ASTRONOMY
In the Sky this Week, Astronomy News, and TWSftUoTtCBDftSoTiFoOT
ASTRONOMY NEWS
Perhaps a Great Comet! Be on the lookout for comet C/2024 G3 ATLAS, very low in the western twilight sky! It reached perihelion on Monday (1/13), and could possibly become brighter than comet C/2023 A3 Tsuchinshan-ATLAS was!
“Planet 9” Revisited: Observations of “Extreme Trans-Neptunian Objects” and the determination of their orbit parameters perhaps point to the influence of another, as yet undiscovered, dwarf planet in the outer Solar System, in addition to the “seven dwarfs” in the Item of the Week. Enthusiasts wanting to return to the day of a planetary Pluto call it “Planet 9,” but there is no doubt the IAU would disagree. Computer modeling suggests the hypothesized body would be 5-10 x Earth’s mass and orbit the Sun at a distance of on the order of 550 AU. The idea of a larger ETNO has been around for some time, and something may be needed to explain the observed alignment of the perihelia of some ETNOs.For a summary of this work, see: https://www.astronomy.com/science/does-planet-nine-exist; for the paper in Astronomy and Astrophysics, see: https://www.aanda.org/articles/aa/full_html/2024/12/aa50124-24/aa50124-24.html
ASTRONOMY FYI
Polynesian Navigation: The two Moana Disney movies have sparked interest in the skill of the Polynesian navigators. The Phys.org website posted a piece on Christmas day about it; see: https://phys.org/news/2024-12-disney-moana-characters-stars-astronomer.html. Polynesian traditional navigation was also the topic of a previous A+StW Item of the Week, see: https://www.airandspacethisweek.com/assets/pdfs/20200525%20TheStarofGladness.pdf.
Parker Solar Probe at 0.04 AU (!): The PSP made its closest approach ever to the Sun last week, passing a mere 3.8 million miles from the “top” of the Sun’s photosphere while it endured the 2,500 °F temperatures there. Talk about fireworks to celebrate the Heliophysics Big Year with yet another success for the PSP! Data is has acquired have allowed a better understanding of the high degree (sorry) of heating in the solar corona and the nature and acceleration of the solar wind. For more on this latest success: https://phys.org/news/2024-12-nasa-parker-solar-probe-survives.html.
IN THE SKY THIS WEEK
Sun: The Sun has an ~11-year cycle of sunspot activity. The last minimum period was in late 2020; the next maximum has just now been reached. Peak conditions could persist for the next year, so expect more sunspots, CMEs, and auroral displays in the coming months! NOAA’s 30-Minute Aurora Forecast: https://www.swpc.noaa.gov/products/aurora-30-minute-forecast.
Nova Watch: No, I’m not promoting the really good PBS series, I’m talking about T Coronae Borealis, a recurring nova. It’s usually about magnitude +10, not exactly a target for most backyard astronomers. However, every 80 years or so, it goes nova, becoming as bright as Alphecca, the brightest star in the Northern Crown (Corona Borealis). The last time it blew was in 1946, and its starting to show the same signs it did back then before it brightened.
I would suggest you become familiar with the look of this particular constellation so you can see the change for yourself when it happens. You can find out more about it at: https://skyandtelescope.org/astronomy-news/observing-news/this-weeks-sky-at-a-glance-june-7-16 . There is a link within to a 2016 Sky & Telescope article by Bob King that shows you how to find T CrB at its normal brightness. There’s even a more recent S&T piece that will help you find the “Blaze Star”: https://skyandtelescope.org/astronomy-news/is-the-blaze-star-about-to-blow-you-may-be-the-first-to-know. We’ll need a little luck, since the maximum brightness of T CrB will only last a few hours.
Here's the Latest on T CrB: https://phys.org/news/2024-09-flares-blaze-star-corona-borealis.html!
A Helpful Tip from Dr. Steve: If you do an Internet search on “Blaze Star,” be sure you don’t channel your inner Ringo and spell it with two “r”s. Just ask Governor Earl Long….
Moon: Full Moon (“Wolf Moon”) occurs at 5:27 PM EST on Monday, January 13. At almost exactly that same time, the Moon will occult Mars! For more info on that event, see: https://www.astroleague.org/wp-content/uploads/2024/11/2025-Jan-13-Moon-occults-Mars.pdf.
Mercury has now moved into the morning sky. You’ll need a clean horizon and clear sky. Look to the southeast 45 minutes before local sunrise; it’s there, shining at -0.3.
Venus (-4.6) absolutely dominates the southwestern evening twilight sky, in Aquarius. In the telescope, has just barely gone by “Dichotomy,” (~50% illuminated).
Mars (-1.4) rises in the late evening. It lies below Castor and Pollux, near the Cancer/Gemini border. It’s nearing the eastern stationary point as it starts its retrograde loop prior to Opposition (on 1/15/2025).
