Astronomy

Over the nearly 70 years of spaceflight, about 10 000 intact satellites and rocket bodies have reentered the atmosphere with many more to follow. Yet for such a ubiquitous event, we still lack a clear view on what actually happens to a satellite during its fiery last moments.

ESA is preparing the Destructive Reentry Assessment Container Object (Draco) mission that will collect unique measurements during an actual reentry and breakup of a satellite from the inside. A capsule especially designed to survive the destruction will transmit the valuable telemetry shortly after.

High-temperature superconducting cables that could transform the power grid may be increasingly viable, thanks to a side effect of fusion energy research and new ways to cool the wires

High-temperature superconducting cables that could transform the power grid may be increasingly viable, thanks to a side effect of fusion energy research and new ways to cool the wires

NASA astronaut Suni Williams did not expect to be taking command of the International Space Station when her eight-day Starliner Crew Flight Test launched in June. Now, the key to the station is hers.

The incompleteness of the fossil record complicates efforts to figure out how life on Earth is faring today

The universe’s hidden mass may be made of black holes, which could wobble the planets of the solar system when they pass by

Quirky perspectives, separated lovebirds and a tobogganing penguin star in 2024 winners of the world’s largest bird photography competition

Astronomers have discovered a "missing link:" a tiny black hole lurking with a red giant star in a strange and difficult-to-explain binary system.

Noctilucent clouds were once thought to be a fairly modern phenomenon. A team of researcher have recently calculated that Earth and the entire Solar System may well have passed through two dense interstellar clouds causing global noctilucent clouds that may have driven an ice age. The event is thought to have happened 7 million years ago and would have compressed the heliosphere, exposing Earth to the interstellar medium. 

Interstellar clouds are vast regions of gas and dust that flat between the stars inside galaxies. They are mostly made up of hydrogen along with a little helium and trace elements of heavier elements. They are a key part of the life circle of stars providing the materials for new stars to be formed and are seeded with elements after stars die. The clouds vary significantly in size, density and location and are an important part of the evolution of the Galaxy.

An annotated illustration of the interstellar medium. The solar gravity lens marks the point where a conceptual spacecraft in interstellar space could use our sun as a gigantic lens, allowing zoomed-in close-ups of planets orbiting other stars. Credits: Charles Carter/Keck Institute for Space Studies

Earth’s journey around the Galaxy is not for the impatient for it takes about 250 million years to complete one full orbit at a speed of 828,000 kilometres per hour. Currently the Solar System is located in the Orion Arm, one of the spiral arms of our Galaxy. During the journey, Earth travels through different regions, encountering stars and different densities of the interstellar medium. It experiences gravitational interactions with nearby stars and nebula sometimes exerting  subtle interactions. Regardless of the immense journey, the stars of our Galaxy remain relatively unchanged over a human lifetime. 

The Milky Way is a spiral galaxy with several prominent arms containing stellar nurseries swathed in pink clouds of hydrogen gas. The sun is shown near the bottom in the Orion Spur. Credit: NASA

A team of astronomers let by Jess A. Miller from the Department of Astronomy of Boston University have traced the path of the Sun back through time. In doing so, they have identified two occasions when the Earth and Solar System passed through two dense interstellar clouds. One of the crossings occurred 2 million years ago, the other 7 million years ago. Exploring the properties of the clouds, the team assert that the clouds are dense enough that they could compress the solar wind to inside the orbit of Earth. 

The Solar Wind is a constant stream of charged particles, mostly electrons and protons that are emitted from the upper layer of the Sun’s atmosphere, the corona. The particles travel through the Solar System at speeds between 400 and 800 kilometres per second. The edge of our Solar System is defined as the point where the solar wind merges with the interstellar medium.

A composite image comprised of the Sun’s surface, corona, and digitally-added coronal loops rendered by Andrew McCarthy. (Credit: Andrew McCarthy)

Previous teams have analysed climate change events due to these interstellar medium interactions with similar findings. Global cooling has been the result with an ice age being triggered. The study by Miller and team have readdressed this very topic using modern technology and processes. 

The team find that the interactions have indeed played a part in changes to the atmosphere of Earth. They find that levels of hydrogen in the upper atmosphere would have increased substantially. The newly acquired hydrogen would be converted to water molecules in the lower atmosphere and it would also have led to a reduction in mesospheric levels of ozone. These processes would have led to the appearance of global noctilucent clouds in the mesosphere. They would not have been permanent but may have blocked 7% of sunlight from reaching Earth, plunging our planet into an ice age.

