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“The best laid plans of mice and men often go awry” – this famous paraphrase of Scottish poet Robert Burns sometimes sums up human ingenuity.  That is exactly what happened when a county in Washington State decided to replace all of its county-owned streetlights with LEDs at least partially in an effort to combat light pollution.  New research shows that they actually made the light pollution worse.

Dr. Li-Wei Hung and her colleagues at the National Park Service recently released a paper currently available on arXiv that details work that they did to monitor the night sky both before and after Chelan County replaced their streetlights with LEDs.

Map of Chelan County and where its street lights are located.
Map of Chelan County and where its street lights are located.
Credit – Hung et al.

Chelan County is located in the north-central part of the state and serves as a gateway to several outdoor recreational areas nearby, including North Cascades National Park.  Given this interest in the outdoors, less light pollution would seem like a benefit to stargazing hoping to catch a glimpse of the Milky Way.

So the county decided to replace all 3,693 of the county-owned streetlights (60% of the total outdoor streetlights in Chelan County) with “full cutoff” light emitting diodes for bulbs.  About 80% of these new LEDs were “3000K” or “warm white light”, while the other 20% were slightly brighter “4000K” bulbs that were installed to meet lighting requirements set by the Washington State Department of Transportation.

NG video on Light Pollution.
Credit – National Geographic YouTube Channel

The retrofit process took place between 2018 and 2019, and Dr. Hung and her team took measurements both before the install and after all of the new lights were in place.  What they found was…surprising to say the least.  The sky actually got brighter in the county after the LEDs were installed.

Such a result is only counterintuitive because LEDs are generally thought of as being much more energy efficient and better for light pollution.  An experiment in Flagstaff, Arizona attempted to leverage LEDs to create the world’s first “International Dark Sky City” in 2018, though results are still out on its effectiveness.  

Video discussing the some of the best places to stargaze in the US.
Credit – Check Facts 360 YouTube Channel

If the results in Chelan County are anything to go by that experiment might not be successful.  Dr. Hung and her colleagues looked at three different metrics of calculating how dark the sky is – how bright the skyglow in the county was, how high it went, and “upward radiance” which measures the light directed upward.

Several tools were needed to comprehensively calculate the differences in light pollution.  First, the National Park Service has a “night sky camera system”, which allowed the researchers to take simple before and after pictures of the night sky in the Chelan County area.  More data was then collected by the Visible Infrared Imaging Radiometer Suite (VIIRS), which is located on the Suomi National Polar-orbiting Partnership Satellite.

Description of Suomi and it’s associated data.
Credit – USGS

Of the three metrics measured by these instrument, the brightness and height of the skyglow increased, while the upward radiance actually decreased.  The explanation the authors put forward for why exactly the light pollution got worse is that there was an increase in light emissions shorter than 500 nm, closer to the blue end of the visible spectrum.  As for why the amount of light directed upward decreased, it was most likely due to a combination of the directionality of the LEDs as well as better shielding on the lamppost themselves.

Despite actually making light pollution slightly worse, the LED retrofit can still be considered a success for its other two goals – decreasing energy consumption and cost.  The LEDs are undeniably more energy efficient than the high pressure sodium lamps they replaced, and will last much longer, decreasing their overall cost to the county.  While the energy and cost savings are great, astronomy enthusiasts everywhere can hope that other municipal authorities that are considering similar upgrades can take into account how new LEDs might affect their night skies.  Utilizing all of the best aspects of LEDs could lead to happy humans and mice all around.

Learn More –
arXiv – Changes in night sky brightness after a countywide LED retrofit
Chelan County – Sharing the Night Sky
UT – Most light pollution isn’t coming
Did you miss our previous article…
https://www.mansbrand.com/there-are-probably-many-more-earth-sized-worlds-than-previously-believed/

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Should We Send Humans to Venus?

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NASA is preparing to send humans back to the Moon with the Artemis missions in the next few years as part of the agency’s Moon to Mars Architecture with the long-term goal of landing humans on the Red Planet sometime in the 2030s or 2040s. But what about sending humans to other worlds of the Solar System? And, why not Venus? It’s closer to Earth than Mars by several tens of millions of kilometers, and despite its extremely harsh surface conditions, previous studies have suggested that life could exist in its clouds. In contrast, we have yet to find any signs of life anywhere on the Red Planet or in its thin atmosphere. So, should we send humans to Venus?

