TGT #26 - Observing--Does Mercury Look Reddish to You?; + 9 more [June 16, 2022]
This Just In--A Multiplanet Discovery Nearby, Cold Cosmic Clouds Covered Earth 2 My Ago, What Makes a Red Star "Wonderful"? and What Turned On the Universe' Lights?; Moon Points to Planets and Mira.
On the morning of June 27th, compare Mercury, to the right of the Moon, with red giant star Aldebaran. That’s the bright star that a line from the Moon through Mercury almost points to. But the star also lies below Venus, so the two lines make a roughly 90-degree angle at Aldebaran. Are Mercury and Aldebaran the same color? Brightness?...
In This Issue:
Cover Photo — Mercury, Venus, Moon, and Aldebaran
Welcome to Issue 26!
This Just In — * Hiding in Plain Sight! * It was Cosmically Cloudy and Cold About 2 Million Years Ago… * The More Metal, the More Wonderful? * What Turned On the Universe’s Lights?
Sky Planning Calendar — * Moon-Gazing - Moon Glides the Grand Line-Up Planets - Moon Stands in for Earth, and Points to Mira * Observing—Plan-et — - Does Mercury Look Reddish to You? (Cover Story) - The Solstice - Cetus and Other Zodiac Constellations, and Jupiter
* Border Crossings
The Classroom Astronomer Newsletter-Inbox Magazine #28 June 12, 2022 Issue Highlights.
Welcome to The Galactic Times Newsletter-Inbox Magazine #26 !
I’m (virtually) at the American Astronomical Society 240th meeting, writing between sessions, and this is just the first of three consecutive weeks of meetings!
Or I was ‘there’ but now I’m not and I have got far more stories than this issue has room for! Or time to write them since my participation ended yesterday and this is to go out today, the 16th. So I am going to write up the interesting smaller stories and save the big ones (and there are some BIG ones with juicy details) for the next issue(s).
Additionally, the sky is getting interesting, assuming the summer heat, humidity, and storms allow you to view it. We’re in peak Grand Line-Up time, when the planets from Mercury to Saturn are in the dawn in natural order from the Sun. Note they are not in equal spacing, nor on the Ecliptic itself, nor even directly all in an exact straight line, NOR not even all in traditional zodiac constellations (am I picky or what?). In fact, as pointed out elsewhere, there are more than the standard 12 zodiacal constellations. Try using that to win a beer bet! And the Moon not only stands in for Earth for three days but if you follow it daily it will introduce you to all the planets individually, if you’ve never seen them before, especially little Mercury. In fact, Mercury lies near reddish Aldebaran and since some claim Mercury can appear red, this is a good time to check out that hypothesis. The Moon also gives you an early pointer to star that really is red, Mira, The Wonderful, in Cetus the Whale, the focus of another story in this issue.
Happy Solstice everyone. We have summer product plans. Stay tuned…
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First, three news stories from the American Astronomical Society (AAS) 240th meeting in Pasadena….
* Hiding in Plain Sight!
In one of the most crowd-pleasing and creative presentations at the AAS meeting, University of Chicago astronomer Dr. Rafael Luque announced the discovery of two rocky, slightly-bigger-than-Earth planets around a star not far from the Sun in a highly entertaining style fit for a Hollywood celebrity story.
Casting the two planets, b and c, around star HD 260655 as celebrities hiding in plain sight and found by ‘paparazzi’, the telescopes HiRES and CARMENES as they transited in front of the star, they had to be outed, uh, confirmed by the “Big Brother” TESS satellite with more precise transits. Given their periods around the star, and their sizes as determined by their transits, their masses turn out to give densities of 4.7 and 6 grams per cubic centimeter (Earth is about 5.5) that could only be that of rocky worlds, not gas giants like many exoplanets found these days. Their diameters are only 2 and 3 times Earth’s. Earth gravity’s g is 9.8 m/sec-squared; these guys are both about 13 in the same units—you’d struggle a bit and fall down easily. They orbit close to the M0 dwarf star, with orbital periods just under 3 and 6 days. The star may be cool but it’s hot there…..
So what?
This makes HD 260655 b and c the fourth closest multi-planet star system to the Sun, only 32 light years away. It is the closest single-star M dwarf multi-planet system. And it puts these nearby worlds in the top 10 V.I.T (as the astronomer puts it, Very Important Targets) for the James Webb Space Telescope.
Don’t try to emulate the paparazzi…..the star is magnitude 9.77, at coordinates RA 6:37, Dec. +17d 34', in Gemini, far too close to the Sun right now to see or photograph.