Source : Earth’s Mesosphere During Possible Encounters With Massive Interstellar Clouds 2 and 7 Million Years Ago

The post What Happens to the Climate When Earth Passes Through Interstellar Clouds? appeared first on Universe Today.

The Sun. It’s that ongoing thermonuclear explosion that’s happening right over there. Although the Sun is necessary for life on Earth, we still have questions. So NASA has sent the Parker Solar Probe to visit the Sun, up close to get some questions answered.

The post #727 The Parker Solar Probe appeared first on Astronomy Cast.

SpaceX has retrieved from the sea the first-stage booster that flew on its latest Starship test flight, which launched this past June.

Earth’s last half-billion years were action-packed. During that time, the climate underwent many changes. There have been changes in ocean levels and ice sheets, changes in the atmosphere’s composition, changes in ocean chemistry, and ongoing biological evolution punctuated with extinction events.

A record of Earth’s temperature over the last 485 million years is helping scientists understand how it all played out and illustrating what could happen if we continue to enrich the atmosphere with carbon.

The new temperature record is presented in research titled “A 485-million-year history of Earth’s surface temperature.” It’s published in Science, and the lead author is Emily Judd. Judd is from the Department of Paleobiology at the Smithsonian National Museum of Natural History.

“This research illustrates clearly that carbon dioxide is the dominant control on global temperatures across geological time.”

Jessica Tierney, University of Arizona

The new historical temperature comes from an effort named PhanDA, which stands for Phanerozoic Data Assimilation. PhanDA combined data from climate models with data from geology to determine how the climate has changed over the last nearly 500 million years. The Phanerozoic is Earth’s current geological eon, and it started 538.8 million years ago. It’s known for the proliferation of life, and its beginning is marked by the appearance of the hard shells of animals in the fossil record.

PhanDA is a mix of data and prior simulations by the scientific community. “This approach leverages the strengths of both proxies and models as sources of information, providing an innovative way to explore the temporal and spatial patterns in Earth’s climate across the Phanerozoic,” the researchers write in their paper. It allowed the researchers to reconstruct the climate more thoroughly.

This figure illustrates the data used to create PhanDA. A shows the temporal distribution of proxy data used in PhanDA. B shows the spatial distribution. C shows the range (gray band) and median (black line) of GMSTs within the prior model ensemble for each assimilated stage. Image Credit: Judd et al. 2024.

“This method was originally developed for weather forecasting,” said Judd. “Instead of using it to forecast future weather, here we’re using it to hindcast ancient climates.”

We’re blowing by atmospheric carbon benchmarks, and the Earth is warming. We’re now at over 420 ppm of CO2. The best way to understand what’s coming our way is by looking at the past.

“If you’re studying the past couple of million years, you won’t find anything that looks like what we expect in 2100 or 2500,” said co-author Scott Wing, the curator of paleobotany at the National Museum of Natural History. Wing’s research focuses on the Paleocene–Eocene Thermal Maximum, a period of dramatic global warming 55 million years ago. “You need to go back even further to periods when the Earth was really warm, because that’s the only way we’re going to get a better understanding of how the climate might change in the future.”

During the Paleocene-Eocene Thermal Maximum (PETM), a massive amount of carbon was emitted into the atmosphere and the oceans. The Earth’s temperature reacted swiftly, warming by between five and eight degrees Celsius in only a few thousand years. While a few thousand years might seem long compared to a human lifetime, it’s nearly instantaneous for the climate of an entire planet. It likely triggered the massive extinction of between 35% to 50% of benthic life. Fossils show that during this time, sub-tropical planets grew in the polar regions.

Many scientists think the PETM is the best analogue for what we’re facing today. No matter what we do with our emissions in the next several decades, much of the carbon humanity has released into the atmosphere since the Industrial Revolution will persist in the atmosphere for thousands of years.

Earth’s reconstructed Global Mean Surface Temperature for the past 485 million years. Blue rectangles show the maximum latitudinal ice extent, and orange dashed lines show the timing of the five major mass extinctions of the Phanerozoic. The five orange fishbone symbols mark mass extinctions. Image Credit: Judd et al. 2024.

