Meeting Mercury at Dusk in July

mercury
The Moon, Venus and Mercury from 2022. Credit: Rob Sparks

Mercury puts on one of its best apparitions for 2024 this month.

Where have all of the planets gone? The late evening fall of dusk in early July also sees a sky seemingly vacant of familiar naked eye planets. Mars, Jupiter and Saturn are now denizens of dawn, and will stay that way for most of the remainder of 2024.

But two challenging planets are now emerging low to the west at dusk: Mercury and Venus. The two interior worlds are now mounting a slow return, as the hunt is now on the recover the two after sunset.

Continue reading “Meeting Mercury at Dusk in July”

Plate Tectonics Might Only Occur on 0.003% of Planets. That Makes Earth Very Special Indeed.

Plate tectonics: Image Credit: NASA/Goddard Space Flight Center Scientific Visualization Studio

Plate tectonics, oceans, and continents might just be the secret ingredients for complex life on Earth. And if these geological features are rare elsewhere in the universe, then perhaps that explains why we haven’t yet discovered intelligent alien life. New research from American and Swiss Earth scientists suggests that these ingredients represent missing variables in the famous Drake equation, devised more than half a century ago to estimate the chances of finding advanced civilizations in our galaxy. Including these new variables could completely rewrite the probability of detecting intelligent life in the Milky Way.

Continue reading “Plate Tectonics Might Only Occur on 0.003% of Planets. That Makes Earth Very Special Indeed.”

Merging Galaxies Make for Explosive Star Formation

A festive array of bright pinks and blues makes for a remarkable sight in this image captured with the Gemini North telescope, one half of the International Gemini Observatory. Resembling a cloud of cosmic confetti, this image is being released in celebration of Gemini North’s 25th anniversary. NGC 4449 is a prime example of starburst activity caused by the interacting and mingling of galaxies as it slowly absorbs its smaller galactic neighbors.

The Gemini Observatory has unveiled a striking new image that shows star formation within the irregular galaxy NGC 4449. This galaxy is categorised as a “Magellanic-type” galaxy due to its similarities  with the Magellanic Clouds, although it is smaller in size. Surrounding NGC 4449 is a halo of smaller dwarf galaxies, two of which are currently merging with it. This merger is causing clouds of gas to collide, fuelling the surge in star formation observed in NGC 4449.

Continue reading “Merging Galaxies Make for Explosive Star Formation”

NASA Releases a New 3D Animation of the Lunar Gateway

A detailed 3D animation of NASA's Gateway space station, showcasing its modules and structural components from various angles against the backdrop of deep space. NASA/Bradley Reynolds, Alberto Bertolin

To get to the Moon, NASA is building a Lunar Gateway in orbit to facilitate easier access to the Moon. With construction beginning in 2028 as part of Artemis IV there will be an ongoing programme of enhancements and additions. NASA has now released a fabulous new 3D animation of the Lunar Gateway to showcase what the final Gateway will look like. It includes modules from partner nations and an Orion lunar landers dock to carry astronauts. 

Continue reading “NASA Releases a New 3D Animation of the Lunar Gateway”

These Three Neutron Stars Shouldn't Be So Cold

Artist's impression of a neutron star, with white/blue filaments are streaming out from its polar regions, representing magnetic field lines. Credit: ESA

Neutron stars are among the densest objects in the Universe, second only to black holes. Like black holes, neutron stars are what remains after a star reaches the end of its life cycle and undergoes gravitational collapse. This produces a massive explosion (a supernova), in which a star sheds its outer layers and leaves behind a super-compressed stellar remnant. In fact, scientists speculate that matter at the center of the star is compressed to the point that even atoms collapse and electrons merge with protons to create neutrons.

Traditionally, scientists have relied on the “Equation of State” – a theoretical model that describes the state of matter under a given set of physical conditions – to understand what physical processes can occur inside a neutron star. But when a team led by scientists from the Spanish National Research Council (CSIC) examined three exceptionally young neutron stars, they noticed they were 10-100 times colder than other neutron stars of the same age. For this, the researchers concluded that these three stars are inconsistent with most of the proposed equations of state.

Continue reading “These Three Neutron Stars Shouldn't Be So Cold”

Existing Telescopes Could Directly Observe ‘ExoEarths…’ with a Few Tweaks

VLT
The four 8.2-metre Unit Telescopes of the Very Large Telescope at the Paranal Observatory complex. ESO/VLT

One proposal offers a unique method to directly image ExoEarths, or rocky worlds around nearby stars.

