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COVID-19 Lockdowns Caused Cleaner Air – And Warmed the Planet – SciTechDaily

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Research shows reductions in aerosol emissions had slight, temporary warming impact.

The lockdowns and reduced societal activity related to the COVID-19 pandemic affected emissions of pollutants in ways that slightly warmed the planet for several months last year, according to a new study by the National Center for Atmospheric Research (NCAR).

The counterintuitive finding highlights the influence of airborne particles, or aerosols, that block incoming sunlight. When emissions of aerosols dropped last spring, more of the Sun’s warmth reached the planet, especially in heavily industrialized nations, such as the United States and Russia, that normally pump high amounts of aerosols into the atmosphere.

“There was a big decline in emissions from the most polluting industries, and that had immediate, short-term effects on temperatures,” said NCAR scientist Andrew Gettelman, the study’s lead author. “Pollution cools the planet, so it makes sense that pollution reductions would warm the planet.”

Temperatures over parts of Earth’s land surface last spring were about 0.2-0.5 degrees Fahrenheit (0.1-0.3 degrees Celsius) warmer than would have been expected with prevailing weather conditions, the study found. The effect was most pronounced in regions that normally are associated with substantial emissions of aerosols, with the warming reaching about 0.7 degrees F (0.37 C) over much of the United States and Russia.

The new study highlights the complex and often conflicting influences of different types of emissions from power plants, motor vehicles, industrial facilities, and other sources. While aerosols tend to brighten clouds and reflect heat from the Sun back into space, carbon dioxide and other greenhouse gases have the opposite effect, trapping heat near the planet’s surface and elevating temperatures.

Despite the short-term warming effects, Gettelman emphasized that the long-term impact of the pandemic may be to slightly slow climate change because of reduced emissions of carbon dioxide, which lingers in the atmosphere for decades and has a more gradual influence on climate. In contrast, aerosols – the focus of the new study – have a more immediate impact that fades away within a few years.

The study was published in Geophysical Research Letters. It was funded in part by the National Science Foundation, NCAR’s sponsor. In addition to NCAR scientists, the study was co-authored by scientists at Oxford University, Imperial College, and the University of Leeds.

Teasing out the impacts

Although scientists have long been able to quantify the warming impacts of carbon dioxide, the climatic influence of various types of aerosols – including sulfates, nitrates, black carbon, and dust – has been more difficult to pin down. One of the major challenges for projecting the extent of future climate change is estimating the extent to which society will continue to emit aerosols in the future and the influence of the different types of aerosols on clouds and temperature.

To conduct the research, Gettelman and his co-authors used two of the world’s leading climate models: the NCAR-based Community Earth System Model and a model known as ECHAM-HAMMOZ, which was developed by a consortium of European nations. They ran simulations on both models, adjusting emissions of aerosols and incorporating actual meteorological conditions in 2020, such as winds.

This approach enabled them to identify the impact of reduced emissions on temperature changes that were too small to tease out in actual observations, where they could be obscured by the variability in atmospheric conditions.

The results showed that the warming effect was strongest in the mid and upper latitudes of the Northern Hemisphere. The effect was mixed in the tropics and comparatively minor in much of the Southern Hemisphere, where aerosol emissions are not as pervasive.

Gettelman said the study will help scientists better understand the influence of various types of aerosols in different atmospheric conditions, helping to inform efforts to minimize climate change. Although the research illustrates how aerosols counter the warming influence of greenhouse gases, he emphasized that emitting more of them into the lower atmosphere is not a viable strategy for slowing climate change.

“Aerosol emissions have major health ramifications,” he said. “Saying we should pollute is not practical.”

Reference: “Climate Impacts of COVID‐19 Induced Emission Changes” by A. Gettelman, R. Lamboll, C. G. Bardeen, P. M. Forster and D. Watson‐Parris, 29 December 2020, Geophysical Research Letters.
DOI: 10.1029/2020GL091805

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SpaceX launches two Starlink missions in 24 hours – Teslarati

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Two SpaceX Falcon 9 rockets have completed back-to-back Starlink launches less than 24 hours apart, successfully delivering 106 Starlink satellites to low Earth orbit (LEO).

Originally scheduled just a handful of hours apart, slight delays eventually saw Starlink 4-13 and Starlink 4-15 settle on 6:07 pm EDT, May 13th and 4:40 pm EDT, May 14th, respectively. Entering the final stretch, launch preparations went smoothly and both Falcon 9 rockets ultimately lifted off without a hitch.

