The Galactic Times Newsletter #29 - August 1, 2022
Deeper Looks--Gaia, Future Space Missions for Habitable Moons, A New Arecibo; Sky Planning--Planets in the Evening, Saturn Up All Night, A Comet and Meteors, A Daytime Jupiter Challenge.
Cover Photo - Gaia, Cataloger of the Universe
In This Issue:
Cover Photo — Gaia, Cataloger of the Universe
Welcome to Issue 29!
Deeper Looks —
* AAS: The Future of Arecibo
* EAS: Gaia, Cataloger of the Universe
* EAS: Missions and More Missions
Sky Planning Calendar —
* Observing—Plan-et —
- The Evening Show Begins with Saturn at Opposition
- The Perseids and Comet K2
* Moon-Gazing - A Challenge to Use the Moon to Find Jupiter in the Daytime
* Border Crossings - Leo Overlaps!
The Classroom Astronomer Newsletter-Inbox Magazine #32 July 31, 2022 and #33 August 1, 2022 Issues Highlights.
Welcome to The Galactic Times Newsletter-Inbox Magazine #29 !
Don’t know why I didn’t think of this before, but I, as a writer, am thoroughly enjoying writing the Deeper Looks articles, and I hope you enjoy reading them. Makes attending many of the conference sessions worth the time! This issue, Deeper Looks looks at the future—Arecibo’s and European and habitability space missions, and the Gaia mission. We have more of these coming, and more This Just In stories in upcoming Galactic Times issues, don’t worry!
Observationally, try the challenges of finding Comet K2, and Jupiter in daytime!
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AAS: The Future of Arecibo
On December 1, 2020, to the complete surprise and shock of all present, the antenna and one of the towers of Arecibo Observatory (AO) suddenly crashed to Earth, also ripping into the reflecting dish that receives and focuses signals from space, utterly destroying it. Thus ended the nearly-60 year old storied and historic Big Ear that gathered information on worlds in our solar system and radio sources and stars in our galaxy. Only recently has it been surpassed in size as a single piece radio telescope, by a Chinese observatory.
What can be done to rebuild it, especially in these troubled times, with a pandemic, a hurricane devastated island, and economic and political troubles?
A US Senate Resolution was created on the one-year anniversary of the telescope’s collapse, and entered into the record on February 2022, unanimously supporting the rebuilding of the Observatory. How the National Science Foundation will get the funds for that is not clear, nor to what end.
Proposals for a new Observatory vary.
The new versions fall into three types. One is similar to the old Arecibo, though a bit more versatile. Where the old antenna had a limited range of sky it could view, as the reflector could not move and the aerial antenna had limited horizontal range, this one (the middle picture in the above diagram) has a more movable and aim-able secondary reflector, and a ground-level receiver, thus the combination could cover a wider area of sky. Another plan, of which the top diagram is just one suggestion, involves replacing the ground ‘mirror’ completely with a multi-mirror rotatable radio telescope in large scale, somewhat like some of the very large optical telescopes being built today. A final prototype plan is along the line of some of the current large dishes, including a large Chinese radio telescope, with an offset receiver and a completely movable dish.
There are good scientific reasons to rebuild Arecibo as quickly as feasible. AO was the largest facility involved in the Planetary Defense program, scanning the skies and examining objects that might approach the Earth dangerously and close enough to strike the planet; it has a Congressional mandate to identify and characterize Near-Earth objects. Existing worldwide radars can not keep up nor have enough capabilities to examine NEOs. Before its demise it was one of the leading facilities for pulsar studies, planetary surface studies, and gravitational wave studies. The facilities that are left can only handle, in some cases, only half the load. With telescopes like the Vera Rubin Observatory coming online, the amount of NEOs, for example, will get even greater, and more than the other facilities can study.
Meanwhile, Arecibo itself is still functioning in other ways, if not in active gathering of data. Scientists are still using its massive database of prior observations. In education, students still come to its visitor center and there are internships and other short and long term educational programs for students. But AO is not a museum or an archive by plan; it was a working observatory, and a needed one, and it will take years before it can be back online. The longer the funding is not flowing, the longer that reboot will take.
EAS: Gaia, Cataloger of the Universe
The first stellar distances were painfully and arduously done by eye measurements of its parallax, the shift of its position in the sky as the Earth moves from one side of its orbit to the opposite side. These were done with micrometers on telescopes, the devices used to measure the separations of binary star components. The first parallax measured wasn’t the nearest star, but 61 Cygni, by Friedrich Bessel in the late 1830s. Why? Because most astronomers were in the northern hemisphere, it was a moderately bright star, and it had one of the fastest proper motions—movement across the sky—so was presumed to be nearby. And it was, not quite 12 light years. The nearest star, Alpha Centauri in the Southern Hemisphere, at 4 light years, has a parallax only as large as a US Nickel seen from about 5 kilometers (3.3 miles) away. And that’s the largest! Over the next 100 years, the list of accurate (and that’s with a grain of salt) parallaxes was a bit over 100 stars. All others had high error factors, like 50% or more.