* It was Cosmically Cloudy and Cold About 2 Million Years Ago…
Space is not empty. There are multitudes of thin dust clouds through out the galaxy, and they are very cold. They are not thick enough to be visible but enough to cause climate change. How? Because the heliopause, that boundary between the Sun’s magnetic protection for the Solar System and the rest of the Universe, isn’t strong enough to keep dust out. When the Sun travels through a dust cloud, whether because we move into it or it moves onto us, the heliopause can collapse under the pressure.
A simulation of cold dust clouds in the solar system’s galactic neighborhood.
Astronomers Merav Opher and Abraham Loeb, of Boston University, Boston, MA, Harvard University, Cambridge, MA, respectively, found there is “geological evidence from Fe and Pu isotopes that Earth was in direct contact with the interstellar medium (ISM) 2-3 million years ago, and the local ISM is home to several nearby cold clouds.” This limits the amount of galactic cosmic rays that affect Earth. They propose that the heliopause, and with it, the heliosphere enclosing the planets and which protects them from galactic cosmic rays, shrunk to less than the Earth’s orbit about 2-3 million years ago as the System passed through a Cold Cloud such as one they call the Leo Cold Cloud. “The extra cosmic rays could have had drastic effects on Earth’s climate and potentially on human evolution at that time, as suggested by existing data.”
* The More Metal, the More Wonderful?
As noted below in the Sky Planning Calendar, the Long Period Variable star (LPV) Mira, ‘the Wonderful’ in Cetus the Whale is on the rise to a peak brightness in mid-July. Officially Omicron Ceti, the star varies over a 332-day period, though that’s not always exactly true. It varies from dim 9th magnitude (8th to 10th are possible, too) and up to 2nd magnitude, though some have claimed 1st. The variability was first noted firmly in the late 1500s, but there are some hints people noted its strange behavior, but not a periodicity, in ancient Greek and Chinese times.
It is the first discovered of the so-called LPV or Mira variables, red giants with long pulsations that change its brightness. But not all Mira stars change in the same way. Is there anything that dictates the brightness or the periods of the variation? Are the two connected? It is well-known among astronomers that Cepheid variables, which are used as distance determiners and ‘standard candles’ in distant galaxies, have a period-luminosity relationships. Could something like that exist for Mira’s?
Katiya Fosdick , Luis Henry Quiroga-Nunez , Lorant Sjouwerman, the first at the University of Wisconsin-Madison, Madison, WI, and the latter two at National Radio Astronomy Observatory, Socorro, NM, took advantage of the large amount of data collected by the Gaia satellite and the Zwicky Transit Facility, a telescope in California used to record exoplanet transits, among other things, to investigate over 36,000 Mira variables within 2000 parsecs (over 3000 light years) of the Sun, gaining periods for most of them. Some of them had been more deeply researched than others, and that sample was checked against spectroscopic markers for initial mass, mass loss rate, metallicity, circumstellar envelope thickness, and luminosity. As far as they could determine, the only relationship they could find was that the period and luminosity were related to metallicity and circumstellar shell thickness, that is, how much metallic content (elements in the periodic table greater than helium) and material above the star’s surface, exist. So a star with a lot of post-nuclear fusion by-products and/or gas/dust shells above its photosphere will have a different brightness or period than stars will less of one or the other or both.
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Finally, a story from overseas….
* What Turned On the Universe’s Lights?
In the earliest times of the Universe, there were no stars, just a big hot primordial soup. At some point the soup thinned out and the universe went dark, at least until matter began to organize itself into stars and galaxies and such. At some point the Universe began to light up because there was so much high energy ultraviolet light that it glowed. That was expected to take place far enough away in look-back time so that the quantity z that is used in measuring red shifts is greater than or equal to 6. Here galaxies and quasars, active galactic nuclei, are so hot that they produce lots and lots of ultraviolet light, particularly Lyman-alpha radiation from hot hydrogen. This would radiate outwards and cause the so-called reionization of the cosmos. The question is, how much do each of these contribute. According to Chinese astronomers, the quasars , not so much, about 7%. All fireworks, no heat. (NatureAstronomy, 12 May 2022, L. Jiang et al.) https://doi.org/10.1038/s41550-022-01708-w
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.
Our evenings are almost planet-free, and all the Moon passages by planets this fortnight are in the dawn, but that makes it a great photographic experience, practically a Moon+planet every other night or so.
June 18 Saturn 4-degrees North of the Moon.