“Yes, we should send humans to Venus,” Dr. Paul Byrne, who is an Associate Professor of Earth, Environmental, and Planetary Sciences at Washington University in St. Louis, tells Universe Today. “But first, let’s talk about what ‘sending humans to Venus’ actually means. The surface of Venus is hellish, so nobody would last long there nor volunteer to go. Above the clouds, the temperature and pressure are almost like a nice spring day here on Earth, so aside from tiny sulphuric acid cloud droplets you’d be okay (with a breathing apparatus).”

These “hellish” conditions that Dr. Byrne alludes to are the extreme conditions across the surface of Venus, including surface pressures 92 times that of Earth’s surface and average surface temperatures of approximately 464 degrees Celsius (867 degrees Fahrenheit). In contrast, Earth’s average surface temperatures are a calm 15 degrees Celsius (59 degrees Fahrenheit). These extreme pressures and temperatures have made landing on the surface of Venus even more difficult, as the former Soviet Union continues to be the only nation to have successfully landed on Venus’ surface, having accomplished this feat with several of their Venera and Vega missions. However, the longest mission duration for the lander was only 127 minutes (Venera 13), which also conducted the first sound recording on another planet.

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Color images taken by the Soviet Union’s Venera 13 lander on the surface of Venus on March 1, 1982, with the lander surviving only 127 minutes due to Venus’s extreme surface conditions. (Credit: NASA)

“If we were to send humans to Venus, they’d be going in a spacecraft that would fly by the planet en route somewhere else,” Dr. Byrne tells Universe Today. “If we were to one day send humans actually to Venus itself for science and engineering purposes, then a cloud-based habitat is the way to go. Getting humans onto the Venus surface is going to require so much technology and expense that, for the foreseeable future, I don’t think anyone will think it worth doing.”

A 2015 study presented at the AIAA Space and Astronautics Forum and Exposition outlined a NASA study for the High Altitude Venus Operational Concept (HAVOC) mission that would involve a 30-day crewed mission using an airship equipped with solar panels within the upper atmosphere of Venus. This is because Venus’ upper atmosphere at approximately 50 kilometers (30 miles) above the surface exhibits much more hospitable conditions, including temperatures between 30 to 70 degrees Celsius (86 to 158 degrees Fahrenheit) and pressures very close to that of Earth. However, Dr. Byrne refers to HAVOC as an “unbelievably expensive concept”.

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Artist rendition of proposed habitable airships traversing Venus’ atmosphere, which has been proposed as the High Altitude Venus Operational Concept (HAVOC) mission. (Credit: NASA)

As for using Venus while en route to another location in the Solar System, Venus has been used on several occasions to slingshot spacecraft to the outer Solar System as well as for exploration of the inner Solar System, such as Mercury and the Sun. For example, NASA’s Galileo and Cassini spacecraft used gravity assists

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We Should Hit Peak Solar Activity Next Year

NASAs SDO Observes Largest Sunspot of the Solar Cycle 15430820129 jpeg

You may be familiar with the solar cycle that follows a 22 year process shifting from solar minimum to maximum and back again. It’s a cycle that has been observed for centuries yet predicting its peak has been somewhat challenging. The Sun’s current cycle is approaching maximum activity which brings with it higher numbers of sunspots on its surface, more flares and more coronal mass ejections. A team from India now believe they have discovered a new element of the Sun’s magnetic field allowing them to predict the peak will occur early in 2024.

The Sun is a gigantic sphere of plasma or electrically charged gas. One of the features of plasma is that if a magnetic field passes through it, the plasma moves with it. Conversely if the plasma moves, the magnetic field moves too. This magnetic field is just like Earth and is known as a dipole magnetic field. You can visualise it if you can remember your school science days with a bar magnet and iron filings.

A dipole magnetic field has two opposite but equal charges and at the start of the Sun’s cycle the field lines effectively run from the north pole to the south. As the Sun rotates, with the equator rotating faster than the polar regions, then the plasma drags the magnetic field lines with it, winding them tighter and tighter.

The field lines become stretched causing the magnetic field to loop up and through the visible surface of the Sun. This localised event prevents the convection of super heated gas from underneath and appears as a cooler area of the surface which appears dark. As the solar cycle starts, these sunspots appear around the polar regions and slowly migrate toward the equator as it progresses with peak activity occurring when the sunspots fade away as we head toward the start of another cycle. 

