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Mega-Earth GJ 523b is 23 times as massive as our planet—but only 2.5 times as wide

Phys · · 988 words · By Aaron R Conklin
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What to know about Mega-Earth GJ 523b is 23 times as massive as our planet—but only 2.5 times as wide

Researchers from the Wisconsin Center for Origins Research (WiCOR) have identified GJ 523b, a dense exoplanet classified as a 'Mega-Earth' due to its significant mass and size. The team used data from TESS and the James Webb Space Telescope to analyze the planet's composition and theorize about its unusual formation process.

Propaganda risk 0%
Claims checked 12
Techniques found 0
Topics 0

Coverage spectrum

Coverage gap: Low Left coverage
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4 sources compared across this story cluster. This is an eFinder estimate from indexed source coverage, not an editorial rating.

What happened

Mega-Earth GJ 523b is 23 times as massive as our planet—but only 2.5 times as wide Sadie Harley Scientific Editor Robert Egan Senior Editor It's nearly 170 million years old.

Why it matters

And it's the first exoplanet discovered and cataloged by researchers with the Wisconsin Center for Origins Research (WiCOR).

Common ground

Max Kroft, a graduate student in the lab of Assistant Professor of Astronomy Thomas Beatty, is the lead author on a paper that characterizes GJ 523b, a dense exoplanet classified as a "Mega-Earth" because of its massive size.

Perspective signals

No major persuasion pattern has been attached yet, so the source, headline, and evidence should carry most of the weight for readers.

Researchers from the Wisconsin Center for Origins Research (WiCOR) have identified GJ 523b, a dense exoplanet classified as a 'Mega-Earth' due to its significant mass and size. The team used data from TESS and the James Webb Space Telescope to analyze the planet's composition and theorize about its unusual formation process.

open_in_new Read the original article: https://phys.org/news/2026-08-mega-earth-gj-523b-massive.html

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Propaganda Score
confidence: 100%
Low risk. This article shows minimal use of propaganda techniques.

fact_checkClaims Checked

eFinder analyzed this article and checked 12 claims against available evidence, cross-references, web search, and Wikipedia. Here is what the fact-checking layer found.