June 19 The minor (not dwarf) planet Vesta is 0.7-degrees North of the Moon, and gets occulted but only if you are near the Antarctic, southern Africa, southern South America part of the world. Let me know how it went….
June 20 Last Quarter.
June 21 Jupiter is 3-degrees North of the Moon.
June 22 Mars is 0.9-degrees North of the Moon and is covered by said Moon if you are in the South Pacific basin.
June 23 Today is the first of three straight mornings where the Moon is between Venus and Mars, standing in for Earth in the Grand Line-Up in the dawn. Also, if you look about 10-12 degrees due South (that’s to the lower-right in the eastern part of the sky) with binoculars you’ll see a barely naked eye red star. That’s Mira, the first discovered long-period variable star, namesake for the Mira-variables, red-giants that pulsate in a somewhat regular manner over about a year’s time from deeply invisible to, in this case, visibility. Mira can brighten to only barely visible 6th magnitude to blazing as a 1st magnitude star, every 332 days, though that’s not in precision like a clock either. (See the story above about research on LPV stars.)
June 24 Uranus gets occulted by the Moon for parts of Australia, the islands off southeast Asia, Polynesia, and as far east as Hawaii.
June 26 Venus is 3-degrees South of the Moon, Venus being to the right.
June 27 If you’ve ever had trouble finding the innermost planet, here’s your best chance. Find it 4-degrees South of the Moon, that is, Mercury is to the Moon’s right by that distance, i.e. 8 Moon diameters. (See the Cover Photo).
June 28 New Moon, and Apogee. If you could see it, it would be the smallest possible Moon in the sky you could see all year!
June 29 and 30. The thinnest lunar crescents possible pop up into the evening twilight. See if you can see them only 1 and 2 days old!
Observing---Plan-et….
The key planetary event that actually affects you this half-month is Earthly, the June Solstice. The Sun reaches its most northerly position in the sky at 4:14 AM CDT on June 21st. This is the longest day (in terms of solar radiation input) at 40-degrees north latitude, though not necessarily at all northern latitudes, and definitely not in southern! For northerners, the latest twilight in the evening is three days later, and latest sunset is six days after the solstice, both products of our planet’s tilt and orbital eccentricity changing our planet’s orbital speed.
As noted, all the visible (and not visible!) planets are in the dawn in a string of over 100-degrees in length. Thus you may think we are planet-less in the evening, but no…not if you stay up late enough.
Saturn already rises before local midnight now, in fact, by the end of the month, it rises by ~11 PM Daylight Saving Time. Jupiter will rise by midnight Standard Time (if you don’t do DST) around the 25th.
Mercury reaches its maximum distance from the Sun on the 16th, and after a few days lingering there it begins to fall back slowly towards ol’ Sol, but not too quickly. It will remain in view into early July, and brightening so enjoy the show. On the 24th, you’ll find it 3-degrees from reddish Aldebaran, in Taurus. Mercury sometimes is considered another red planet, though it really isn’t like Mars. This is a good chance to visually compare brightnesses and colors of Mercury with something of equal magnitude and “color”—and see if it is so (see the Cover Photo).
In the For What It’s Worth Department, at month’s end Jupiter is in the constellation of…Cetus, the Whale. As discussed in the latest issue of The Classroom Astronomer, while the planets may be lined up in order in the dawn, they aren’t lined up in a straight line nor exactly on the Ecliptic, the Sun’s path in the sky. In fact, all the visible planets are below the Ecliptic, and the various worlds can vary as far as just over 8 degrees in the case of Venus from the Ecliptic! That means planets can not only be in the 12 traditional zodiac signs (plus the two non-traditional ones the Sun goes through or touches—Ophiuchus and Cetus, respectively) but also TWELVE more! Mars trespassed in Cetus in the first half of June; above we’ve pointed you to Mira in Cetus, the Sun was there in March. Jupiter is just passing through.
Border Crossings
The Sun goes from Taurus to Gemini on the 20th, the day before the Solstice. The astrologers think it entered Cancer on the Solstice. Sigh….
The Classroom Astronomer Newsletter-Inbox Magazine #28 June 12, 2022 Issue Highlights.
Cover Photo - The Planetary Ecliptic Zone
Welcome to Issue 28!
Sky Lessons -Planets All In A Row in the Sky, and Out of the Ecliptic (and a ‘Wonderful’ Visit to Cetus)
Connections to the Sky - - A Space Game for Grandpa/Grandma? - Collated List of Model Solar Systems 1.0
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