Starlink 4-15, May 14th. (Richard Angle)

The series began with Starlink 4-13 on Friday. SpaceX chose Falcon 9 B1063 to support the Starlink launch and the booster did its job well, wrapping up its fifth launch since November 2020 with a rare landing aboard drone ship Of Course I Still Love You (OCISLY). Since SpaceX permanently transferred OCISLY from the East Coast to the West Coast in mid-2021, the drone ship has only supported five booster recoveries. Save for an unusual East Coast Starlink launch in May 2021, Falcon 9 B1061 has also primarily been tasked with supporting SpaceX’s West Coast launch manifest. With only one older pad – Vandenberg Space Force Base’s (VSFB) SLC-4 complex – available to SpaceX, the company’s West Coast Falcon launches are also considerably rarer than its East Coast missions.

SpaceX has also taken to using the pad – which is in an optimal location to launch satellites that orbit Earth’s poles – to launch several batches of Starlink satellites into more ordinary equatorial orbits, essentially augmenting the capabilities of its two Florida launch sites.

Starlink 4-13 and 4-15 were more or less identical, in that regard; both launched 53 Starlink V1.5 satellites into LEO to continue filling out the fourth of five Starlink orbital ‘shells’ that will make up SpaceX’s first licensed constellation. Since SpaceX began Plane 4 (or Group 4) launches in November 2021, the company has now completed 15 missions that carried a total of 860 Starlink V1.5 satellites into orbit. Excluding a solar storm-related fluke that destroyed almost an entire launch worth of satellites, all but 8 remain operational in orbit. According to astronomer Jonathan McDowell’s independent tracking, about 300 Group 4 Starlink satellites have reached operational orbits, while another 500 or so are either raising their orbits or waiting for the right moment to do so.

The original and current planned orbits of SpaceX’s first Starlink constellation. (WCCF Tech)

As of May 2022, the first shell or ‘group’ of SpaceX’s first Starlink constellation has about 1500 operational Starlink satellites of a nominal 1584. If all working Group 4 satellites currently in orbit become operational, SpaceX has another ~770 satellites or 15 launches to go to complete the shell (17 to finish Shell 1 and Shell 4). If SpaceX maintains its current six-month launch cadence of one Starlink mission every ~11 days, SpaceX’s first Starlink constellation could have around 3400 working satellites in orbit and be more than three-quarters complete by the end of 2022.

SpaceX, by all appearances, fully intends to push its vehicles and workforce to the absolute limits in 2022 in a bid to complete as many as 60 orbital launches. To launch Starlink 4-15, for example, SpaceX made an unprecedented decision to debut a brand new Falcon 9 booster on the internal mission, demonstrating just how fully its customers have embraced reusability and how much the company wants to expand its fleet of Falcon 9 boosters as quickly as possible.

Following Starlink 4-13 and 4-15, SpaceX has completed 20 launches in the first 19 weeks of 2022 and has another two launches scheduled in the last two weeks of May.

SpaceX launches two Starlink missions in 24 hours





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Photos: Total lunar eclipse bathes Moon in red – Al Jazeera English

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Skywatchers have gathered in different parts of the globe to enjoy a total lunar eclipse that graced the skies for longer than usual.

For about an hour and a half on Sunday night into early Monday morning, the Moon was bathed in the reflected red and orange hues of the Earth’s sunsets and sunrises.

It was one of the longest totalities of the decade and the first so-called “Blood Moon” in a year.

Observers in the eastern half of North America and all of Central and South America had prime seats for the whole show, weather permitting.

Partial stages of the eclipse were visible across Africa, Europe and the Middle East.

A total eclipse occurs when the Earth passes directly between the moon and the sun and casts a shadow on our constant, cosmic companion.

The moon was expected to be 362,000km (225,000 miles) away at the peak of the eclipse.

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Q and A: She discovered the black hole at the center of our galaxy. This week, she finally saw it – Phys.org

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Credit: EHT Collaboration, CC BY-SA

This week, the world got its first-ever look at Sagittarius A*, the supermassive black hole in the center of our galaxy. The image of a hazy golden ring of superheated gas and bending light was captured by the Event Horizon Telescope, a network of eight radio observatories scattered across the globe.

Feryal Özel, a University of Arizona astronomer and founding member of the EHT consortium, said that seeing the black hole’s image was like finally meeting in real life a person you’ve only interacted with online.

For Andrea Ghez, an astrophysicist at UCLA, the encounter was perhaps more like a biographer meeting her subject after decades of pursuit.

In 2020, Ghez was awarded the Nobel Prize in physics for her role in the discovery of a supermassive object at the core of the Milky Way. That object is now known to be Sagittarius A*, or Sgr A* for short.

