Science
To Protect Wildlife from Artificial Light, Look to the Moon
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Camilla Rathsach walked along the lichen-covered sand, heading out from the lone village on Denmark’s remote Anholt island—a spot of land just a few kilometers wide in the middle of the Kattegat Strait, which separates the Danish mainland from Sweden. As Anholt Town’s 45 streetlights receded into the distance, moonlit shadows reached out to embrace the dunes. Rathsach looked up, admiring the Milky Way stretching across the sky. Thousands of stars shone down. “It’s just amazing,” she says. “Your senses heighten and you hear the water and feel the fresh air.”
This dark-sky moment was one of many Rathsach experienced while visiting the island in 2020 for work on her master’s thesis on balancing the need for outdoor lighting and darkness. Having grown up in urban areas, Rathsach wasn’t used to how bright moonlit nights could be. And after speaking with the island’s residents, who value the dark sky deeply and navigate with little outdoor light, she realized that artificial lighting could be turned down at night depending on the moon’s phase.
At Aalborg University in Denmark, she worked with her graduate supervisor, Mette Hvass, to present a new outdoor lighting design for Anholt’s church. Rathsach and Hvass picked the church for their project because it is a central meeting place for the community yet it currently has no outdoor lights. They thought lighting would make it easier for people to navigate but wanted to preserve the inviting ambiance of moonlight.
One of the guiding principles of designing sustainable lighting is to start with darkness, and add only the minimum amount of light required. Darkness and natural light sources are important to many species, and artificial light can be downright dangerous.
“Lights can attract and disorient seabirds during their flights between colony and foraging sites at sea,” says Elena Maggi, an ecologist at the University of Pisa in Italy who is not involved in the project. Anholt’s beaches host a variety of breeding seabirds, including gulls and terns, and the island is a stopover for many migrating birds. The waters around the island are also home to seals, cod, herring, and seagrass. Though scientists have made progress in understanding the effects of artificial light at night on a range of species, such as turtles, birds, and even corals, there is still more to learn.
“We still don’t know exactly how artificial light might interact with other disturbances like noise and chemical pollution, or with rising ocean temperatures and acidification due to climate change,” says Maggi.
The scientists’ final design for the church includes path lighting and small spotlights under the window arches, along with facade lighting under the eaves shining downward. To preserve the dark sky, path lighting would turn off on bright moonlit nights, and facade lighting would shut off on semi-bright or bright nights. The window lighting would stay on regardless of the moon’s phase.
The adaptive lighting cooked up by Camilla Rathsach and Mette Hvass would automatically adjust to the availability of moonlight, tweaking this church’s lighting automatically to balance visibility and darkness. Mock-ups show how the church would be lit under no moonlight (first) and a full moon (second). Illustrations courtesy of Camilla Rathsach
“The contrast between the moon’s cold white light reflecting off the church’s walls and the warm orange lights in the windows would create a cozy, inviting experience,” says Rathsach.
The moonlight adaptive lighting design project is part of a growing effort to balance the need for functional lighting in the town and to protect the darkness. Recently, the town’s public streetlights were swapped for dark-sky friendly lamps, says Anne Dixgaard, chairman of Dark Sky Anholt.
Dixgaard also organizes a yearly walk out to Anholt’s beach, where skywatchers can learn about the night sky. “People really value Anholt’s dark sky and want to preserve it,” she says.
Rathsach and Hvass are working on the moonlight adaptive design project in hopes that it will be implemented one day, but they still have some challenges to overcome. Moonlight is a relatively faint light source, so detecting it using sensors is challenging, and lights would need to adjust automatically on nights with intermittent cloud cover. Yet big initiatives often begin with small steps.
“This work is something new and unexpected,” says Maggi. “It’s a very interesting approach to mitigating the negative effects of artificial light at night.”
This visualization shows water features on New York’s Long Island – shown as bright pink splotches. Purple, yellow, green, and dark blue shades represent different land elevations, while the surrounding ocean is a lighter blue. The data was collected on Jan. 21, 2023, by SWOT’s KaRIn instrument. Credit: NASA/JPL-Caltech
The Surface Water and Ocean Topography mission offers the first taste of the detailed perspectives of Earth’s surface water that its cutting-edge instruments will be able to capture.
The international Surface Water and Ocean Topography (SWOT) mission – led by NASA and the French space agency Centre National d’Études Spatiales (CNES) – has sent back some of its first glimpses of water on the planet’s surface, showing ocean currents like the Gulf Stream in unprecedented detail. SWOT is also capturing views of freshwater features such as lakes, rivers, and other water bodies down to about 300 feet (100 meters) wide.
The satellite will measure the elevation of nearly all the water on Earth’s surface and provide one of the most comprehensive surveys yet of our planet’s surface water. SWOT’s measurements of freshwater bodies and the ocean will provide insights into how the ocean influences climate change and the water cycle; how a warming world affects water storage in lakes, rivers, and reservoirs; and how communities can better manage their water resources and prepare for floods and other disasters.
“SWOT’s advanced imagery will empower researchers and advance the way we manage fresh water and the effects of sea level rise across the globe,” said NASA Administrator Bill Nelson. “Water is one of our planet’s most important resources – and it’s proven to be vulnerable to the impacts of climate change. SWOT will provide critical information that communities can use to prepare for the impacts of a warming climate.”
