Universe Today

September 7, 2024September 7, 2024 by Jon Voisey

Why Did Copernicus Reject Geocentrism?

Astronomer Copernicus, or Conversations with God, by Matejko. Credit: frombork.art.pl/pl/

Popular science history paints a picture of the Greek geocentric model dominating astronomical thought beginning around the 3rd century BCE, and being the favored model for ~1,500 years. Then, suddenly (it suggests), astronomical thought was overhauled at the birth of the Renaissance by brilliant astronomers such as Copernicus, Kepler, and Galileo, all of whom rejected placing the Earth at the center of the cosmos.

But these sources are generally quiet on why this shift occurred. If mentioned at all, sources generally suggest that it was because the Ptolemaic geocentric model was too complicated – overly burdened with epicycle and equants. Heliocentrism, in comparison, was simple – elegant, even.

Yet, Copernicus’ heliocentric model was still rooted in the Greek philosophical principles of uniform circular motion. Thus, it too was forced to adopt many of the complications we’re regularly told were the reason for rejecting Ptolemy’s model – epicycles included.

So, why then, did Copernicus actually turn his back on over 1,500 years of astronomical thought?

The answers are an interesting glimpse into the astronomical paradigm of the 16th century.

September 7, 2024September 7, 2024 by Nancy Atkinson

China Will Launch its Mars Sample Return Mission in 2028

The launch of the Tianwen-1 mission, Wenchang City, south China's Hainan Province, July 23, 2020. /CFP

While NASA’s Mars Sample Return mission has experienced a setback, China is still moving forward with their plans to bring home a piece of the Red Planet. This week, officials from the China National Space Administration (CNSA) announced their sample return mission, called Tianwen-3, will blast off for Mars in 2028. It will land on the surface, retrieve a sample, and then take off again, docking with a return vehicle in orbit. They also announced another mission, Tianwen-4 will head off to Jupiter in 2030 as well as unveiling a conceptual plan for China’s first mission to test defenses against a near-Earth asteroid.

The announcements were made this week at the second International Deep Space Exploration Conference, also known as the Tiandu Forum, held in China. China says the conference promotes international cooperation for future large-scale missions.

September 7, 2024September 7, 2024 by Laurence Tognetti

Artemis III Landing Sites Identified Using Mapping and Algorithm Techniques

Rendition of the 13 candidate landing site regions for NASA’s Artemis III mission, with each region measuring approximately 15 by 15 kilometers (9.3 by 9.3 miles). Final landing sites within those regions measure approximately 200 meters (656 feet) across. (Credit: NASA)

Where would be the most ideal landing site for the Artemis III crew in SpaceX’s Human Landing System (HLS)? This is what a recent study submitted to Acta Astronautica hopes to address as an international team of scientists investigated plausible landing sites within the lunar south pole region, which comes after NASA selected 13 candidate landing regions in August 2022 and holds the potential to enable new methods in determining landing sites for future missions, as well.

September 6, 2024September 6, 2024 by Evan Gough

One Step Closer to Solving the Mystery of Mars’ Lost Water

NASA scientists have determined that a primitive ocean on Mars held more water than Earth's Arctic Ocean and that the Red Planet has lost 87 percent of that water to space. Credit: NASA/GSFC

Few scientists doubt that Mars was once warm and wet. The evidence for a warm, watery past keeps accumulating, and even healthy skepticism can’t dismiss it. All this evidence begs the next question: what happened to it?

September 6, 2024September 6, 2024 by Evan Gough

JWST Reveals Star Formation at Cosmic Noon

A massive galaxy cluster named MACS-J0417.5-1154 is warping and distorting the appearance of galaxies behind it, an effect known as gravitational lensing. This natural phenomenon magnifies distant galaxies and can also make them appear in an image multiple times, as NASA’s James Webb Space Telescope saw here. Two distant, interacting galaxies — a face-on spiral and a dusty red galaxy seen from the side — appear multiple times, tracing a familiar shape across the sky. NASA, ESA, CSA, STScI, V. Estrada-Carpenter (Saint Mary's University).

Understanding the star formation rate (SFR) in a galaxy is critical to understanding the galaxy itself. Some galaxies are starburst galaxies with extremely high SFRs, some are quenched or quiescent galaxies with very low SFRs, and some are in the middle. Researchers used the JWST to observe a pair of galaxies at Cosmic Noon that are just beginning to merge to see how SFRs vary in different regions of both galaxies.

