TGT #25D - NEO Resources - Planets Come and Go - The Moon's Tilted Orbit - A Total Lunar Eclipse to View and Teach With
TGT 3/1/25: TJI--What's the Deal with 2024 YR4's Crashing to Earth?; SPC--Mercury Almost Meets Venus Before BothVanish, Jupiter Helps Show Moon's Orbital Tilt; TCA--3/14 Lunar Eclipse; AEL--Physics!
Cover Photo - The Almost City-Killer
In This Issue:
Cover Photo — The Almost City Killer
Welcome to Issue #25D!
This Just In —
* The Almost City Killer, 2024 YR4 and Why Chances Keep Changing
* NEO ResourcesSky Planning Calendar —
* Moon-Gazing - Use the Moon and Jupiter To View Moon’s Orbital Tilt
* Observing—Plan-et - Venus and Mercury Almost Meet But Go Away Together
TCA — Astronomical Teachniques with the 3/14 Total Lunar Eclipse
Astronomy in Everyday Life — Physics Terms in AEL
Welcome to The Galactic Times Newsletter-Inbox Magazine #25D!
Greetings, Galactic Timers!
We’re in orbit over this Issue! In This Just In, as well as in many mainstream media, is the story of the small asteroid discovered just before New Year’s. 2024 YR4 has had a varying amount of probability to hit the Earth in the very near future. As high as above 2%, down to zero. How did that happen? What sources are there to monitor yourself the news on Near-Earth Objects (NEOs)? You’ll find both those timely articles here.
Then while just observing the sky, especially the Moon, you can watch the Moon’s path among the stars until it gets nearest to Jupiter, illustrating that the Moon not only is NOT following the Ecliptic line but shows visible evidence of the tilt of its orbit around Earth. See Moongazing in the Sky Planning Calendar.
Regarding that orbital tilting….the Moon goes from North to South of the Ecliptic right at Full Moon, thereby having a Total Lunar Eclipse. A bit of an inconvenient hours-long event for some, it still has some educational value. In TCA-Towards Cosmic Awareness, we illustrate two kinds of educational activities—astronomical teachniques—one based on a poster report at January’s AAS meeting adapted from total eclipses to lunar eclipses, and one we’ve published before on using the Moon to get its distance and diameter.
This once Astronomy in Everyday Life should temporarily be rechristened Physics ….. for we show the some physics words found in the public eye.
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Publisher — Dr. Larry Krumenaker Email: newsletter@thegalactictimes.com
This Just In
The Almost City Killer, 2024 YR4 and Why Chances Keep Changing
There has been much in the news recently about a small asteroid discovered that appears to have a slight chance of hitting our planet within just a few years. The chance was as “much” as about 3% but has since dropped back to essentially zero. Why the variation?
Go outside into an area that is large and clear of most buildings and trees, no mountains or hills would be good but even along a lot of interstates with few dips or inclines will do.
Now look as far as you can across this virtually flat zone. Almost looks infinite, fading in the distance with hopefully clear blue sky above it, right? How far away is that infinity? Usually about three miles. Why is that? Because it is only after that amount does the curvature of the Earth matter enough to put the visible ground “under’ the ground and hidden from view. The Earth looks flat (or, here, straight). You have to go some considerable distance (for a 5 or 6-foot sized human) to start seeing the effect of Earth’s curved surface deviating from flatness. A thing that flummoxed people in ancient times. And flat earthers today.
The same thing happens with the orbits of newly discovered objects in the solar system. First, we generally only observe motions that are going across the sky; things moving AT us directly don’t appear to move. Other things will show that motion—increases in size, brightness, radial velocity in spectra. That’s harder to spot. Second, we know that all orbits are elliptical around the Sun (or moons around a planet but that’s another story). Though those curved pathways eventually reveal themselves, over short time frames for observations they often appear essentially….straight (i.e. like flat Earth surfaces). The determination of orbits requires at least three, preferably more, and as widely spaced in time as possible observations in order to get that curvature noticed and calculated in order to predict its future locations. Thus an asteroid or comet or, here, Near-Earth Object on a collision course with Earth may be seen to be aimed right at us, on a straight bee-line. Until enough observations are made to see that ellipticality finally evident.
