted to full professor from within the Faculty of Arts and Sciences and soon after was appointed the third chair, making her the first woman to head a department at Harvard University.

George Field formalized the interactions between the two organizations by creating an administrative umbrella organization named the Harvard-Smithsonian Center for Astrophysics(US). The Department of Astronomy, under a Chair, continues as an autonomous unit under the direction of the Harvard University Faculty of Arts of Sciences but is housed at the CfA.

The complement of approximately 60 PhD students, 25 undergraduate students and over 100 post-doctoral researchers enjoy access to the remarkable resources provided by both Harvard and Smithsonian faculties and facilities.

Harvard is the oldest institution of higher education in the United States, established in 1636 by vote of the Great and General Court of the Massachusetts Bay Colony. It was named after the College’s first benefactor, the young minister John Harvard of Charlestown, who upon his death in 1638 left his library and half his estate to the institution. A statue of John Harvard stands today in front of University Hall in Harvard Yard, and is perhaps the University’s best known landmark.

Harvard University has 12 degree-granting Schools in addition to the Radcliffe Institute for Advanced Study. The University has grown from nine students with a single master to an enrollment of more than 20,000 degree candidates including undergraduate, graduate, and professional students. There are more than 360,000 living alumni in the U.S. and over 190 other countries.

Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Established in 1636 and named for its first benefactor, clergyman John Harvard, Harvard is the oldest institution of higher learning in the United States and among the most prestigious in the world.

The Massachusetts colonial legislature, the General Court, authorized Harvard’s founding. In its early years, Harvard College primarily trained Congregational and Unitarian clergy, although it has never been formally affiliated with any denomination. Its curriculum and student body were gradually secularized during the 18th century, and by the 19th century, Harvard had emerged as the central cultural establishment among the Boston elite. Following the American Civil War, President Charles William Eliot’s long tenure (1869–1909) transformed the college and affiliated professional schools into a modern research university; Harvard became a founding member of the Association of American Universities in 1900.[10] James B. Conant led the university through the Great Depression and World War II; he liberalized admissions after the war.

The university is composed of ten academic faculties plus the Radcliffe Institute for Advanced Study. Arts and Sciences offers study in a wide range of academic disciplines for undergraduates and for graduates, while the other faculties offer only graduate degrees, mostly professional. Harvard has three main campuses: the 209-acre (85 ha) Cambridge campus centered on Harvard Yard; an adjoining campus immediately across the Charles River in the Allston neighborhood of Boston; and the medical campus in Boston’s Longwood Medical Area. Harvard’s endowment is valued at $41.9 billion, making it the largest of any academic institution. Endowment income helps enable the undergraduate college to admit students regardless of financial need and provide generous financial aid with no loans The Harvard Library is the world’s largest academic library system, comprising 79 individual libraries holding about 20.4 million items.

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Harvard was established in 1636 by vote of the Great and General Court of the Massachusetts Bay Colony. In 1638, it acquired British North America’s first known printing press. In 1639, it was named Harvard College after deceased clergyman John Harvard, an alumnus of the University of Cambridge(UK) who had left the school £779 and his library of some 400 volumes.[22] The charter creating the Harvard Corporation was granted in 1650.

A 1643 publication gave the school’s purpose as “to advance learning and perpetuate it to posterity, dreading to leave an illiterate ministry to the churches when our present ministers shall lie in the dust.” It trained many Puritan ministers in its early years and offered a classic curriculum based on the English university model—many leaders in the colony had attended the University of Cambridge—but conformed to the tenets of Puritanism. Harvard has never affiliated with any particular denomination, though many of its earliest graduates went on to become clergymen in Congregational and Unitarian churches.

Increase Mather served as president from 1681 to 1701. In 1708, John Leverett became the first president who was not also a clergyman, marking a turning of the college away from Puritanism and toward intellectual independence.

19th century

In the 19th century, Enlightenment ideas of reason and free will were widespread among Congregational ministers, putting those ministers and their congregations in tension with more traditionalist, Calvinist parties. When Hollis Professor of Divinity David Tappan died in 1803 and President Joseph Willard died a year later, a struggle broke out over their replacements. Henry Ware was elected to the Hollis chair in 1805, and the liberal Samuel Webber was appointed to the presidency two years later, signaling the shift from the dominance of traditional ideas at Harvard to the dominance of liberal, Arminian ideas.

Charles William Eliot, president 1869–1909, eliminated the favored position of Christianity from the curriculum while opening it to student self-direction. Though Eliot was the crucial figure in the secularization of American higher education, he was motivated not by a desire to secularize education but by Transcendentalist Unitarian convictions influenced by William Ellery Channing and Ralph Waldo Emerson.

20th century

In the 20th century, Harvard’s reputation grew as a burgeoning endowment and prominent professors expanded the university’s scope. Rapid enrollment growth continued as new graduate schools were begun and the undergraduate college expanded. Radcliffe College, established in 1879 as the female counterpart of Harvard College, became one of the most prominent schools for women in the United States. Harvard became a founding member of the Association of American Universities in 1900.

The student body in the early decades of the century was predominantly “old-stock, high-status Protestants, especially Episcopalians, Congregationalists, and Presbyterians.” A 1923 proposal by President A. Lawrence Lowell that Jews be limited to 15% of undergraduates was rejected, but Lowell did ban blacks from freshman dormitories.

President James B. Conant reinvigorated creative scholarship to guarantee Harvard’s preeminence among research institutions. He saw higher education as a vehicle of opportunity for the talented rather than an entitlement for the wealthy, so Conant devised programs to identify, recruit, and support talented youth. In 1943, he asked the faculty to make a definitive statement about what general education ought to be, at the secondary as well as at the college level. The resulting Report, published in 1945, was one of the most influential manifestos in 20th century American education.

Between 1945 and 1960, admissions were opened up to bring in a more diverse group of students. No longer drawing mostly from select New England prep schools, the undergraduate college became accessible to striving middle class students from public schools; many more Jews and Catholics were admitted, but few blacks, Hispanics, or Asians. Throughout the rest of the 20th century, Harvard became more diverse.

Harvard’s graduate schools began admitting women in small numbers in the late 19th century. During World War II, students at Radcliffe College (which since 1879 had been paying Harvard professors to repeat their lectures for women) began attending Harvard classes alongside men. Women were first admitted to the medical school in 1945. Since 1971, Harvard has controlled essentially all aspects of undergraduate admission, instruction, and housing for Radcliffe women. In 1999, Radcliffe was formally merged into Harvard.

21st century

Drew Gilpin Faust, previously the dean of the Radcliffe Institute for Advanced Study, became Harvard’s first woman president on July 1, 2007. She was succeeded by Lawrence Bacow on July 1, 2018.