Month: July 2024

When you think of background radiation, most people immediately think of the cosmic optical background and stories of pigeon droppings during their discovery. But that's another story. It turns out that the universe has multiple background radiations, such as infrared and even gravitational wave backgrounds. NASA's New Horizons is now far enough from the solar system to be in the perfect place to measure the cosmic optical background (COB). Most of this light comes from the stars in galaxies, but astronomers have always wondered if there are other sources of light filling our night sky. New Horizons has an answer. No!

OK, let's talk about pigeon droppings. In 1965, two telecommunications engineers at Bell Laboratory were studying signal interference. Penzias and Wilson detected a faint “hum” in all directions and initially attributed it to pigeon droppings lodged in the horn of the radio receiver. But in fact they had discovered the cosmic background radiation, the faint glow that permeates the entire universe and is the thermal radiation left over from the Big Bang. By studying them, we can learn more about the universe when it was 380,000 years old.

The full sky picture of temperature variations (shown as color differences) in the cosmic microwave background radiation, created from nine years of WMAP observations. These are the seeds of galaxies from a time when the universe was less than 400,000 years old. Image credit: NASA/WMAP

In the late 1980s, another type of background radiation was discovered: the infrared background radiation. It consists of the diffuse infrared glow that fills the universe and comes from numerous sources throughout the history of the universe. It consists mainly of thermal emissions from dust grains heated by stellar radiation. In addition, there is the gravitational wave background radiation, but this has not yet been discovered.

Another hotly debated background is the cosmic optical background (COB), a diffuse light emitted by stars and galaxies that spans the entire visible spectrum. Its study has gained momentum, however, thanks to observations from the Hubble Space Telescope and the Spitzer Infrared Telescope. However, studies have shown that a large contribution to an overall optical background glow comes from faint, unresolved galaxies. Studying the COB allows us to explore the overall energy output of the universe, as well as the formation of galaxies and stars throughout the history of the cosmos.

However, detecting the COB is challenging because Earth-based instruments or even those in Earth's orbit are plagued by interference. Zodiacal light, for example, is caused by the scattering of sunlight by interplanetary dust. It is prevalent in the inner solar system and makes studying the COB difficult. The New Horizons probe is ideally positioned beyond Pluto's orbit, over 8 billion kilometers from interference. On board New Horizons is the Long Range Reconnaissance Imager (LORRI) camera, which has been identified as the ideal platform to begin a search.

The payload of the New Horizons instrument, which is currently conducting planetary science, heliospheric measurements, and astrophysical observations. Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Using images from the LORRI camera, a team of astronomers led by Marc Postman of the Space Telescope Science Institute attempted to measure the COB in the range of 0.4 to 0.9 micrometers. The images were taken from high galactic latitudes to ensure there was no diffuse light from the Milky Way or scattered light from bright stars. Isolating the COB's contribution to the sky's overall brightness required digitally subtracting the scattered light from bright stars and galaxies, as well as from faint stars within the field that were dimmer than that detected by LORRI. Interestingly, the results showed that, based on the estimated number of galaxies in the regions studied, the COB is the result of light from all galaxies within our observable region of the universe.

Source: New synoptic observations of the cosmic optical background with New Horizons

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Craters are a familiar sight on the surface of the Moon and many rocky planets in the solar system. Other circular structures can be seen in orbiter images, but these pits are likely the collapsed roofs of lava tubes. A team of researchers has mapped one of these tubes using radar reflections and created the first 3D map of the tube's entrance. Places like these could be ideal locations for establishing research stations, protected from the harsh environment of an alien world.

Lava tubes have been hotly debated for 50 years. They are the result of ancient volcanic activity and are formed when the surface of a lava flow cools and hardens. Beneath, the molten lava continues to move and eventually drains away, leaving behind a hollow tunnel. Studying these tunnels can tell us more about the Moon's geological history through the record preserved in the rocks.

The lava tubes were studied by NASA's Lunar Reconnaissance Orbiter (LRO), which began its journey in 2009. Its goal was to collect information about the Moon's surface and environment, and to that end it had a wealth of scientific equipment. LRO has mapped the lunar surface with high-resolution images that capture temperature, radiation levels, and water ice deposits. All with the goal of identifying possible landing sites for future missions.

Artist's impression of the Lunar Reconnaissance Orbiter (LRO) in orbit. Image credit: ASU/LROC

A team of scientists from all over the world have worked together to make a breakthrough in the study of these tubes. The research was led by the University of Trento in Italy and the results published in Nature Astronomy. They have discovered the first confirmed tunnel just beneath the lunar surface, which appears to be an empty lava tube. Until now, their existence was just a theory, now they are a reality.

The discovery would not have been possible without the LRO and its miniature radio frequency instrument. In 2010, it surveyed Mare Tranquilitatis – the site of Apollo 11's historic moon landing in 1969 – and collected data including the region around a pit. This new research re-analyzed the data using modern complex signal processing techniques. The analysis revealed previously unidentified radar reflections that are best explained by an underground cave or tunnel. Perhaps intriguingly, this is an underground tunnel on the lunar surface, but it is also accessible.

Buzz Aldrin looks out over Tranquility Base during Apollo 11's moonwalk. Photograph by Neil Armstrong. Image credit: NASA

The discovery underscores the importance of continued analysis of historical data, including data from decades ago, to find hidden information that modern techniques can reveal. It also underscores the importance of further remote sensing and orbital lunar exploration to identify more lava tubes as potential safe havens for lunar explorers.