2024 YR4 took a bit of time before that elliptical orbit was evident enough to say it will miss us. But when they are that near to us, it is a short term, need observations fast (and highly precise) to see if a warning is needed, or a DART-like mission to launch.
NEO Resources
The discussion on the planetarium community on portraying this encounter-possible was rather dynamic. Several websites to keep an eye on possible colliders were presented, especially from astronomer Rob Landis:
A JPL video on how the increasing accuracy occurs from multiple observations and the Monte Carlo statistical analysis method can be found on Youtube, in English at https://www.youtube.com/watch?v=UWhj4qJdYWw and in Spanish at https://www.youtube.com/watch?v=LAFmHmwuKyA . [I am leaving these unlinked because Substack tends to go and put up the first, very large image of the link video. Cut and paste into your browser URL box.]
IAWN, the International Asteroid Warning Network, can be monitored at https://iawn.net/index.shtml .
Information on this tiny rock can be accessed on IAWN at https://iawn.net/obscamp/2024YR4/index/shtml .
Other NEO observations are reported on https://neo.ssa.esa.int/-/latest-cafs .
Sky Planning Calendar
Moon-Gazing
Moon passages by a star, planet or deep sky object are a good way to find a planet or other object if you’ve never located it before.
March 1 A busy day, or night.
First, the Moon is at Perigee, its nearest time to Earth and largest in apparent size. A Super Crescent Moon, if you like. It is also at ascending node, just before midnight (i.e. February 28th) or just after, depending on your time zone.
Second, 6-degrees to its South (to its upper right) is low but still brilliant Venus.
Lastly, for those in Australia and Polynesia it will pass over Mercury, otherwise it passes by at only 0.4-degrees or less. Mercury otherwise below left of Venus.
March 5 In the dawn you’ll find the Moon its own diameter, 0.5-degrees, from the star cluster the Pleiades.
March 6 Jupiter is an unimpressive 6-degrees South of the Moon. What’s more interesting and educational is that the First Quarter Moon is at its highest distance above the (invisible) Ecliptic, the sky reflection of Earth’s orbital plane. This is as high in the sky as it can possibly get, in terms of distance above Earth’s Equator, so take a good look, realizing that Jupiter is 0.4-degrees south of the Ecliptic. This also gives you a good idea and measurement of the tilt of the Moon’s orbit compared to Earth’s, a roughly 6 degrees. This is why we don’t have eclipses every month; the Moon usually passes above or below the Ecliptic on New and Full Moons by more than the Moon’s diameter of one-half degree, hence it neither casts its shadow on Earth or passes through Earth’s, though this month it does do both. Sort of….
Oh, and as a bonus, if you are in southwestern USA or Mexico, the Moon’s edge grazes Beta Tauri, the lower horn tip of Taurus the Bull (and pointer to the telescopic wonder the Crab Nebula).
Beta, by the way, got its name from the stellar mapmaker Johann Bayer. Watch this passage of the Moon by the star, whether it grazes in your location or not, and celebrate the eve of the 400th anniversary of the death of Bayer, the man who gave it its name.
March 8 Mars lies 1.7-degrees away from the Moon. Best to look for it one hour after Sunset.
March 9 The Gemini Twins star Pollux lies about 2-degrees from the enlarging Moon. Pollux rhymes with bollixed which is what you will be this morning when Daylight Savings Time begins!
March 13-14 Full Moon and a Total Lunar Eclipse. See below.
March 16 Spica is less than a lunar diameter from the Moon.
Observing---Plan-et
==Last Evenings with Venus and Saturn; Hello, Mercury==
Mercury can be found using Venus as a guide. Venus is tumbling downwards into the solar glare, gone by month’s end, while Mercury is starting a good evening apparition, moving upwards away from the Sun, reaching its maximum distance from the Sun in our view of 18-degrees on the 8th. Mercury never quite gets further from the Sun in Earth’s skies than Venus in this apparition but it is observable as nearly horizontal and to the left of Venus around the 12th, after which the two worlds go hide in the solar glare with a conjunction two days apart before month’s end.
Mercury does one other interesting thing to note. It will actually set (barely) in darkness from the 5th to the 10th, setting after evening twilight has ended.
