trans-Neptunian object Archives

Artist’s conception of this research showing an imagined time sequence as a star passes behind a TNO with an atmosphere. (Credit: NAOJ)

Astrochemistry, Astrogeology, Atmospheres, Climate, Weather, Comets and Asteroids, Icy Worlds, Imaging & Spectroscopy, Pluto, Press Release

Trans-Neptunian Object (612533) 2002 XV93 Has An Atmosphere – But Shouldn’t

by Keith CowingMay 5, 2026May 5, 2026

A team of professional and amateur Japanese astronomers found evidence for a thin atmosphere around a small body in the outer Solar System. The object is so small that it […]

Dust surface density evolution in the fiducial model without disk buildup (left) and with disk buildup taken into account (right). Time zero refers to the moment the gas disk reaches maximum mass in the model including its buildup, corresponding to the time the dust is initialized in the model without disk buildup. -- astro-ph.EP

Astrogeology, Astronomy & Telescopes, Exoplanets, -moons, -comets, Icy Worlds, Imaging & Spectroscopy, Status Report

Dust Evolution During Protoplanetary Disk Bbuildup Enhances CO Ice Relative To Water

by Keith CowingApril 1, 2026April 1, 2026

Water ice is expected to be the dominant volatile component of bodies formed in the outer Solar System. However, recent observations of comets and trans-Neptunian objects suggest that the relative […]

3I spectrum (dots) and the reflectance spectra of three CR and one R chondrite discussed in the text. -- astro-ph.EP

Astrochemistry, Astrogeology, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Comets and Asteroids, Icy Worlds, Interstellar, Status Report

Spectrophotometric Evidence For A Metal-bearing, Carbonaceous, and Pristine Interstellar Comet 3I/ATLAS

by Keith CowingNovember 30, 2025November 30, 2025

3I/ATLAS is only the second confirmed cometary object known to enter the Solar System from interstellar space.

An SwRI-led team used Webb telescope observations (white) to detect methane gas on the distant dwarf planet Makemake. Sharp emission peaks near 3.3 microns reveal methane in the gas phase above Makemake’s surface. A continuum model (cyan) is overlaid for comparison; the gas emission peaks are identified where the observed spectrum rises above the continuum. An artistic rendering of Makemake’s surface is shown in the background. Courtesy of S. Protopapa, I. Wong/SwRI/STScI/NASA/ESA/CSA

Astrochemistry, Astrogeology, Biochemistry & Organic Chemistry, Comets and Asteroids, Icy Worlds, Imaging & Spectroscopy, Press Release

Methane Gas Discovered On Makemake

by Keith CowingSeptember 11, 2025

A Southwest Research Institute-led team has reported the first detection of gas on the distant dwarf planet Makemake, using NASA’s James Webb Space Telescope (JWST). This discovery makes Makemake only […]

Deep imaging (top) and polarimetric (bottom

Astrochemistry, Astrogeology, Astronomy & Telescopes, Biosignatures & Paleobiology, Comets and Asteroids, Icy Worlds, Imaging & Spectroscopy, Interstellar, Press Release

Extreme Negative Polarisation of New Interstellar Comet 3I/ATLAS

by Keith CowingSeptember 9, 2025September 9, 2025

We present the first polarimetric observations of the third discovered interstellar object, 3I/ATLAS (C/2025 N1), obtained pre-perihelion with FORS2/VLT, ALFOSC/NOT, and FoReRo2/RCC, over a phase angle range of 7.7-22.4°.

Combined white light image of 3I/ATLAS, created by median stacking white light images produced by collapsing in wavelength individual data cubes. The field of view displayed is 40" × 40". Intensities are in units of 10−20 erg/s/cm2. -- astro-ph.EP

Astrochemistry, Astrogeology, Astronomy & Telescopes, Comets and Asteroids, Icy Worlds, Imaging & Spectroscopy, Interstellar, Status Report

Initial VLT/MUSE Spectroscopy Of The Interstellar Object 3I/ATLAS

by Keith CowingJuly 8, 2025

The interstellar comet 3I/ATLAS is only the third interstellar object to be discovered. Pre-perihelion measurements provide a unique opportunity to study its activity and composition, which may alter as it […]

The coverage of the Pan-STARRS1 data used in this search, from 2009 April 2 until 2017 November, shown in a Mollweide projection in equatorial coordinates (RA 0 deg is at the center of the plot, with RA increasing to the left). The colors encode, with a linear scale, the number of exposures that cover the region, assuming a circular field of view with a 1.6 deg angular radius, ignoring the ∼ 68% fill factor. The ten Medium Deep fields are shown for completeness. (Note that we skip any data from the Medium Deep fields, as well as from a few exposures for which the processing seems to have failed.) Each has thousands of exposures; we cap the maximum at 600 to keep those fields from dominating the color scale. The median number of exposures is ∼150. A fraction of the sky was not observed at all, and a few regions were observed more than ∼ 400 times. The center of the plot is 0 hr and 0. -- astro-ph.EP

Astronomy & Telescopes, Exoplanets, -moons, -comets, Status Report

A Pan-STARRS Search For Distant Planets: Part 1

by Keith CowingJune 7, 2025June 7, 2025

We present a search for distant planets in Pan-STARRS1. We calibrated our search by injecting an isotropic control population of synthetic detections into Pan-STARRS1 source catalogs, providing a high-fidelity alternative […]

Artistic representation of the distribution of trans-Neptunian objects in the planetesimal disk, with overlaid representative spectra of each compositional group highlighting the dominant molecules on their surfaces. Credit: Graphic art by William D. González Sierra for the Florida Space Institute, University of Central Florida

Astrochemistry, Astrogeology, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Comets and Asteroids, Icy Worlds, Imaging & Spectroscopy, Press Release

JWST Offers The Best Glimpse Yet Into The Icy Planetesimals Of The Early Solar System

by Keith CowingDecember 20, 2024December 20, 2024

New studies led by researchers at the University of Central Florida offer for the first time a clearer picture of how the outer solar system formed and evolved based on […]

Triton, Neptune’s main satellite, passed in front of a star on October 6, 2022. This phenomenon prompted a vast campaign of observations in India, China and from space, led by a scientist from Observatoire de Paris - PSL, to measure the atmospheric pressure prevailing on its surface. Published in the journal Astronomy & Astrophysics on February 27, 2024, the value obtained raises a number of questions.

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Press Release, Triton

Triton Atmospheric Pressure: A New Value Is Obtained

by Keith CowingDecember 19, 2024September 18, 2025

The observation of a stellar occultation by a Solar System object is a very powerful method for measuring its dimensions, as well as possibly detecting rings, revealing an atmosphere and […]