Imagine the inconceivable thoughts of Bessel and the early astronomers to the idea that we now have millions of accurate star distances, essentially using the same parallax method, only via observation from a single space satellite placed beyond the Moon! Shaped like a medieval Korean hat, with a wide brim, this satellite launched by the European Space Agency scans the sky with a multitude of sensors and has recorded a catalog of objects that dwarfs all prior efforts. As of June 2022 it has been in orbit for nearly 3000 days (~8 years), made 10^12 observations, and every day makes 70 million of them with each object getting 10 positional, 2 brightness and 3 spectroscopic observations in each transit through its view.
It recently released its third data compilation, each release of which are available to the world. At the EAS meeting in late June, Dr. Carme Jodi of the Gaia team gave a summary of the results that Gaia has found.
What it observes
Gaia observes three kinds of data: astrometry (positional), spectrophotometry and photometery (brightness) and spectroscopic (composition). The astrometric data is measuring the object’s position on the sky and determining parallax and proper motion from changes over time. The spectrophotometery records various brightnesses of the light in different colors and uses that for determining metallicity of the star, its temperature, brightness and its changes, age, dust effects, mass and color. The Photometry records radial velocity (speed towards or away from us) and rotational velocity around its own axis, and light of various possible elements in its spectrum.
What it observED
In its latest release, DR3, the tally is immense! There are 1.8 BILLION stars, 3 million galaxies, 2 million Quasar-stellar Objects (QSOs), and 156 thousand asteroids. Among the stars are 1.5 billion object classifications, 10 million variable star observations, 220 million spectra recorded and more than twice that in astrophysical quantities like mass, and 813 thousand binaries.
Among the variable stars…
…are over 15,000 Cepheids in and outside of the Milky Way—useful for distance measures, 2.2 million eclipsing binaries, 1.7 million long period variables, 214 planetary transits, 363 gravitational lensings, and more.
What’s between the stars…
Gaia has produced a map of the dust in the interstellar medium, and the first all-sky map of the 862-nm dust line.
…and in the solar system?
It has cataloged Mars crossing asteroids, Trojan belonging to Jupiter, Centaurs, trans-Neptunians, NEOs, and 31 moons, along with brightness, orbit and composition information for over 150,000 asteroids.
The future holds one or two more releases through 2030, when the mission likely will end.
EAS: Missions and More Missions!
In several different sessions speakers put up slides cataloging different missions, mostly to objects in the solar systems, including legacy, active and future missions. For your reference, here are the upcoming (mostly) European missions you should be aware of to each world:
… and space observatory missions.
What you are not seeing are some of the planned US missions, and the proposed missions to the outer worlds that are specifically designed to search for evidence of life, or at least habitability.
Speaking of which, what are the conditions of habitability? You need liquid water, minerals and nutrients, and energy. Where in the solar system can we find them? Life on other worlds, once conceivable searched for only on Mars (and still doing so), now includes searching some of the moons of Jupiter and Saturn. Orbiting the latter is Enceladus, a moon with geysers of water vapor indicating a likely ocean under the icy crust, with methane sources. Around Jupiter, Europa is similar (shades of Arthur C. Clarke’s “2010”!). Titan has always also held out the possibility towards some kind of life zone, and there are proponents for Ganymede and Callisto. So in addition to the JUICE mission shown on the graphic above, one should also keep in mind the American Europa Clipper and the Saturn-bound Titan Dragonfly (a helicopter mission!). Though not seeking life, there are a number of proposed missions to Venus and Mars not shown on the graphics either. But this is a start.
Sky Planning Calendar
Welcome to the opening of the evening planet show! If you are in the Southern Hemisphere, you are entering the best month this year for seeing Mercury, from now through end of the month. For Northerners, it is a meh experience. It sets about an hour after sunset from the 7th until the 18th, a tough call (but look for Mercury 0.7-degrees north of Regulus in the evening of the 3rd, the only good conjunction of sorts.)
Then, one after the other, you get the three visible outer worlds. In order….