Venus, as noted above, starts out brilliant at month’s start and it sets at or before evening twilight ends from the 10th onwards. It also does an interesting thing. As it approaches conjunction with the Sun, nominally invisible, it actually passes around 9-degrees above the Sun. Under the right conditions you can see Venus setting in the evening twilight and rising in the morning twilight during the same night! In fact, it will be technically visible under these conditions from the 15th in the dawn through setting in the evening twilight until the 22nd. A week for a double dose of Venus!
A telescope or even binoculars can show Venus’ exquisite crescent shape, nearly 1’ (one minute of arc) in size (most people can resolve things in the sky at about 2’) and a mere 4% wide and shrinking at midmonth.
Mars fades rapidly now, to below negative magnitudes, becoming a bright red star but little different from such red giants as nearby Aldebaran. Find it near the Moon on the 8th.
Jupiter rules the evening sky, and sets not much after midnight, but gains an hour more because of Daylight Savings Time!
You might get a glimpse of Saturn around the 1st but it reaches solar conjunction on the 9th. Its rings would be barely telescopically visible, not just because of the bright twilight sky but also because in two weeks the Earth passes through the plane of the rings.
TCA-Astronomical Teachniques, featuring the Total Lunar Eclipse of March 13-14
With the Moon near Apogee, its small bright disk would fit inside the northern part of Earth’s umbral, central shadow, well, it does but just barely. During this eclipse it will be dark on its south edge, perhaps even reddish, but nearly unshadowed bright on the northern edge. The popular press always calls total lunar eclipses Blood Moons but this one is likely more like a Mars with a polar ice cap.
The eclipse, for North and most South Americans, can be seen in full but at an inconvenient hour during the work week. Using Eastern Daylight Time as our standard, you can adjust the times below according to your time zones to the West.
The dusky penumbral outer shadow begins to cover the Moon’s surface at just three minutes to midnight on the 13th, but you won’t see it—too thin—until maybe 20 minutes before partial phases begin, at 1:09 AM EDT on the 14th.
This umbral partial phase will last more than an hour, until totality begins at 2:26 AM, although that northern edge of the Moon may hardly look it.
Totality is just a bit more than an hour, too, ending at 3:32 AM. Then the pattern reverses. An hour and 16 minutes later, the partial phases end, at 4:48, just before twilight begins. You might still get a glimpse of the waning penumbra for another 20 minutes, max.
Australia, extreme eastern Asia, most of Europe and Africa will see at least part of this eclipse.
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Gerard Williger and Jennifer Birriel, of the University of Louisville and Morehead State University respectively, had a poster presentation at the January American Astronomical Society meeting that has some relevance here. Their report was on a one-credit course on solar eclipses. It covered sky motions, solar and lunar eclipses, Sun-Earth-Moon system, science done during solar eclipses, how to observe them, historical eclipses, and the relationship to exoplanet observations. They had 16 questions students had to investigate. Some of their questions, those meant for solar eclipses, that might make for educational use in total lunar eclipses, like the one this month. With modifications.
How dark is the Moon/sky during totality versus partial phases? Here you might measure the latter by seeing how faint a star you can see. You might measure the former using a light meter.
What fraction of Earth sees totality, and is it at different times for all observers or the same moment?
What is the average time between total eclipses seen in one location? Perhaps use timeandspace.com to get your data.
Do solar eclipse glasses help or hinder the view?
Can you see totality from the city or just the countryside?
What scientific results can come from a total lunar eclipse? This requires scientific journal searches on the professional end while measuring the passage through the shadow can measure the Moon’s diameter and distance using techniques known even to ancient Greeks; both the 2009-2015 The Classroom Astronomer magazine and the now dormant newsletter of the same name have published stories on how to do that. You can find the magazine’s three-part article on the resources part of the website https://www.classroomastronomer.com/measurethemoon .
For the Future
A partial SOLAR Eclipse will be visible in the latter half of March in NE USA, Eastern Canada, and parts of Europe. More on that in the next issue of The Galactic Times.
Astronomy in Everyday Life
Physics Terms in AEL….
Spotted every recently on the road, you’d need a lot of that to gravitationally or explosively change the path of a NEO…..
Lumen, the unit of measurement for the amount of light, is the name of this hotel and restaurant in Birmingham, AL. It is getting plenty of those from the street lamp next to it…..
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