Champaign-Urbana Astronomical Society

02/11/2026

Thursday, February 12 7:00 – 8:30pm.

CUAS monthly meeting - Public invited to attend.

William M. Staerkel Planetarium, 2400 W Bradley Ave, Champaign, IL 61821, USA

A talk will be given by a professional or amateur astronomer on a different topic each month including upcoming astronomical events, constellation lore, CUAS planned special activities, current research, and other topics.

02/10/2026

Daphnis is one of the smallest moons of Saturn, only about 8 kilometers across, yet it has an outsized effect on the planet’s rings. As it orbits within the A ring, Daphnis clears and maintains the Keeler Gap, a channel roughly 42 kilometers wide, through repeated gravitational pulls on nearby ring particles. Each close pass disturbs the particles at the gap’s edges, generating visible waves and ripples that can rise several kilometers above the ring plane. These structures were captured in detail by the Cassini mission and show that Saturn’s rings are not flat or static but dynamic systems constantly reshaped by gravity, even by a moon barely larger than a city.

02/04/2026

https://www.facebook.com/share/p/1DUURAWBrN/

02/03/2026

https://www.facebook.com/share/p/1DXXYfvbsc/

Discover the mind-bending dimensions of Sagittarius A*, the supermassive black hole at our galaxy's center. From event horizon to shadow—it's closer than you think. https://www.freeastroscience.com/2026/01/how-big-is-sagittarius-black-hole.html

01/19/2026

https://www.facebook.com/share/p/1DfBxtt839/

🪐 A distant, icy world with a record-breaking orbit rewrites the story of our Solar System’s edge.

Astronomers have unveiled 2017 OF201, a newly discovered trans-Neptunian object (TNO) likely large enough to be classified as a dwarf planet. Estimated at about 700 kilometers wide, this icy world was detected in data from both the Dark Energy Camera Legacy Survey and the Canada-France-Hawaii Telescope, with 19 sightings between 2011 and 2018.

What truly sets 2017 OF201 apart is its astonishing orbit. It journeys from a perihelion of 44.5 astronomical units (AU)—close to Pluto’s distance from the Sun—all the way out to a staggering 1,600 AU, deep into the inner Oort Cloud. Completing this immense path takes around 25,000 years, making it one of the most extreme orbits ever recorded for any known solar system body.

The discovery was possible thanks to deep-sky surveys and careful tracking, allowing the scientific team led by Sihao Cheng to precisely chart its distance, size, and highly eccentric course. Simulations indicate that such an orbit could not remain stable if the hypothetical Planet Nine existed; that planet’s gravity would have long since ejected 2017 OF201, suggesting the absence—or at least a different nature—of Planet Nine than previously theorized.

2017 OF201 hints at a vast, hidden population of similar objects beyond Neptune—worlds waiting to be found. Its existence challenges assumptions about the Solar System’s structure and beckons astronomers to keep searching the distant frontier.

📄 RESEARCH PAPER

📌 Sihao Cheng et al., “Discovery of a dwarf planet candidate in an extremely wide orbit: 2017 OF201”, arXiv (2025)

01/18/2026

https://www.facebook.com/share/p/17R3udm1eT/

Before this day, the universe was thought to be still.

On January 17, 1929, American astronomer Edwin Hubble published a paper that would transform modern cosmology. Using observations made at the Mount Wilson Observatory, Hubble presented clear evidence that the universe is expanding—a radical idea at the time.

Hubble compared the distances of galaxies (estimated using Cepheid variable stars) with their redshifts, which indicated how fast they were moving away from Earth. The result was a striking linear relationship: the farther away a galaxy is, the faster it's receding. This became known as Hubble’s Law, and it provided the first observational proof that space itself is stretching.

Until then, many scientists had believed the universe was static and eternal. Hubble’s discovery, however, supported theoretical predictions made by Alexander Friedmann and Georges Lemaître, who had used Einstein’s equations to show that a dynamic universe was possible.

This insight became the foundation for the Big Bang theory, reshaping our understanding of cosmic origins and evolution.

01/08/2026

Zoom in on some of our favorite astronomical objects with James Webb Space Telescope

On the launch anniversary of the NASA/ESA/CSA James Webb Space Telescope, ESA presents a unique compilation of zooms into stunning cosmic views.So embark on ...

01/08/2026

LSST
This lets you zoom in to the first images from LSST ----
https://skyviewer.app/explorer?target=187.77035+8.07268&fov=5.00

01/08/2026

This is a new era in Astronomy
The Dr. Vera Rubin Observatory in now operational and has the largest camera in the world. The Legacy Survey of Space Telescope (LSST) camera is the size of a small car with a 5-foot diameter front lens and 28 foot primary mirror. Its’ 3-gigapixel sensor is 225 times more than my Nikon DLSR. The FOV = 10 square degrees =45 full moons
It takes 1,000 of 30 second exposures every night = 20 Terabytes every night for 10 years. That’s 500 pentabytes of processed calibrated data. = 5 with 17 zeros. Just try and wrap your mind around that! It will find 10 million transient events each night. It will photograph the entire southern sky every 3 to 4 days. The data will be sent to Urbana via dedicated fiber optic cable all the way from Chile.
o It will Catalogue asteroids, especially potentially hazardous ones.
o It will map the large-scale structures of the universe to understand Dark Matter & Dark Energy: In college, we called it the “Missing Mass”
o It will discover transient events like supernovae and variable stars.
o It will map the structure, formation, and faint stellar populations of our galaxy.
In 1970s Dr. Rubin discovered “dark" matter in the Universe. She found that the stars at the outer edges of galaxies were moving just as fast as those towards the center and that was against the laws of physics.

The Large Synoptic Survey Telescope (LSST) is a wide-field reflecting telescope that will digitally scan the entire available sky every few nights from its m...

01/06/2026

Reminder: The January meeting of the Champaign Urbana Astronomical Society (CUAS) will be held this coming Thursday, 01/08/2026 beginning at 7:00pm at Staerkel Planetarium.

01/05/2026

https://www.facebook.com/share/p/17zxkdKDBX/

On this date, Jan. 3, in 1888, the refracting telescope at the Lick Observatory, measuring 36 inches (91 cm) in diameter, was used for the first time. It was the largest refracting telescope in the world until 1897 and now ranks third, after the 40-inch instrument at the Yerkes Observatory and the Swedish 1-m Solar Telescope.