Tag Archives: smaller

New Juno Data Reveals Jupiter is Smaller and More ‘Squeezed’ Than Previously Thought

Posted on by
Reply

Here’s the rewritten content that is SEO optimized while preserving the necessary HTML tags:

Leveraging high-precision radio occultation measurements from NASA’s Juno mission, planetary scientists have significantly refined the shape of Jupiter. Their findings reveal that the planet’s polar, equatorial, and mean radii are smaller than earlier estimates from NASA’s Pioneer and Voyager missions, with substantially reduced uncertainty.

This vibrant visible-light image of Jupiter was captured using the Hubble Wide-Field Camera 3 on January 11, 2017. Featured prominently are the Great Red Spot and a long brown feature known as the “Brown Barge,” stretching approximately 72,000 km (around 45,000 miles) from east to west, with Red Spot Junior (Oval BA) on the lower right. Image credits: NASA / ESA / NOIRLab / NSF / AURA / Wong et al. / De Peyter et al. / M. Zamani.

“Jupiter, recognized as the largest planet in our solar system, is an almost oblate spheroid due to its rapid rotation of 9 hours, 55 minutes, and 29 seconds, causing a slight flattening at the poles and a bulge at the equator,” stated Dr. Eli Galanti of the Weizmann Institute of Science.

“This unique shape results from the gravitational forces pulling inward and centrifugal forces pushing outward from its rotation axis. Consequently, Jupiter’s equatorial radius is approximately 7% larger than its polar radius.”

“For celestial bodies with a uniform density, the shape is ideally ellipsoidal. However, Jupiter’s internal density varies significantly from the cloud layer of about 1 bar, where density is less than 1 kg/m3, to deeper layers reaching densities of several thousand kg/m3.”

“This density variation causes the planet’s shape to deviate from a simple ellipsoid by tens of kilometers, as reflected in fluctuations of the gravitational field across latitudes.”

“Additional alterations in Jupiter’s shape are induced by strong zonal winds detected at cloud level,” Dr. Galanti continued.

“These winds modify the centrifugal force, leading to variations of about 10 km mainly at lower latitudes.”

Historically, Jupiter’s dimensions were based on data from six radio occultation experiments conducted by NASA’s Pioneer and Voyager missions in the 1970s.

In this groundbreaking study, researchers reviewed radio occultation data collected during 13 close encounters between Juno and Jupiter, integrating the effects of zonal winds into their analysis.

“Radio occultation enables us to peer through Jupiter’s dense, opaque atmosphere to understand its internal structure,” the researchers elucidated.

“During the occultation experiment, Juno transmits radio signals to NASA’s Deep Space Network on Earth.”

“As these signals traverse Jupiter’s electrically charged ionosphere, they experience bending and delay.”

“By measuring the frequency changes caused by this bending, we can derive the temperature, pressure, and electron density at various atmospheric depths.”

The research concluded that Jupiter is approximately 8 km narrower at its equator and 24 km flatter at its poles.

“Including the effects of zonal winds significantly diminishes uncertainty in our understanding of Jupiter’s shape,” the researchers noted.

“At a pressure level of 1 atmosphere, we’ve determined a polar radius of 66,842 km, an equatorial radius of 71,488 km, and a mean radius of 69,886 km, which are smaller by 12 km, 4 km, and 8 km than previously estimated, respectively.”

For more details, view the findings published in this week’s Nature Astronomy.

_____

E. Galanti et al. Jupiter’s Size and Shape. Nat Astron published online on February 2, 2026. doi: 10.1038/s41550-026-02777-x

This version maintains the original meaning but enhances keyword density and relevance for SEO while adhering to the provided HTML structure.

Source: www.sci.news

Jupiter: Smaller Than Anticipated and Facing Compression

Posted on by
Reply

Artistic representations of the Juno spacecraft above Jupiter’s Antarctic region

NASA/JPL-Caltech

Recent findings suggest Jupiter is not as large as previously believed, based on over four decades of radius measurements.

As a gas giant, Jupiter lacks a solid outer shell like Earth. Nevertheless, astronomers determine its shape by examining how the gas height varies around Earth at a consistent pressure level.

The most accurate measurements of this gas pressure level date back to NASA’s Voyager and Pioneer missions over 40 years ago. These spacecraft utilized radio waves to transmit signals through Jupiter’s atmosphere to Earth, allowing scientists to gather data and compute gas pressure at specific altitudes, employing a method known as radio occultation.

Currently, Eli Garanti from the Weizmann Institute of Science in Israel and his team have been measuring Jupiter’s radius since 2016, using radio occultation data obtained from NASA’s Juno spacecraft, which has been orbiting the gas giant since that year. They report that Jupiter’s average size is approximately 8 kilometers less than previously estimated, particularly at the poles.

“According to the Juno Radio occultation, Jupiter is smaller and more oblate, with a reduced size at the equator,” Garanti mentioned at the Europlanet Science Congress (EPSC) held in Helsinki, Finland on September 11.