September 5, 2024September 5, 2024 by Nancy Atkinson

The Final Vega Rocket Blasts Off

The launch of a Vega rocket from the European Spaceport in French Guiana, as seen from the Bois Dable Lake on April 9, 2024. Credit: ESA/ArianeGroup/Arianespace/CNES

The European Space Agency (ESA) launched its final Vega rocket this week, lofting a Sentinel-2C Earth observation satellite into orbit. This wraps up 12 years of service and 20 successful flights for the venerable Vega. The rocket launched several well-known missions, including LISA Pathfinder (2015), the Earth-observing satellites Proba-V (2013), and Aeolus (2018). ESA will now launch these types of payloads on the new Vega-C rocket, capable of launching heavier payloads at a lower price.

Vega’s final launch was on September 5, 2024 from Europe’s Spaceport in French Guiana, and ESA said that it was fitting the rocket boosted to orbit one of the Sentinel satellites, as Vega had previously launched Sentinel-2A in 2015 and Sentinel-2B in 2017.

September 5, 2024September 9, 2024 by Matt Williams

Ouch! A Monster Asteroid Crashed Into Ganymede 4 Billion Years Ago, Rolling it Over

Artist's impression of the large impact that caused Ganymede to reorient itself 4 billion years ago. © HIRATA Naoyuki

Jupiter’s moon, Ganymede, is a fascinating celestial body. Measuring 5,268 km (3,272 mi) in diameter, it is also the largest satellite in the Solar System and even larger than Mercury, which measures 4,880 km (3,032 mi) in diameter. Like Europa, it has an interior ocean and is one of the few bodies in the Solar System (other than the gas giants) with an intrinsic magnetic field. The presence of this field also means Ganymede experiences aurorae circling the regions around its northern and southern poles due to interaction with Jupiter’s magnetic field.

In addition, based on its surface craters, scientists believe that Ganymede experienced a powerful impact with an asteroid about 4 billion years ago. This asteroid was about 20 times larger than the Chicxulub asteroid that caused the extinction of the dinosaurs, or the Cretaceous–Paleogene extinction event (ca. 66 million years ago). According to a recent study by Naoyuki Hirata of Kobe University, this impact occurred almost precisely on the meridian farthest away from Jupiter. This caused a reorientation of Ganymede’s rotational axis and allowed Hirata to determine exactly what type of impact took place.

September 5, 2024September 5, 2024 by Mark Thompson

NASA’s Putting its Solar Sail Through its Paces

Those of you following the Advanced Composite Solar Sail System may have heard that its booms and sail are now deployed. It is receiving light pressure from the Sun to propel it through the Solar System. Like a test pilot in a new aircraft, NASA are now testing out just how it handles. Before deployment, the spacecraft was slowly tumbling and now the controllers will see if they can get it under control and under sail power. The reflectivity of the sail means its an easy spot in the night sky, just fire up the NASA app to find out where to look.

September 5, 2024September 5, 2024 by Matt Williams

There are Important Differences Between the Ice Caps on Mars

This image shows eroded channels near the Martian poles filled with bright frozen carbon dioxide, in contrast to the muted red of the underlying ground. Credit:NASA/JPL/University of Arizona

In the 17th century, astronomers Giovanni Domenica Cassini and Christian Huygens noted the presence of hazy white caps while studying the Martian polar regions. These findings confirmed that Mars had ice caps in both polar regions, similar to Earth. By the 18th century, astronomers began to notice how the size of these poles varied depending on where Mars was in its orbital cycle. Along with discovering that Mars’ axis was tilted like Earth’s, astronomers realized that Mars’ polar ice caps underwent seasonal changes, much like Earth’s.

While scientists have been aware that Mars’ polar ice caps change with the seasons, it has only been within the last 50 years that they have realized that they are largely composed of frozen carbon dioxide (aka. “dry ice”) that cycles in and out of the atmosphere – and questions as to how this happens remain. In a recent study, a team of researchers led by the Planetary Science Institute (PSI) synthesized decades of research with more recent observations of the poles. From this, they determined how the Martian poles differ in terms of their seasonal accumulation and release of atmospheric carbon dioxide.

September 5, 2024September 5, 2024 by Evan Gough

Archaeological Methods Reveal How Astronauts Work on the International Space Station

Archaeology is the study of human prehistory, so it seems incongruous to use its methods to study how humans behave in space. But that’s what astronauts aboard the International Space Station are doing.