PhanDA illustrates the unbreakable link between carbon and global warming. According to co-author Jessica Tierney, a paleoclimatologist at the University of Arizona, the link between the climate and carbon is undeniable. “This research illustrates clearly that carbon dioxide is the dominant control on global temperatures across geological time,” said Tierney. “When CO2 is low, the temperature is cold; when CO2 is high, the temperature is warm.”

While proof of the link between climate and carbon isn’t new, this long timeframe drives it home. “The consistency of this relationship is surprising because, on this timescale, we expect solar luminosity to influence climate,” the authors write. “We hypothesize that changes in planetary albedo and other greenhouse gases (e.g., methane) helped compensate for the increasing solar luminosity through time.”

Overall, Earth’s global mean surface temperature (GMST) ranged from 11° to 36°C during the Phanerozoic, a larger range than previously thought. It also shows that greenhouse climates were hotter than thought. The largest temperature swings were in the high latitudes, but tropical temperatures ranged from 22 C to 42 C. This goes against the idea that the tropics have a fixed upper limit and shows that life must have evolved to survive in those higher temperatures.

The research also shows that our current climate is actually cooler than the climate through most of the Phanerozoic. Technically, Earth is in an ice age right now, though the ice is receding and has been for thousands of years. Earth’s current GMST is 15 Celsius, lower than during most of the Phanerozoic.

But while that may sound comforting, it’s not. It’s the rate of change in the GMST that’s dangerous. Our GHG emissions are warming the planet faster than at any time during the Phanerozoic.

“Humans, and the species we share the planet with, are adapted to a cold climate,” Tierney said. “Rapidly putting us all into a warmer climate is a dangerous thing to do.”

This figure from the published research shows the climate states through the Phanerozoic. D shows the latitudinal surface air temperature gradient associated with each of the climate states. Coloured bands show the 16th to 84th percentiles, and coloured lines show the median value. Image Credit: Judd et al. 2024.

While PhanDA is generally in agreement with previous climate reconstructions, it deviates in some ways. For example, cold climate periods don’t always coincide with glaciation and ice ages. Earth’s surface is ever-changing, and that can make some conclusions difficult to reach. “Many of the traditional glacial indicators can have nonglacial origins, complicating the interpretation of the rock record, and limited outcrop of older rocks and poor age control can make it difficult to discern between isolated alpine glaciers and widespread ice sheets,” the authors explain.

But that doesn’t take much away from PhanDA. It strengthens our understanding of climate and carbon.

This figure illustrates the undeniable relationship between atmospheric carbon and a warming climate. B shows PhanDA GMST versus CO2, colour-coded by geologic era. The black dashed line shows the York regression, a statistical method used to draw a straight line between data points with some uncertainties. C shows the CO2 ranges for each of the defined climate states. Image Credit: Judd et al. 024.

Shockingly, the work suggests that Earth’s climate is even more sensitive to CO2 than some current models show.

“PhanDA GMST exhibits a strong relationship with atmospheric CO2 concentrations, demonstrating that CO2 has been the dominant force controlling global climate variations across the Phanerozoic,” the authors write in their conclusion.

The post From Frozen to Sweltering: Earth’s Climate Over the Last 485 Million Years appeared first on Universe Today.

NASA astronaut Tracy C. Dyson is seen smiling and holding a gifted matryoshka doll outside the Soyuz MS-25 spacecraft after she landed with Roscosmos cosmonauts Oleg Kononenko and Nikolai Chub, in a remote area near the town of Zhezkazgan, Kazakhstan on Monday, Sept. 23, 2024. Dyson is returning to Earth after logging 184 days in space as a member of Expeditions 70-71 aboard the International Space Station and Chub and Kononenko return after having spent the last 374 days in space.

China launched separate sets of Earth-observation and "Internet of Things" satellites into orbit on Friday (Sept. 20) on two different missions.

Scientists have found nuclear weapons could actually help deflect an incoming cosmic impact — not by blowing an asteroid up, but by showering it with X-ray radiation.

Archaeologists have used AI to discover hundreds of large-scale drawings depicting figures like llamas, decapitated human heads and killer whales armed with knives

Archaeologists have used AI to discover hundreds of large-scale drawings depicting figures like llamas, decapitated human heads and killer whales armed with knives

Cosmic clouds form

NASA's Perseverance Mars rover will soon arrive at its first stop during its arduous trek to the western edge of Jezero Crater.

The astronauts and Crew Dragon capsule that will fly SpaceX's Crew-9 mission to the ISS have made it to Florida's Space Coast for their planned Sept. 26 liftoff.