Jupiter (-2.6) rises just after sunset this week, since it reached Opposition on December 7. As the weeks go on, it will dominate the eastern sky the same way Venus is dominating the western sky now. This is a good time to look at Jupiter with a telescope; it’s still 46 arc-seconds across!
Saturn is presently in Aquarius, to the lower-right of the Great Square, shining at +1.1. In the coming weeks, it will pass closely by Venus, with the two being only 2.2° apart on 1/18/2025.
Uranus lies in western Taurus near the Pleiades, shining at +5.6.
Neptune (+7.8) is in Pisces, doable but you’ll need a sky chart.
COMETS
Comets (presently brighter than +10): There are presently only one. Barely. That will, I hope, change in a few days…
Comet Watch: The Asteroid Terrestrial-Impact Last Alert System (ATLAS) has detected another Sun-grazing comet coming in, C/2024 G3 ATLAS. It’s presently shining at -2, just west of Capricornus. Its lateral motion is quite high as it approaches perihelion on January 13. It’s looking like it is still holding together. If it survives perihelion passage, unlikely because it will be only 0.09 AU from the Sun, it will be quite bright (-4!).
No other comets are anywhere near +10.
For info on comets currently visible, see: http://www.aerith.net/comet/weekly/current.html.
SATELLITES NEXT WEEK
International Space Station
There are three overpasses of the ISS this week for those of you in the DC area. Not one of them is worth looking for; the best culminates at only 32°.
There are only three overpasses of the ISS during the next week for those of you in the Colorado Springs area. None of them culminate higher than 30°.
Hubble Space Telescope
There are ten visible overpasses of the HST this week for those of you in the DC area. To see the three most favorable, look 17° above the S horizon at: 6:45 PM EST on 1/20; 6:21 PM EST on 1/21; and 5:57 PM EST on 1/22.
There are seven visible overpasses of the HST this week for those of you in Colorado Springs. For the best three of them, look 16° above the S horizon at: 6:19 PM MST on 1/20; 5:55 PM MST on 1/21; and 7:11 PM MST on 1/22.
To find out about satellite overpasses in your area, see https://heavens-above.com (set your own location in the upper-right corner).
Continue the Heliophysics Big Year Celebration! NASA’s Science Mission Directorate comprises four divisions: Astrophysics, Heliophysics, Planetary Science, and Earth Science. From time to time, a division will institute a year or so long outreach effort. When I was at HQ, the emphasis was on the “Year of the Solar System.” Now, we are in the middle of an 18-month “Heliophysics Big Year.” The 2024 total Solar eclipse was one of the big events of the Big Year, and the ongoing data from the Parker Solar Probe, the Solar Dynamics Observatory, and other assets make for good engagement material. Free Heliophysics and Math Webinars are available, too; find out more at: https://science.nasa.gov/learning-resources/science-activation/celebrate-the-heliophysics-big-year-with-free-heliophysics-and-math-webinars-from-nasa-heat. And, of course, check out the recent Item of the Week about the Solar and Heliospheric Observatory! [Didja know that there are 27 spacecraft in 20 missions in Space right now observing the Sun? Not all of them are NASA’s, but that’s still a lot!]
Dark Energy Might Not Even Exist! A team of scientists at New Zealand’s University of Canterbury have published a model of the early Universe in which expansion is not uniform. “The new evidence supports the "timescape" model of cosmic expansion, which doesn't have a need for dark energy because the differences in stretching light aren't the result of an accelerating universe but instead a consequence of how we calibrate time and distance.” For more info, see the article from which the quote came, at: https://phys.org/news/2024-12-dark-energy-doesnt-lumpy-universe.html.
Without Infrastructure, Little is Possible: A truism in many contexts, including astronomy. For example, images from the James Webb Space Telescope dazzle professional astronomers and the public alike. The really-complex-yet-extremely-successful satellite is a marvel of engineering design and construction (as only NASA can!). But JWST would be of no value without the supporting infrastructure here on Earth that receives the information from its instruments.
Downlinks of data are always of paramount importance, but communicating with satellites in LEO or Geosynchronous orbit is simple compared with receiving data from JWST, which orbits the Sun-Earth L2 point, a million miles away. NASA’s Deep Space Network, originally built 60 years ago to ensure continuous radio contact with early manned spacecraft, is still up to the task! Although I’d bet that the electronics of their receivers and transmitters may have had an upgrade or two over the decades!
The DSN is an engineering marvel. For a summary, see here; for the DSN website, see here; and if you want to see whose signal the DSN is receiving, see here.
TWSftUoTtCBDftSoTiFoOT
The World Society for the Understanding of Things that Can Be Understood from the Study of Things in Front of Other Things says: An astonishing amount of Science can be conducted via the Study of Things in Front of Other Things! Examples range from the confirmation of Relativity by observations made during a total solar eclipse to asteroid shapes to rings around Uranus to planets of other Suns. Since many exoplanets have been discovered when they were “in front of other things,” all exoplanet and SETI news and info will be covered in the section below.
