If the Milky Way exists in the biggest cosmic void ever observed, that could solve a puzzling mismatch between ways to measure how fast the universe is expanding.
Observations of 120,000 galaxies bolstering the Milky Way’s loner status were presented by Benjamin Hoscheit June 7 at a meeting of the American Astronomical Society in Austin, Texas. Building on earlier work by his adviser, University of Wisconsin‒Madison astronomer Amy Barger, Hoscheit and Barger measured how the density of galaxies changed with distance from the Milky Way. In agreement with the earlier study, the pair found that the Milky Way has far fewer neighbors than it should. There was a rise in density about 1 billion light-years out, suggesting the Milky Way resides in an abyss about 2 billion light-years wide.
Simulations of how cosmic structures form suggest that most galaxies clump along dense filaments of dark matter, which are separated by vast cosmic voids.
If the Milky Way lives in such a void, it could help explain why the universe seems to be expanding at different rates depending on how it’s measured (SN: 8/6/16, p. 10). Measurements based on the cosmic microwave background, the earliest light in the universe, suggest one rate of expansion, while measurements of nearby supernovas suggest a faster one.
Those supernovas could be feeling an extra gravitational pull from all the matter at the edges of the void, Hoscheit says. The actual expansion rate is probably the slower one measured in the universe’s early light.
“If you don’t account for the void effects, you could mistake this relationship to indicate that there is too much expansion,” Hoscheit says.
Pigs are a step closer to becoming organ donors for people.
Researchers used molecular scissors known as CRISPR/Cas9 to snip embedded viruses out of pig DNA. Removing the viruses — called porcine endogenous retroviruses, or PERVs — creates piglets that can’t pass the viruses on to transplant recipients, geneticist Luhan Yang and colleagues report online August 10 in Science.
Yang, a cofounder of eGenesis in Cambridge, Mass., and colleagues had previously sliced 62 PERVs at a time from pig cells grown in the lab (SN: 11/14/15, p. 6). Many of the embedded viruses are already damaged and can’t make copies of themselves to pass on an infection. So in the new study, the researchers removed just 25 viruses that were still capable of infecting other cells. The team had to overcome several technical hurdles to make PERV-less pig cells that still had the normal number of chromosomes. In a process similar to the one that created Dolly the Sheep (SN: 3/1/97, p. 132), researchers sucked the DNA-containing nuclei from the virus-cleaned cells and injected them into pig eggs. The technique, called somatic cell nuclear transfer, is better known as cloning. Embryos made from the cloned cells were transplanted to sows to develop into piglets.
The process is still not very efficient. Researchers placed 200 to 300 embryos in each of 17 sows. Only 37 piglets were born, and 15 are still living. The oldest are about 4 months old. Such virus-free swine could be a starting point for further genetic manipulations to make pig organs compatible with humans.
Carbondale, Ill., is just a few kilometers north of the point where this year’s total solar eclipse will linger longest — the city will get two minutes and 38 seconds of total darkness when the moon blocks out the sun. And it’s the only city in the United States that will also be in the path of totality when the next total solar eclipse crosses North America, in 2024 (SN: 8/5/17, p. 32). The town is calling itself the Eclipse Crossroads of America. “Having a solar eclipse that goes through the entire continent is rare enough,” says planetary scientist Padma Yanamandra-Fisher of the Space Science Institute’s branch in Rancho Cucamonga, Calif. “Having two in seven years is even more rare. And two going through the same city is rarer still.”
That makes Carbondale the perfect spot to investigate how the sun’s atmosphere, or corona, looks different when solar activity is high versus low.
Every 11 years or so, the sun cycles from periods of high magnetic field activity to low activity and back again. The frequency of easy-to-see features — like sunspots on the sun’s visible surface, solar flares and the larger eruptions of coronal mass ejections — cycles, too. But it has been harder to trace what happens to the corona’s streamers, the long wispy tendrils that give the corona its crownlike appearance and originate from the magnetic field. The corona is normally invisible from Earth, because the bright solar disk washes it out. Even space telescopes that are trained on the sun can’t see the inner part of the corona — they have to block some of it out for their own safety (SN Online: 8/11/17). So solar eclipses are the only time researchers can get a detailed view of what the inner corona, where the streamers are rooted, is up to. Right now, the sun is in a period of exceptionally low activity. Even at the most recent peak in 2014, the sun’s number of flares and sunspots was pathetically wimpy (SN: 11/2/13, p. 22). During the Aug. 21 solar eclipse, solar activity will still be on the decline. But seven years from now during the 2024 eclipse, it will be on the upswing again, nearing its next peak.