Travelers on the Moon can experience temperatures ranging from 59 degrees on the lit side to -79 degrees on the night side. Radiation from the Sun can reach – pardon the pun – up to 150 times the intensity here on Earth, and that's not even taking into account the threat of meteor strikes. Thanks to the atmosphere, we're protected from thousands of tons of that stuff, but there's no shield on the Moon. If we build structures on the Moon's surface, they'll have to be built to withstand such a hostile environment, but when you look at lava tubes, many of the problems naturally disappear, making it a far safer and more cost-effective way to establish a presence on the Moon.

Source: Existence of a lava tube cave on the moon proven

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Originally published at ClimateREALISM

Image: Green areas showed growth in leaves from 2000 to 2017, while brown areas showed a decline. JOSHUA STEVENS / NASA EARTH OBSERVATORY

An article published on July 16 by Yale Environment 360 claims that global greening is not a positive thing, but rather a negative thing, because it will damage water supplies. This claim is amusing at best and misleading at worst. Although the author admits that many scientists see greening the Earth as beneficial due to rising CO2 levels, especially desert regions, he tries to portray this as a negative thing.

The article “As CO2 levels rise, the world's drylands are turning green” in the magazine Yale Environment 360 is amusing because its author, Fred Pearce, could not resist turning some very positive news into a negative one.

The subtitle of the article is:

Despite warnings that climate change could lead to large-scale desertification, many drylands are becoming greener as CO2 levels in the air rise – a trend that recent studies suggest will continue. But scientists warn that the increased vegetation could drain scarce water supplies.

First of all, we should commend Yale Environment 360 for spreading the good news about the effect of carbon dioxide (CO2) on greening the planet. The article adds:

What's going on here? The main reason, according to recent studies, is the 50 percent increase in carbon dioxide concentration in the atmosphere since pre-industrial times. This increased CO2 level is not only driving climate change, but also speeding up plant photosynthesis. By allowing plants to use scarce water more efficiently, the CO2-rich air fertilizes plant growth in even some of the driest places.

We have already reported on this greening due to increased CO2 levels here on Climate Realism. Data from satellite measurements show that the green area of ​​the Earth increased by about 5% in the first 20 years of the 21st century. This is making the Sahara smaller. A 2018 study by Venter et al. found that the area of ​​the Sahara has shrunk by 8% in the last three decades.

However, Pearce's claim is controversial: “Scientists warn, however, that the additional vegetation could drain scarce water supplies.”

That is simply wrong. In Africa, for example, trees make desert land fertile again:

There is finally some good news from Africa. Farmers are reclaiming the desert and transforming the barren wastelands of the Sahel zone on the southern edge of the Sahara into green, productive farmland.

Satellite images taken this year and 20 years ago show that the desert is receding thanks to reforestation, mainly with ana trees (Faidherbia albida), a type of acacia. Wherever the trees grow, agriculture can be resumed.

By planting trees, around three million hectares of land in Niger have been reforested, meaning that around 250,000 hectares can be used for agriculture again.

The key factor is evapotranspiration. Evapotranspiration, which is the combination of evaporation and plant transpiration (water from leaves into the air), is a key factor in desert formation. Deserts form when the amount of water evaporating from the ground is greater than the amount of rain or snow that falls. This is because deserts are arid, or dry, and receive no more than 10 inches of rainfall per year.

Evapotranspiration is an energy-driven process that increases with temperature, solar radiation, and wind. In deserts, the rapid heating and cooling of air creates strong winds that circulate hot, dry air, further increasing the rate of evaporation. In American deserts, for example, evaporation can range from 70 to 160 inches per year. At this rate of water loss, deserts remain deserts—they are locked in by the process of evaporation.

But in trees, this cycle is broken. Tree leaves reflect and absorb sunlight, reducing the amount of sunlight reaching the ground and lowering soil temperatures. At lower soil temperatures, the sun protection provided by tree canopies actually reduces evaporation, helping the desert to retain more groundwater.

Moderate warming has already led to slightly higher rainfall. In addition, plants use water more efficiently under higher CO2 conditions because they lose less moisture through transpiration, as Agronomy and Botany explains. So plants use water more efficiently and the increase in plants reduces moisture loss in dry regions. How terrible!

This has been known basic plant science for decades, reducing any claimed increase in water use, but Pearce has completely missed it. Or maybe he knows about it and prefers to keep the “CO2-related climate change is the cause of everything bad that's happening on Earth” narrative alive, no matter what the facts are.

Given the many examples we present here at Climate Realism each week of the media sticking to their narrative despite facts to the contrary, it is not surprising that Yale Environment 360 has attempted to turn good news about global greening into bad news. Shameful, but not surprising. For climate alarmists, maintaining the narrative seems more important than reporting the facts.

Anthony Watts

Anthony Watts is a senior fellow for environment and climate at the Heartland Institute. Watts has been in the weather business on and off camera since 1978 as a television meteorologist and currently produces daily radio forecasts. He has developed weather graphics presentation systems for television and specialty weather instruments and has co-authored peer-reviewed articles on climate issues. He runs the world's most visited climate website, the award-winning wattsupwiththat.com.

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