Month: March 2023

Enlarge / Asian woman with protective face mask using smartphone while commuting in the urban bridge in city against crowd of people (credit: d3sign via Getty Images)

On March 28, 2020, as COVID-19 cases began to shut down public life in much of the United States, then-Surgeon General Jerome Adams issued an advisory on Twitter: The general public should not wear masks. “There is scant or conflicting evidence they benefit individual wearers in a meaningful way,” he wrote.

Adams’ advice was in line with messages from other US officials and the World Health Organization. Days later, though, US public health leaders shifted course. Mask-wearing was soon a pandemic-control strategy worldwide, but whether this strategy succeeded is now a matter of heated debate—particularly after a major new analysis, released in January, seemed to conclude that masks remain an unproven strategy for curbing transmission of COVID-19 and other respiratory viruses.

“There’s still no evidence that masks are effective during a pandemic,” the study’s lead author, physician, and epidemiologist Tom Jefferson, recently told an interviewer.

Enlarge / The tattered shell of the first recorded supernova (Sn185) was captured by the Dark Energy Camera. This image covers an impressive 45 arcminutes in the sky—a rare view of the entirety of this supernova remnant. (credit: CTIO/NOIRLab/DOE/NSF)

In early December 185 CE, Chinese astronomers recorded a bright "guest star" in the night sky that shone for eight months in the direction of Alpha Centauri before fading away—most likely the earliest recorded supernova in the historical record. The image above gives us a rare glimpse of the entire tattered remnant of that long-ago explosion, as captured by the Dark Energy Camera (DECam), mounted on the four-meter telescope at the Cerro Tololo Inter-American Observatory in the Andes in Chile. DECam has been operating since 2012, and while it was originally designed to be part of the ongoing Dark Energy Survey, it's also available for other astronomers to use in their research. This new wide-view perspective of the remains of SN 185 should help astronomers learn even more about stellar evolution.

As we've written previously, there are two types of known supernovas, depending on the mass of the original star. An iron-core collapse supernova occurs with massive stars (greater than 10 solar masses), which collapse so violently that it causes a huge, catastrophic explosion. The temperatures and pressures become so high that the carbon in the star's core fuses. This halts the core's collapse, at least temporarily, and this process continues, over and over, with progressively heavier atomic nuclei. When the fuel finally runs out entirely, the (by then) iron core collapses into a black hole or a neutron star.

Then there is a Type Ia supernova. Smaller stars (up to about eight solar masses) gradually cool to become dense cores of ash known as white dwarfs. If a white dwarf that has run out of nuclear fuel is part of a binary system, it can siphon off matter from its partner, adding to its mass until its core reaches high enough temperatures for carbon fusion to occur. These are the brightest supernovae, and they also shine with a remarkably consistent peak velocity, making them invaluable "standard candles" for astronomers to determine cosmic distances.

Enlarge / Hughes Memorial Auditorium, where the outpouring event was hosted, on Asbury University's campus in Wilmore, Kentucky. (credit: Asbury University)

The Centers for Disease Control and Prevention on Friday issued a health alert for doctors and health officials to be on the lookout for measles cases after a person with a confirmed, contagious case attended a massive religious event in Kentucky last month, potentially exposing an estimated 20,000 people to one of the most infectious viruses on the planet.

The event was a spontaneous "outpouring" at Asbury University, which drew tens of thousands of worshippers to the small, private Christian institution in Wilmore from February 8 to 23. Attendees came from around Kentucky, other US states, and other countries.

A case of measles was confirmed in an unvaccinated person who had recently traveled out of the country before attending Asbury University's outpouring. The person was at the event from February 17 to 18, the CDC reported. The university added that the person attended before developing symptoms, suggesting the person did not know they were infected. But the CDC notes that people with measles are contagious four days before measles' telltale rash develops, and state health officials said the person was contagious while they were in attendance.