A Whole New View
As seen in these early images, on Jan. 21, 2023, SWOT measured sea level in a part of the Gulf Stream off the coast of North Carolina and Virginia. The two antennas of SWOT’s Ka-band Radar Interferometer (KaRIn) instrument acquired data that was mapped as a pair of wide, colored strips spanning a total of 75 miles (120 kilometers) across. Red and orange areas in the images represent sea levels that are higher than the global average, while the shades of blue represent sea levels that are lower than average.
For comparison, the new data is shown alongside sea surface height data taken by space-based instruments called altimeters. The instruments – widely used to measure sea level – also bounce radar signals off of Earth’s surface to collect their measurements. But traditional altimeters are able to look only at a narrow beam of Earth directly beneath them, unlike KaRIn’s two wide-swath strips that observe sea level as a two-dimensional map.
The spatial resolution of SWOT ocean measurements is 10 times greater than the composite of sea surface height data gathered over the same area by seven other satellites: Sentinel-6 Michael Freilich, Jason-3, Sentinel-3A and 3B, Cryosat-2, Altika, and Hai Yang 2B. The composite image was created using information from the Copernicus Marine Service of ESA (European Space Agency) and shows the same day as the SWOT data.
KaRIn also measured the elevation of water features on Long Island – shown as bright pink splotches nestled within the landscape. (Purple, yellow, green, and blue shades represent different land elevations.)
“Our ability to measure freshwater resources on a global scale through satellite data is of prime importance as we seek to adjust to a changing climate,” said CNES Chairman and CEO Philippe Baptiste. “In this respect, the first views from SWOT give us a clearer picture than ever before. These data will prove highly valuable for the international scientific community in the fields of hydrology, oceanography, and coastal studies.”
This initial inland image is a tantalizing indication of how SWOT can measure details of smaller lakes, ponds, and rivers in ways that satellites could not before. Such data will be used to produce an extraordinary accounting of the freshwater on Earth’s surface in ways useful to researchers, policymakers, and water resource managers.
“The KaRIn instrument took years to develop and build, and it will collect information on bodies of water across the globe – data that will be freely and openly available to everybody who needs it,” said Parag Vaze, SWOT project manager at NASA’s Jet Propulsion Laboratory in Southern California.
More About the Mission
Launched on Dec. 16, 2022, from Vandenberg Space Force Base in central California, SWOT is now in a period of commissioning, calibration, and validation. Engineers are checking out the performance of the satellite’s systems and science instruments before the planned start of science operations in summer 2023.
The data for these first images was collected by SWOT’s KaRIn instrument, the scientific heart of the satellite. KaRIn has one antenna at each end of a boom that’s 33 feet (10 meters) long. This enables the instrument to look off to either side of a center line directly below the satellite as it bounces microwave signals off Earth’s surface. The returning radar signals arrive at each antenna slightly out of sync, or phase, from one another. When these signals are combined with other information about the antennas and the satellite’s altitude, scientists will be able to map the height of water on Earth’s surface with never-before-seen clarity. KaRIn encountered an issue earlier this year with one of its subsystems; engineers have now resolved the situation, and the instrument is up and running.
SWOT was jointly developed by NASA and CNES, with contributions from the Canadian Space Agency (CSA) and the UK Space Agency. JPL, which is managed for NASA by Caltech in Pasadena, California, leads the U.S. component of the project. For the flight system payload, NASA provided the KaRIn instrument, a GPS science receiver, a laser retroreflector, a two-beam microwave radiometer, and NASA instrument operations. CNES provided the Doppler Orbitography and Radioposition Integrated by Satellite (DORIS) system, the dual frequency Poseidon altimeter (developed by Thales Alenia Space), the KaRIn radio-frequency subsystem (together with Thales Alenia Space and with support from the UK Space Agency), the satellite platform, and ground operations. CSA provided the KaRIn high-power transmitter assembly. NASA provided the launch vehicle and the agency’s Launch Services Program, based at Kennedy Space Center, managed the associated launch services.
To learn more about SWOT, visit: https://swot.jpl.nasa.gov/
The Earth witnessed a powerful solar storm in nearly six years, causing auroras all over the US, the National Oceanic and Atmospheric Administration (NOAA) said. NOAA had earlier announced moderate G2 storm and G3 conditions between March 23 and 25, but updated it to G4. A severe G4 storm can affect the power grid system with possible widespread voltage control problems; and spacecraft operations with increased possibility of surface charging, and atmospheric drag risk on Low Earth Orbiting (LEO) satellites.
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Five of the sun’s eight major planets will be lined up on the western horizon this Tuesday just after sunset.
The astronomical delight will comprise Mercury, Venus, Mars, Jupiter and Uranus — all in a visible line from the horizon to the crescent moon.
NASA astronomer Bill Cooke says the best way to get a glimpse is to stand somewhere with a clear view of the western horizon.
The planets will stretch from the horizon to halfway up the night sky.
Mercury and Jupiter (the first and fifth planets from the sun) will dip below the horizon around 30 minutes after sunset, that is 7:37 p.m. on Tuesday.
The five-planet spread can be seen anywhere on Earth.
Venus, Mars and Jupiter will be the brightest, particularly Venus, and Mars will be closest to the moon. Mercury and Uranus will be the dimmest, so a set of binoculars will be useful.
Uranus is the rarest seen of the planetary lineup.
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