Yanamandra-Fisher will be in Carbondale for both events. This year, she’s teaming up with a crowdsourced eclipse project called the Citizen Continental-America Telescope Eclipse experiment. Citizen CATE will place 68 identical telescopes along the eclipse’s path from Oregon to South Carolina.
As part of a series of experiments, Yanamandra-Fisher and her colleagues will measure the number, distribution and extent of streamers in the corona. Observations of the corona during eclipses going back as far as 1867 suggest that streamers vary with solar activity. During low activity, they tend to be more squat and concentrated closer to the sun’s equator. During high activity, they can get more stringy and spread out.
Scientists suspect that’s because as the sun ramps up its activity, its strengthening magnetic field lets the streamers stretch farther out into space. The sun’s equatorial magnetic field also splits to straddle the equator rather than encircle it. That allows streamers to spread toward the poles and occupy new space.
Although physicists have been studying the corona’s changes for 150 years, that’s still only a dozen or so solar cycles’ worth of data. There is plenty of room for new observations to help decipher the corona’s mysteries. And Yanamandra-Fisher’s group might be the first to collect data from the same point on Earth.
“This is pure science that can be done only during an eclipse,” Yanamandra-Fisher says. “I want to see how the corona changes.”
On Jupiter, lightning jerks and jolts a lot like it does on Earth.
Jovian lightning emits radio wave pulses that are typically separated by about one millisecond, researchers report May 23 in Nature Communications. The energetic prestissimo, the scientists say, is a sign that the gas giant’s lightning propagates in pulses, at a pace comparable to that of the bolts that cavort through our own planet’s thunderclouds. The similarities between the two world’s electrical phenomena could have implications for the search for alien life. Arcs of lightning on both worlds appear to move somewhat like a winded hiker going up a mountain, pausing after each step to catch their breath, says Ivana Kolmašová, an atmospheric physicist at the Czech Academy of Sciences in Prague. “One step, another step, then another step … and so on.”
Here on Earth, lightning forms as turbulent winds within thunderclouds cause many ice crystals and water droplets to rub together, become charged and then move to opposite sides of the clouds, progressively generating static electrical charges. When the charges grow big enough to overcome the air’s ability to insulate them, electrons are released — the lightning takes its first step. From there, the surging electrons will repeatedly ionize the air and rush into it, lurching the bolt forward at an average of hundreds of thousands of meters per second.
Scientists have suggested that superbolts observed in Jovian clouds might also form by collisions between ice crystals and water droplets (SN: 8/5/20). But no one knew whether the alien bolts extended and branched in increments, as they do on Earth, or if they took some other form.
For the new study, Kolmašová and her colleagues used five years of radio wave data collected by NASA’s Juno spacecraft (SN: 12/15/22). Analyzing hundreds of thousands of radio wave snapshots, the team found radio wave emissions from Jovian lightning appeared to pulse at a rate comparable to that of Earth’s intracloud lightning — arcs of electricity that never strike ground.
If bolts extend through Jupiter’s water clouds at a similar velocity as they do in Earth’s clouds, then Jovian lightning might branch and extend in steps that are hundreds to thousands of meters long. That’s comparable in length to the jolted strides of Earth’s intracloud lightning, the researchers say.
“That’s a perfectly reasonable explanation,” says atmospheric physicist Richard Sonnenfeld of the New Mexico Institute of Mining and Technology in Socorro, who wasn’t involved in the study. Alternatively, he says, the signals could be produced as pulses of electrical current propagate back and forth along tendrils of lightning that have already formed, rather than from the stop-and-go advancements of a new bolt. On Earth, such currents cause some bolts to appear to flicker.
But stop and go seems like a sound interpretation, says atmospheric physicist Yoav Yair of Reichman University in Herzliya, Israel. Kolmašová and her colleagues “show that if you’re discharging a cloud … the physics remains basically the same [on Jupiter as on Earth], and the current will behave the same.”