Garanti and his team conducted 13 radio occultations with Juno, compared to the six combined by the Voyager and Pioneer missions, and calculated the diameter based on known wind speed measurements of Jupiter. For a pressure equivalent to one bar of gas (Earth’s sea-level atmospheric pressure), the planet’s diameter was measured to be 142,976 kilometers at the poles and 133,684 kilometers at the equator.

“Understanding the exact radius is essential, but it also aids in revealing the inner workings of the planet,” noted Oded Aharonson at the Weizmann Institute of Science, who did not participate in this study. “These new constraints will enable more accurate models of Jupiter’s interior, which are often complex and challenging to explore.”

topics:

Source: www.newscientist.com

Scientists discover new exoplanet near Barnard Star that is smaller than Earth

Posted on by
Reply

An exoplanet with at least half the mass of Venus orbits Barnard's Star, the closest single star to the Sun, once every 3.15 days.

Artist's impression of Bernard B. Image credit: ESO / M. Kornmesser.

Barnard's Star is a 10 billion year old red dwarf star located in the constellation Ophiuchus.

At a distance of about 6 light years, it is the second closest star to the Sun after the Alpha Centauri triple star system.

The star, also known as Gliese 699 or GJ 699, is much smaller than the Sun and is classified as an M3.5 dwarf.

Despite the prospect of a “super-Earth” with a mass 3.2 times that of Earth in 2018, no planets have ever been confirmed to orbit this star.

The new exoplanet discovery is the result of five years of observations using the ESPRESSO instrument of ESO's Very Large Telescope (VLT) at the Paranal Observatory in Chile.

“We were always confident that we would find something, even if it took a long time,” said Dr. Jonay González Hernández, an astronomer at the Canarias Astronomical Institute.

The newly discovered planet, named Barnard b, is about 20 times closer to Barnard's star than Mercury is to the Sun.

It orbits its parent star in 3.15 Earth days and has a surface temperature of about 125 degrees Celsius (257 degrees Fahrenheit).

“Bernard B is one of the lowest-mass exoplanets known, and one of the few exoplanets known to have less mass than Earth,” said Dr. González-Hernández. Ta.

“But this planet is too close to its host star, closer than the habitable zone.”

“Even though this star is about 2,500 degrees cooler than the Sun, it's still too hot to support liquid water on its surface.”

In addition to the confirmed planet, astronomers also discovered hints of three more exoplanet candidates orbiting the same star.

However, additional observations are required to confirm these candidates.

“We need to continue observing this star to confirm other candidate signals,” said Dr. Alejandro Suárez Mascareño, also from the Canarias Astronomical Institute and co-author of the study.

“But the discovery of this planet, along with previous discoveries such as Proxima b and Proxima d, shows that our cosmic backyard is full of low-mass planets.”

Bernard B's findings were published in a. paper in diary astronomy and astrophysics.

_____

JI Gonzalez Hernandez others. 2024. A sub-Earth mass planet orbiting Barnard's star. A&A 690, A79; doi: 10.1051/0004-6361/202451311

Source: www.sci.news

Light pollution may be causing urban moths to evolve smaller wings

Posted on by
Reply

Spindle ermine moth perched on a flower

DP Wildlife Invertebrates / Alamy

Moths trying to survive in bright cities may have evolved smaller wings to limit the amount of light they absorb.

Artificial lights that shine at night disrupt the lives of many insect species, diverting them from their habitats and mates, and exposing them to predators. Ecological changes due to light pollution may also have caused evolutionary changes, but clear examples are hard to find.

In search of such changes, evert van de shoot Researchers from the Catholic University of Leuven in Belgium analyzed the wing and body sizes of 680 spindle-shaped stoat moths.Yoponomeuta cañajera). These moths are previous experiment Test your reaction to light.

In their experiment, the researchers collected moth larvae from bright urban and dark rural locations in France and Switzerland and raised the moths together in the same garden. In the ‘flight to light’ test, urban moths were captured in 30 percent fewer light traps than rural moths, suggesting that they were less responsive to light.

Van de Schoot and his colleagues may have found an explanation for this. Careful measurements of the insects’ bodies revealed that moths in urban environments had slightly smaller wings on average than moths in rural areas. In both urban and rural populations, this small wing size correlated with a weak response in light trap experiments.

“What’s really surprising is that despite small changes in plumage, there are differences in rural and urban moth populations,” he says. Samuel Fabian At Imperial College London. He said the study’s focus on flight mechanics adds a new dimension to thinking about the effects of light on insects. “Nature is not static,” he says. “Nature adapts to us.”

Small wings can limit the distance and speed these moths can disperse to find mates and food. But if the trade-off makes moths less susceptible to the negative effects of being sensitive to light, it could be a beneficial adaptation in urban ecosystems, van de Scoot says.

The researchers say they cannot rule out the possibility that this change was driven by other differences between urban and rural areas, such as more fragmented habitats. Changes in visual acuity may also contribute to urban moths’ reduced response to light. Other insect species may also be affected differently.

But if such shifts in mobility were widespread, they could separate insect populations from each other and from the plants they pollinate, van de Scoot says. “It could be important for the entire ecosystem.”

topic:

Source: www.newscientist.com