If you have never heard of the Herschels, then you are missing out on the most important astronomers of the 18 th and 19 th Century. William Herschel, discoverer of Uranus,
together with his able and dedicated sister Caroline and his erudite son John revealed the Milky Way and its diverse contents as never before.
This year, our eyes were once again redirected to our own Solar System for a just a few fleeting
minutes -- from the myriad wonders of our “seeable” Universe to a small space probe called New
Horizons that at 7:49 AM (EST) on July 14 th 2015 passed within 7,750 miles of little Pluto at a
record-breaking speed of 30,800 miles per hour (49,600 kilometers per hour).
We’ve all shown Saturn to someone, or perhaps have shared a clear view of a bright globular, say, M13, with someone who hasn’t seen such a thing before. In these and similar cases, the sheer beauty of the thing is the whole point; any impressive facts are secondary.
“It does not do harm to the mystery to know a little about it. For far more marvelous is the truth than any artists of the past imagined it. Why do the poets of the present not speak of it?” -- Richard Feynman (1918 – 1988)
Each year, the American Astronomical Society (AAS) hosts two big meetings in January and June that span all of astronomy and its subfields of cosmology, helioastronomy, and planetary science. The COVID-19 pandemic took its toll, beginning in June 2020, when the meeting format pivoted to online presentations. The January 2022 meeting was canceled outright, but by June 2022, the society pivoted again, offering a hybrid mix of in-person and online formats. These two meetings underscored the unquenchable thirst for astronomical questing among our veteran and rising scientists. Here are a few highlights from these meetings.
The formula for collisional excitation of the atoms responsible for auroral emission can explain why green auroras from excited oxygen atoms can occur at relatively low altitudes, but red auroras from these same atoms are constrained to higher altitudes of lower density. The same formula also suggests much lower electron velocities (~100 km/s) than are required to excite the oxygen atoms to the required metastable levels for subsequent emission (~1000 km/s).
Fast Radio Bursts are flashes of radio emission lasting for several milliseconds. The time of arrival of signals depends on the radio frequency, called the dispersion measure (DM), which depends on the environment through which the signals travel, specifically the number of free electrons in their path. Very few FRBs have matches with sources observed at other wavelengths (Wikipedia - Fast Radio Burst).
Galaxies comprise the largest self-gravitating systems of luminous matter in the universe, swirling masses of matter and energy just looking for trouble. Over the past few decades, astronomers have come to appreciate how fervently active galaxies can be. Besides hosting roiling clouds of intense starburst activity, they often also sport supermassive black holes in their centers that can pack a powerful punch. These myriad histrionics can affect the host galaxy's subsequent evolution and even the destinies of neighboring galaxies.