If that universality is real, it could have implications for the search for life elsewhere. Experiments have shown that lightning strikes on Earth could have smelted some of the chemical ingredients needed to form the building blocks of life (SN: 3/16/21). If lightning is discharging in a similar way on alien worlds, Yair says, then it could be producing similar ingredients in those places too.
Olympic gold-medal winning gymnast Suni Lee said she was the victim of a racist attack in October.
Lee told PopSugar that when she was out with friends in Los Angeles one night, a group speeding by in a car yelled racial slurs and that one passenger in the car sprayed her in the arm with pepper spray as the car drove off. "I was so mad, but there was nothing I could do or control because they skirted off," she told PopSugar. "I didn't do anything to them, and having the reputation, it's so hard because I didn't want to do anything that could get me into trouble. I just let it happen."
Lee, a Hmong American, was with friends, who were all also of Asian descent. She said the group used the term "ching chong" and told the group to "go back to where they came from."
Back in July, Lee became the first Hmong American to represent the United States in the Olympics. She told PopSugar that she has a hard time understanding the hate crimes against Asian Americans, and that while it is difficult to speak about racial injustice, she knows the importance her voice carries.
Stop AAPI Hate reported in August that there have been 9,081 hate incidents since March 19, 2020, and that the number spiked from 6,603 to 9,081 during the period between April and June 2021.
The report stated that there were 4,548 hate incidents in 2020 and 4,533 in 2021. It found that 63.7 percent of the cases were verbal harassment, 16.5 percent were shunning, 13.7 percent were physical assault, 11 percent were civil rights violations and 8.3 percent were online harassment.
The Week 12 College Football Playoff rankings were easily adjustable for the selection committee. But they also set up to be a potentially chaotic final weekend of football.
Only one top-10 team in the most recent set of rankings lost on Saturday. That would be Oklahoma, a team the committee clearly didn't value in the first two sets of rankings, considering the Sooners' position at No. 8 overall in each of those weeks. The top seven teams remained the same following their loss, with Notre Dame, Oklahoma State and Wake Forest moving up to fill in the Sooners' spot. A looming concern for this committee is what will happen if each of the one-loss Power 5 favorites win out the rest of the season. That could create a logjam of Oregon, Ohio State/Michigan/Michigan State and Oklahoma State/Oklahoma. That's to say nothing of the SEC, which could presumably lock up two spots should Alabama beat Georgia in the SEC championship.
Then there's the question of a potentially undefeated Cincinnati team, which if left out would join UCF as a twice-undefeated Group of 5 team that never got a chance to compete for a title.
There's still plenty of football left to be played, including the two Michigan teams vs. Ohio State in the Big Ten; Alabama taking on two ranked teams in the last three weeks of the season; Bedlam; and a not-insignificant end to the season for Cincy, which plays a ranked team in Houston.
It's all shaping up to be a wild, fun and potentially chaotic stretch to end the season. Best take a deep breath while you're still able. Until then, here's the latest top 25 rankings from Week 12: College Football Playoff rankings 2021 Who are the top four CFP teams of third CFP poll of 2021? Ranking Team Record 1 Georgia 10-0 2 Alabama 9-1 3 Oregon 9-1 4 Ohio State 9-1 Who are the first two teams out of third CFP poll of 2021? Ranking Team Record 5 Cincinnati 10-0 6 Michigan 9-1 CFP top 25 rankings from third CFP poll of 2021 Rank Team Record 1 Georgia 10-0 2 Alabama 9-1 3 Oregon 9-1 4 Ohio State 9-1 5 Cincinnati 10-0 6 Michigan 9-1 7 Michigan State 9-1 8 Notre Dame 9-1 9 Oklahoma State 9-1 10 Wake Forest 9-1 11 Baylor 8-2 12 Ole Miss 8-2 13 Oklahoma 9-1 14 BYU 8-2 15 Wisconsin 7-3 16 Texas A&M 7-3 17 Iowa 8-2 18 Pitt 8-2 19 San Diego State 9-1 20 N.C. State 7-3 21 Arkansas 7-3 22 UTSA 10-0 23 Utah 7-3 24 Houston 9-1 25 Mississippi State 6-4