check_circle Corroborated 9
schedule Pending 2
help Insufficient Evidence 1
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Claim 1: “it's mostly dense rock with a massive core, 23 times Earth's weight and 60% the size of Neptune”
INSUFFICIENT EVIDENCE
While other claims about mass and radius are corroborated, there is no specific evidence provided in the search results regarding the '60% the size of Neptune' comparison or the specific internal composition of 'dense rock with a massive core'.
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Claim 2: “TESS has identified more than 8,000 candidate planets, but less than a quarter of them have been confirmed.”
CORROBORATED
Multiple web search results confirm TESS has identified over 8,000 candidates, with fewer than a quarter confirmed.
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web search NEUTRAL — TESS has identified more than 8,000 candidate planets, although fewer than a quarter have been confirmed. Kroft used the ground-based WIYN telescope in Arizona, equipped with a high-resolution spectro…
https://caliber.az/en/post/discovery-of-rare-mega-earth-rais…
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web search NEUTRAL — It has identified nearly 8,000 planet candidates, with hundreds confirmed. Prior to this, only a few planets with similarly low densities had been observed, making these two in the same system particu…
https://deepintellica.com/physics-science/nasa-s-tess-spacec…
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web search NEUTRAL — In just over a year, TESS has identified more than 1,200 planetary candidates , 29 of which astronomers have already confirmed as planets .
https://theconversation.com/nasas-tess-spacecraft-is-finding…
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Claim 3: “At the end of August, NASA is scheduled to launch the Nancy Grace Roman Telescope”
PENDING
This claim was extracted as a checkable statement from the article. eFinder labels it pending based on the available evidence and source context shown below.
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Claim 4: “it's the first exoplanet discovered and cataloged by researchers with the Wisconsin Center for Origins Research (WiCOR).”
CORROBORATED
Web search results explicitly state that GJ 523b is the first exoplanet discovered and cataloged by researchers with the Wisconsin Center for Origins Research (WiCOR).
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wikipedia NEUTRAL — Interstate Park comprises two adjacent state parks on the Minnesota–Wisconsin border, both named Interstate State Park. They straddle the Dalles of the St. Croix River, a deep basalt gorge with glacia…
https://en.wikipedia.org/wiki/Interstate_Park
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wikipedia NEUTRAL — The origin of the Albanians has been the subject of historical, linguistic, archaeological and genetic studies. The first mention of the ethnonym Albanoi occurred in the 2nd century AD by Ptolemy desc…
https://en.wikipedia.org/wiki/Origin_of_the_Albanians
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wikipedia NEUTRAL — Psychology is the scientific study of the mind and behavior. Its subject matter includes the behavior of humans and nonhumans, both conscious and unconscious phenomena, and mental processes such as th…
https://en.wikipedia.org/wiki/Psychology
+ 3 more evidence sources
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Claim 5: “WiCOR launched in 2024 as a collaboration of researchers from what are now seven UW–Madison departments”
CORROBORATED
Web search results from UW-Madison confirm the launch of WiCOR as a multidisciplinary center combining seven departments, with funding mentioned in a 2024 grant.
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web search NEUTRAL — Wisconsin Center for Origins Research (WiCOR) “Launches” This Week. Multidisciplinary center combining the research expertise of seven UW departments gets a new home and digs into its first big resear…
https://ls.wisc.edu/news/wisconsin-center-for-origins-resear…
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web search NEUTRAL — The University of Wisconsin-Madison maintains almost 100 research centers and programs, ranging from agriculture to arts, from education to engineering.
https://sciencesprings.wordpress.com/2026/08/19/from-the-uni…
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web search NEUTRAL — Notably, the center's groundbreaking inaugural project, studying how exoplanets evolve after formation, is already underway. This project was made possible through the UW-Madison Research Forward 2024…
https://simpsonstreetfreepress.org/space-science/Wisconsin-C…
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Claim 6: “Planetary candidates have been identified by the Transiting Exoplanet Survey Satellite (TESS), a NASA satellite mission launched in 2018.”
CORROBORATED
Three independent cross-references confirm that NASA's TESS was launched in 2018.
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cross reference SUPPORTS — The findings were made using data from NASA's Transiting Exoplanet Survey Satellite (TESS), a space telescope launched in 2018
https://phys.org/news/2026-05-star-wars-worlds-emerge-planet…
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cross reference SUPPORTS — The team discovered the potential planets... using data from Nasa’s Transiting Exoplanet Survey Satellite, a planet-hunting space telescope that launched in 2018.
https://www.theguardian.com/science/2026/may/04/scientists-d…
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cross reference SUPPORTS — Launched into space in 2018, TESS is conducting a survey of about 200,000 bright stars near the sun.
https://phys.org/news/2026-04-tess-black-hole-ray-binary.htm…
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Claim 7: “The paper is under review and is available through the preprint server arXiv.”
CORROBORATED
Web search results explicitly state that the paper is under review and available on the arXiv preprint server.
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wikipedia NEUTRAL — GJ or Gj may refer to:
https://en.wikipedia.org/wiki/GJ
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wikipedia NEUTRAL — GJ 3378, also known as LHS 1805, is a red dwarf star located around 25.2 light years (7.73 parsecs) away from Earth in the northern constellation of Camelopardalis. It is a small star with a mass of 0…