First up is Saturn, in fact as of the 14th it will be up as soon as it gets dark and remain up until sunrise, Opposition Night! On that night the light you see left the planet 74 minutes earlier, it will be 8.86 Astronomical Units away from you and a bright magnitude +0.3 (not as bright as Vega but brighter than Altair, two of the three stars in the Summer Triangle—compare them!). The rings are tilted only 13-degrees so they are not wide open, and are 44-seconds of arc wide, a bit more than twice the planet’s diameter. It is the only bright star in the faint water zone of Capricornus and other nearby oceanic constellations. The Moon pays its respects on the 11th on its way to the East.
Jupiter rises at the end of twilight after the 16th, the day after the Moon passes by it. See below for a challenge!
Mars straddles the evening-morning line, rising at Daylight Time midnight around the 13th.
Venus, of course, holds down the fort in the dawn, with Saturn setting on the opposite side of the sky, and Mars peaking in the South between them. It no longer sets in darkness and in fact is starting its swan dive towards the Sun, to disappear in mid-September into the solar glare.
Let’s talk rocks and fluff….
The Moon will wipe out the good views of a comet, and the debris of a comet. The Perseid meteor shower will peak August 12th evening, North America time, a day after the Full Moon, which essentially wipes it all but out. Your best views will be the last hour or two before dawn on the 13th when the Moon is low or gone and you might just get up to 60 meteors in an hour. Otherwise, most of the cosmic chalkmarks in the sky will be jet contrails. But you can see some and at least it will be warm, unlike watching the December Geminids.
Meteor showers are the debris of comets’ prior passages. We have a comet making a first-time passage now, C/2017 K2 (PanSTARRS). It is a bit unusual, having been detected much earlier than normal and, depending on the calculations, it may have a larger than average nucleus (there is some disagreement on that). So it is getting a lot of unvetted social media buzz with images of huge tails and near-Earth disaster talk that are totally unrealistic. Unlike meteors which move rapidly across the sky, comets rarely move fast even when watching over an hour in a telescope! This one….a poor tail that will be as masked by the moonlight as the Perseid meteors and will move only around a degree or two per week (i.e 2-4 moon diameters). You’ll find it on Perseid peak night just above the head of the Scorpion.
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.
The evenings of the first half of August are neither planet-free nor Moon free, though the two are not yet much entwined. The Moon is, however, interfering with viewing two other solar system objects…..as noted above.
August 5 First Quarter.
August 10 Perigee. A Super Very Gibbous Moon!
August 11 A night of oppositions, sort of. First, the Moon is in opposition to the Sun, i.e. Full Moon, 180-degrees from the glowing orb, the Earth in the way (well, almost, no eclipse this month, wait three more months….) on the midnight between the 11th and 12th, East Coast USA time. You’ll find Saturn 4-degrees north of this last Man-in-the-Moon’s-Face-Before-School-Begins opportunity. Second opposition is Saturn, technically 3 days from now but close enough!
August 14 This is a hard one, but….dim Neptune is 3-degrees north of the Moon. Good luck, use a good scope. Don’t look at the Moon first or you’ll lose the night vision you need to see the faint planet.
August 15, daytime. Jupiter is 1.9-degrees north of the Moon. Can you find it with binoculars, or even your unaided eyes?
The newspapers say this is Leo’s time. Astronomically, the Sun doesn’t enter Leo until the 10th. Astronomy and Astrology will coexist for almost two weeks afterwards!
The Classroom Astronomer Newsletter-Inbox Magazine #32, July 31, 2022 Issue Highlights
Cover Photo - Near-Earth Asteroids Students Can Research
Welcome to Issue 32!
Astronomical Teachniques -
- NAM: How NOT to Do Tactile Astronomy
Astronomy Remotely —
- RTSRE: Astronomy Learning for Neophytes Part 2 — LCO
Connections to the Sky -
- First Webb Photos’ Look-Back Times and Distance
- AAS: Planetary Radar for Students
- AAS: Summer Internships in Astronomy Research
The Classroom Astronomer Newsletter-Inbox Magazine #33, August 1, 2022 Issue Highlights
Cover Photo - Finding Comet K2
Welcome to Issue 33!
Sky Lessons - The Difference Between Comets and Meteors
Astronomical Teachniques - NAM: A Course on Cosmic Clocks
Astronomy Remotely - Thoughts to Consider from the Robotic Telescope Science Research and Education Conference (for courses that use Robotic Scopes, and those that don’t)
Connections to the Sky - NASA Goddard’s 2022’s Greatest Hits
The RAP Sheet -
- Observation of Libration and Change in Apparent Diameter of the Moon with a Pinhole Camera
- Evaluating the Content Accuracy of Augmented Reality Applications on the Solar System
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