NASAs SDO Observes Largest Sunspot of the Solar Cycle 15430820129 1 jpeg
Image of sunspots (Credit : NASA Goddard Space Flight Center // SDO)

On occasions the magnetic field of sunspots are disrupted and we can experience flares or coronal mass ejections hurling vast amounts of charged particles out into space. If they reach us here on Earth they give rise to the beautiful aurora displays but they do also have a rather negative impact to satellites, power grids and telecommunications systems.

Deep inside the Sun, a dynamo mechanism is driving all this. It is created by the energy from the movement of plasma and it is this that is responsible for the flipping of the Sun’s magnetic poles where the north pole becomes south and the south pole becomes north which happens every 11 years or so. It’s another aspect of the solar cycle.

It’s been known since the 1930’s that the rate of rise the sunspot cycle relates to its strength with stronger cycles taking less time to reach peak. In the paper published in the Monthly Notices of the Royal Astronomical Society Letters; Priyansh Jaswal, Chitradeep Saha and Dibyendu Nandy from the Indian Institutes of Science Education and Research announced their findings. They discovered that the rate of decrease in the Sun’s dipole magnetic field also seems to relate to the rise of the present cycle.

The team have looked back through archives and have shown how the observation of the dipole decrease rate along with observations of sunspots can predict the peak of activity with better accuracy than before. They conclude the current cycle is expected to peak somewhere between early 2024 and September next year. Being able to better predict the peak of activity will help understand the likely intensity of space weather events here on Earth providing us more warning to be able to prepare.

Source : Solar activity likely to peak next year, new study suggests

The post We Should Hit Peak Solar Activity Next Year appeared first on Universe Today.

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The Solar Radius Might Be Slightly Smaller Than We Thought

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Two astronomers use a pioneering method to suggest that the size of our Sun and the solar radius may be due revision.

Our host star is full of surprises. Studying our Sun is the most essential facet of modern astronomy: not only does Sol provide us with the only example of a star we can study up close, but the energy it provides fuels life on Earth, and the space weather it produces impacts our modern technological civilization.

Now, a new study, titled The Acoustic Size of the Sun suggests that a key parameter in modern astronomy and heliophysics—the diameter of the Sun—may need a slight tweak.

The study out of the University of Tokyo and the Institute of Astronomy at Cambridge was done looking at data from the joint NASA/ESA Solar Heliospheric Observatory (SOHO’s) Michelson Doppler Imager (MDI) imager. The method probes the solar interior via acoustics and a cutting edge field of solar physics known as helioseismology.

Interior of the Sun
A cutaway diagram of the Sun. NASA/ESA/SOHO

‘Hearing’ the Solar Interior

How can you ‘hear’ acoustic waves on the Sun? In 1962, astronomers discovered that patches on the surface of the Sun oscillate, or bubble up and down, like water boiling on a stove top. These create waves that ripple in periodic 5-minute oscillations across the roiling surface of the Sun.

SOHO SDO
A view of the Sun, courtesy of SOHO’s MDI instrument. Credit: NASA

What’s more, astronomers can use what we see happening on the surface of the Sun to model the solar interior, much like terrestrial astronomers use seismic waves traveling through the Earth to model its core. Thanks to helioseismology, we can even ‘see’ what’s going on on the solar farside, and alert observers of massive sunspots before they rotate into view.

Solar Ffarside
Solar farside modeling using helioseismology. Credit: NSF/GONG

The study looked at p-mode waves as they traversed the solar interior. Previous studies relied on less accurate f-mode waves, which are surface waves considerably shorter than the solar radius.

The study defines the solar radius (half the diameter) as 695,780 kilometers… only slightly smaller than the generally accepted radius of 696,000 kilometers obtained by direct optical measurement. This is only smaller by a few hundredths of a percent, or 100-200 kilometers.

SOHO
An artist’s conception of SOHO in space. Credit: ESA/SOHO

The solar radius is a deceptively simple but crucial factor in astronomy. The Sun is a glowing ball of hydrogen and helium plasma without a distinct surface boundary. The photosphere—the glowing visible layer we see shining down on us on a sunny day—is what we generally refer to as the surface of the Sun.

The Solar Radius: A Brief
Did you miss our previous article…
https://mansbrand.com/if-warp-drives-are-impossible-maybe-faster-than-light-communication-is-still-on-the-table/

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