It’s the holy grail of modern exoplanet astronomy. As of writing this, the count of known worlds beyond the solar system stands at 6,520. Most of these are ‘hot Jupiters,’ large worlds in tight orbits around their host star. But what we’d really like to get a look at are ‘ExoEarths,’ rocky worlds (hopefully) like our own.

Continue reading “Existing Telescopes Could Directly Observe ‘ExoEarths…’ with a Few Tweaks”

Cepheid Variables are the Bedrock of the Cosmic Distance Ladder. Astronomers are Trying to Understand them Better

One of the brightest Cepheid variable stars, RS Puppis. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)-Hubble/Europe Collaboration
One of the brightest Cepheid variable stars, RS Puppis. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)-Hubble/Europe Collaboration

One of the most fundamental questions astronomers ask about an object is “What’s its distance?” For very faraway objects, they use classical Cepheid variable stars as “distance rulers”. Astronomers call these pulsating stars “standard candles”. Now there’s a whole team of them precisely clocking their speeds along our line of sight.

Continue reading “Cepheid Variables are the Bedrock of the Cosmic Distance Ladder. Astronomers are Trying to Understand them Better”

How Commercial Satellites Could Track Spy Balloons and Other UFOs

Chinese spy balloon tracked on satellite imagery
Crosses indicate the apparent position of a spy balloon over Missouri as seen in different spectral bands. (Credit: Planet Labs / Keto and Watters)

It turns out that you don’t need the Men in Black to spot unidentified anomalous phenomena, which are also known as UAPs, unidentified flying objects or UFOs. Researchers have shown how the task of detecting aerial objects in motion could be done by analyzing Earth imagery from commercial satellites.

They say they demonstrated the technique using one of the most notorious UAP incidents of recent times: last year’s flight of a Chinese spy balloon over the U.S., which ended in a shootdown by an Air Force fighter jet above the Atlantic Ocean. They also analyzed imagery of a different spy balloon that passed over Colombia at about the same time.

“Our proposed method appears to be successful and allows the measurement of the apparent velocity of moving objects,” the researchers report.

Continue reading “How Commercial Satellites Could Track Spy Balloons and Other UFOs”

Do We Now Have an Accurate Map of Nearby Stars?

This image shows the bright stars within 15 parsecs of the Sun. If red dwarfs and brown dwarfs were included, there would be far more stars. But those stars are difficult to spot. Have we found all of them yet? Image Credit: By Andrew Z. Colvin - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=14359465

If the Sun has a stellar neighbourhood, it can be usefully defined as a 20 parsec (65 light-years) sphere centred on our star. Astronomers have been actively cataloguing the stellar population in the neighbourhood for decades, but it hasn’t been easy since many stars are small and dim.

Even with all of the challenges inherent in the effort, astronomers have made steady progress. Do we now have a complete catalogue?

Continue reading “Do We Now Have an Accurate Map of Nearby Stars?”

Simulating the Last Moments Before Neutron Stars Merge

Volume rendering of density in a simulation of a binary neutron star merger. New research shows that neutrinos created in the hot interface between the merging stars can be briefly trapped and remain out of equilibrium with the cold cores of the merging stars for 2 to 3 milliseconds. Credit: David Radice/Penn State

When stars reach the end of their life cycle, they shed their outer layers in a supernova. What is left behind is a neutron star, a stellar remnant that is incredibly dense despite being relatively small and cold. When this happens in binary systems, the resulting neutron stars will eventually spiral inward and collide. When they finally merge, the process triggers the release of gravitational waves and can lead to the formation of a black hole. But what happens as the neutron stars begin merging, right down to the quantum level, is something scientists are eager to learn more about.

When the stars begin to merge, very high temperatures are generated, creating “hot neutrinos” that remain out of equilibrium with the cold cores of the merging stars. Ordinarily, these tiny, massless particles only interact with normal matter via weak nuclear forces and possibly gravity. However, according to new simulations led by Penn State University (PSU) physicists, these neutrinos can weakly interact with normal matter during this time. These findings could lead to new insights into these powerful events.

Continue reading “Simulating the Last Moments Before Neutron Stars Merge”