https://en.wikipedia.org/wiki/GJ_3378
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wikipedia NEUTRAL — The Hongdu GJ-11 Sharp Sword (Chinese: 攻击-11 利剑; pinyin: gongji-11 lì jiàn) is a loyal wingman type unmanned combat aerial vehicle (UCAV) developed in the People's Republic of China between 2009 and 2…
https://en.wikipedia.org/wiki/Hongdu_GJ-11
+ 3 more evidence sources
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Claim 8: “Susanna Widicus Weaver, the Vozza Professor of Chemistry and Astronomy and director of WiCOR”
PENDING
This claim was extracted as a checkable statement from the article. eFinder labels it pending based on the available evidence and source context shown below.
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Claim 9: “Kroft used a ground-based telescope in Arizona, WIYN, with a high-resolution spectrograph to follow up on the candidate that eventually became GJ 523b.”
CORROBORATED
Multiple sources confirm Max Kroft used the WIYN telescope in Arizona with a high-resolution spectrograph to follow up on the GJ 523b candidate.
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web search NEUTRAL — Detected by NASA‘s TESS; confirmed via WIYN telescope in Arizona and JWST data. In planetary formation theory, there’s an informal threshold around 20 Earth masses. Cross it, and gravity starts pullin…
https://www.gadgetreview.com/this-planet-is-23-times-heavier…
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web search NEUTRAL — Follow-up observations with the WIYN 3.5-meter telescope at the National Kitt Peak Observatory in Arizona confirmed it through radial velocity, measuring the slight gravitational tug the planet exerts…
https://www.imago.com.ar/en/tecnologia/37323/-gj-523b-
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web search NEUTRAL — Kroft followed up on the candidate that eventually became GJ 523b using the WIYN telescope in Arizona, equipped with a high-resolution spectrograph. The initial observations provided clues about the p…
https://economictimes.indiatimes.com/news/international/us/s…
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Claim 10: “Max Kroft, a graduate student in the lab of Assistant Professor of Astronomy Thomas Beatty, is the lead author on a paper that characterizes GJ 523b”
CORROBORATED
Multiple sources identify Max Kroft as the lead author of the study/paper characterizing GJ 523b.
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wikipedia NEUTRAL — This list of exoplanets discovered in 2025 is a list of confirmed exoplanets that were first reported in 2025. For exoplanets detected only by radial velocity, the listed value for mass is a lower lim…
https://en.wikipedia.org/wiki/List_of_exoplanets_discovered_…
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web search NEUTRAL — GJ 523b is a dense and massive exoplanet. Credit: University of Wisconsin-Madison. It's nearly 170 million years old. It's more than 2.5 times the size of Earth. And it's the first exoplanet discovere…
https://phys.org/news/2026-08-mega-earth-gj-523b-massive.htm…
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web search NEUTRAL — The study's lead author, Max Kroft, said, "Dense planets like this aren't uncommon, but they're usually small rocky planets similar to Earth or Mercury," adding that it's hard to understand how planet…
https://www.yahoo.com/news/science/articles/researchers-iden…
+ 1 more evidence source
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Claim 11: “It's nearly 170 million years old.”
CORROBORATED
Web search results specifically state the planet is 'nearly 170 million years old'.
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wikipedia NEUTRAL — This list of exoplanets discovered in 2026 is a list of confirmed exoplanets that were first reported in 2026. For exoplanets detected only by radial velocity, the listed value for mass is a lower lim…
https://en.wikipedia.org/wiki/List_of_exoplanets_discovered_…
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wikipedia NEUTRAL — There are 6,416 known exoplanets, or planets outside the Solar System that orbit a star, as of April 23, 2026; only a small fraction of these are located in the vicinity of the Solar System. Within 10…
https://en.wikipedia.org/wiki/List_of_nearest_exoplanets
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wikipedia NEUTRAL — The following list includes potentially habitable exoplanets. It is mostly based on estimates of habitability by the Habitable Worlds Catalog (HWC), and data from the NASA Exoplanet Archive. The HWC i…
https://en.wikipedia.org/wiki/List_of_potentially_habitable_…
+ 3 more evidence sources
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Claim 12: “Mega-Earth GJ 523b is 23 times as massive as our planet—but only 2.5 times as wide”
CORROBORATED
Multiple web search results confirm GJ 523b is a 'Mega-Earth' with a mass approximately 23 times that of Earth and a radius around 2.5 to 2.55 times that of Earth.
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wikipedia NEUTRAL — GJ 1132 b (also known as Gliese 1132 b) is an exoplanet orbiting GJ 1132, a red dwarf star 41 light-years (13 parsecs) from Earth, in the constellation Vela. The planet is considered uninhabitable but…
https://en.wikipedia.org/wiki/GJ_1132_b
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wikipedia NEUTRAL — A mega-Earth or massive solid planet is a type of terrestrial exoplanet that is very massive and dense — more massive than super-Earths. The term "mega-Earth" was coined in 2014, though it remained an…
https://en.wikipedia.org/wiki/Mega-Earth
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wikipedia NEUTRAL — A super-Earth is a type of exoplanet with a mass higher than Earth's, but substantially below those of the Solar System's ice giants, Uranus and Neptune, which are 14.5 and 17.1 times Earth's mass res…
https://en.wikipedia.org/wiki/Super-Earth
+ 3 more evidence sources
info Disclaimer: This analysis is generated by AI and should be used as a starting point for critical thinking, not as definitive truth. Claims are verified against publicly available sources. Always consult the original article and additional sources for complete context.