Ghez studies the center of our galaxy and the orbits of thousands of stars encircling the dense object at its very heart. Though she wasn’t involved with the EHT project, she said its “impressive” achievements—including its 2019 unveiling of the black hole anchoring a distant galaxy known as Messier 87—offer intriguing new possibilities for the study of the cosmos.

The Los Angeles Times spoke to her about black holes, cosmic surprises and what Einstein has to do with the GPS app on your phone. The interview has been edited for length and clarity.

How does it feel to finally lay eyes on the thing you’ve spent your career studying?

It’s super exciting. We live in a really interesting moment where technology is advancing so rapidly in so many arenas and giving us new insights into these incredibly exotic objects.

Does it look different than you anticipated?

No, actually. It’s remarkably similar. You should see this ring at roughly two and a half times the Schwarzschild radius (the radius of the event horizon, the boundary around a black hole beyond which no light or matter can escape). That’s the prediction of where gravity should bend, and that’s exactly where you see it. That’s impressive.

How much have technological capabilities changed for researchers since you started studying black holes?

Huge, huge advances. I often say we’re surfing on a wave of technological development. Everything that we do really can be described as technology-enabled discovery.

One of the things that I love about working in these areas where the technology is evolving really quickly is that it affords you the opportunity to see the universe in a way you haven’t been able to see before. And so often that reveals unexpected discoveries.

We’re really lucky that we’re living at this moment where technology is evolving so quickly that you can really rewrite the textbooks. The Event Horizon Telescope is a similar story.

What unanswered questions about the universe excite you most?

I have a couple favorites right now. The one that I’m super excited about is our ability to test how gravity works near the using star orbits, and also as a probe of dark matter at the center of the galaxy. Both of those things should imprint on the orbits.

A simple way that I like to think about it is: The first time around, these orbits tell you the shape. And then after that you get to probe more detailed questions because you kind of know where in space the star is.

For example, S0-2 (which is my favorite star in the galaxy, and probably in the universe) goes around every 16 years. Now we are on the second passage, and that’s giving us the opportunity to test Einstein’s theories in ways that are different than what the Event Horizon Telescope is probing, as well to constrain the amount of dark matter that you might expect at the center of the galaxy. There are things that we don’t understand about the early results, and to me that’s always the most exciting part of a measurement—when things don’t make sense.

What’s your approach in those moments?

You have to have complete integrity with your process. Things may not make sense because you’re making a mistake, which is the uninteresting result, or they may not make sense because there’s something new to be discovered. That moment when you’re not sure is super interesting and exciting.

We’ve just discovered these objects at the center of the galaxy that seem to stretch out as they get close to the black hole, then become more compact. They’re called tidal interactions. If you think of the movie “Interstellar” with that big giant tidal wave, this would be like a big tidal wave that just lifts off the planet. If we’re seeing stars having those kinds of interactions, it means that the star has to be, I don’t know, a hundred times larger than anything we predicted to exist in this region. So that makes you scratch your head.

Does the new image of Sgr A* reinforce your finding that, for now, Einstein’s theory of general relativity seems to do the best job of explaining how gravity operates throughout the universe?

Yes. Absolutely. Black holes kind of represent the breakdown of our understanding of how gravity works. We don’t know how to make gravity and quantum mechanics work together. And you need those two things to work together to explain what a black hole is, because a black hole is strong gravity plus an infinitesimally small object.

Wait, what? I thought black holes were huge

No. The image is of the phenomena that happens around the black hole. The black hole has no finite size, but there is this abstract size of the event horizon, which is the last point that light can escape. And then the gravitational interaction with local light gets concentrated in this ring that’s two-and-a-half times bigger that the event horizon.

Anyway, we know that represent the breakdown of our knowledge. That’s why everyone keeps testing Einstein’s ideas about gravity there, because at some point you expect to see what you might call the expanded version of gravity, in the same way that Einstein was the expanded version of Newton’s version.

Is it fair to say that Newton’s laws do a decent job of explaining how gravity works here on our little planet, but we need Einstein once we head out into the universe?

Yes, except for what we take for granted today: our cellphones. The fact that we can find ourselves so well on Google or Waze or your favorite traffic app is because GPS systems position your phone with respect to satellites going around the Earth. Those systems have to use Einstein’s version of gravity. So, yes. We could use Newton until we cared about things like this.


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Seeing Milky Way’s new black hole is ‘only the beginning’: US researcher


©2022 Los Angeles Times.
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Q and A: She discovered the black hole at the center of our galaxy. This week, she finally saw it (2022, May 16)
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