A Primer in Transits: NASA posted an introductory piece to the TWSFTUOTTCBDFTSOTIFOOT favorite of planetary transits here. Detecting the small drop in light from a star when its exoplanet transits across its face is one of the primary means of detecting exoplanets, enabled by ground-based observation and satellites like Kepler and TESS. While the transit method has produced many exoplanet findings, but other methods are useful, too (see immediately below).
Interesting Exoplanet: LHS 1140 is a red dwarf star located 48 light-years from Earth in the constellation Cetus. It has a “super-Earth” exoplanet orbiting in its “Goldilocks Zone” and a bulk density that suggests that ~10% of its mass is water. It’s been known for some time, but only recently have the system’s physical properties been determined accurately. Its rotation is tidally-locked with its year, meaning that it always keeps the same face pointing sun-ward; estimates of temperatures there are a balmy 70°F! For a summary of our study of this interesting place, see here: https://earthsky.org/space/ocean-world-lhs-1140-b-exoplanets-astrobiology; for a paper about it in The Astrophysical Research Letters, see: https://iopscience.iop.org/article/10.3847/2041-8213/ad5afa!
Confirmed Exoplanets: Now 5,502! Over 31 years ago, the first two confirmations of planets orbiting another star were made. It was a strange system, since they were both orbiting a pulsar! Now, the announcement of six new confirmations has pushed the total of definite exoplanets to 5,502. For of the new finds were made by the transit method, one by the radial velocity method, and one was made by direct observation.
SEARCH FOR HABITABLE EXOPLANETS
Habitable Worlds Observatory: Yes, Virginia, there will be such a thing in the future. The 2020 Astronomy Decadal Survey strongly recommended that NASA “develop a 6-meter Space telescope capable of high-contrast observations in optical, infra-red, and ultraviolet wavelengths.” Its primary mission will be to examine 25 different exoplanets in detail, all in their star’s “Goldilocks Zone,” searching for biosignatures. Knowing which stars to choose is obviously of great importance. That work is presently underway; NASA’s Exoplanet Exploration Program has developed a list of 164 candidates to date, based on five selection criteria: stellar composition, photometric values, flare rate, variability, and potentially-sterilizing X-ray emissions. For more information on this project, see: https://phys.org/news/2024-01-astronomers-habitable-worlds-observatory.html and https://science.nasa.gov/astrophysics/programs/habitable-worlds-observatory.
SEARCH FOR INTELLIGENT LIFE ELSEWHERE
Part 1: UCLA’s Jean-Luc Margot is the founder of UCLA SETI’s “Are We Alone in the Universe?” project. Their mission is to detect “technosignatures by searching individual systems. Dr. Margot teaches a graduate course in SETI, and he had his students use TESS data for the closer known exoplanets to narrow the search for such emissions in great detail. No provable technosignatures were seen. Even though the smally sample observed didn’t show emissions, the skills developed by the students (e.g. signal processing, telecommunications, and statistics and other data analysis tools) will no doubt improve their academic success.
Part 2: Traditional SETI tactics, like Dr. Margot’s project, is one way to search. The Breakthrough Listen program (which uses citizen scientists) takes a different approach. Rather than look at relatively-close systems, they are using the Green Bank (West Virginia) and Parkes Murriyang radio telescopes to look for very high powered technosignatures, an entire galaxy at a time. For more on this program and strategy, see: https://phys.org/news/2023-12-breakthrough-scans-entire-galaxies-extremely.html.
Part 3: NASA has produced a six-part on-line series on how it is searching for life in the cosmos. If you are interested in the real science behind this topic, then check out these episodes! Part 1: Beginnings: Life on Our World and Others; Part 2: Life on Other Planets: What is Life and What Does It Need?; Part 3: The Hunt for Life on Mars – and Elsewhere in the Solar System; Part 4: “Life” in the Lab; Part 5: Searching for Signs of Intelligent Life: Technosignatures (see also this week’s Gravity Assist entry in the Solar System section); and Part 6: Finding Life Beyond Earth: What Comes Next?
What Happens After We Discover Life Elsewhere? Mary Voytek, Director of NASA’s Astrobiology Program, has some interesting thoughts on the subject. Check them out at: https://exoplanets.nasa.gov/news/1766/finding-life-beyond-earth-what-comes-next!
Exoplanet Travel Bureau is NASA’s source for whimsical travel posters showcasing various exoplanets as tourist destinations and other exoplanet information. See: https://exoplanets.nasa.gov/alien-worlds/exoplanet-travel-bureau!
ASTRONOMY LINKS AND OTHER INFORMATION
Astronomy.com: https://astronomy.com/news
Phys.org: https://phys.org/space-news/astronomy
Space.com: https://www.space.com/news
Science Daily: https://www.sciencedaily.com/news/space_time/astronomy
Sky and Telescope: https://skyandtelescope.org/astronomy-news
NASA Exoplanet Exploration News: https://exoplanets.nasa.gov/news