Three different space missions offer spectacular views of Christmas Comet A1 Leonard.
NASA’s new Sentry II system will refine long term collision predictions for Near Earth Asteroids.
NASA has a powerful new tool in its arsenal for defending the Earth from hazardous asteroids. Since 2002, the space agency has used the Sentry system to predict the future path of near Earth asteroids (NEAs), and assess their risk for a potential future impact with the Earth. This system, however, has its limitations. As the number of known NEAs nears 28,000 and grows by 3,000 new asteroids per year, a new system is needed to keep up with demand.
The new system named Sentry II will meet this need. Sentry II just went online in December 2021, and will use an enhanced algorithm to look at all of the factors impacting an asteroid’s future trajectory. Astronomers expect to see better, more accurate projections further into the future, using the Sentry II system.
Sentry’s Original Limitations
NASA’s Center for Near Earth Object Studies (CNEOS) based out of the Jet Propulsion Laboratory in Pasadena, California works together with the agency’s Planetary Defense Coordination Office (PDCO) to assess impact probabilities over the next century. The system could run the predictions in under an hour, a vital resource especially in terms of seeing small asteroids inbound, which are often discovered with little advance warning. A good example was the Chelyabinsk impactor which struck Russia the day after Valentine’s Day in 2013. The Chelyabinsk rock came at Earth from a sunward direction, and was undetected prior to impact.
However, the original Sentry system had its drawbacks. Asteroid path predictions are limited by the number of observations made: the more observations, the better we know its future path. Not only does this path become more indefinite over time, but small tugs by other planets in the solar system perturb an asteroid’s path. Sentry accounted for this, but it didn’t factor in the complex effect of thermal heating from the Sun via what’s known as the Yarkovsky effect, which slowly nudges an asteroid over time. Small changes add up, and Sentry II will take these into account.
“The fact that Sentry couldn’t automatically handle the Yarkovsky effect was a limitation,” says Davide Farnocchia (NASA-JPL) in a recent press release. “Every time we came across a special case—like asteroids Apophis, Bennu or 1950 DA—we had to do complex and time-consuming manual analyses. With Sentry II, we don’t have to do that anymore.”
The previous method would often break down—especially in the case of close Earth flybys—requiring manual analysis of the future trajectory of the asteroid. Sentry II eliminates this with a different mathematical approach, allowing it to focus in on low probability impact zones (known as keyholes). These are regions which would made a future impact more likely, were an asteroid to pass through these narrow zones.
Sentry II is vital, as new all-sky surveys such as the Vera C. Rubin telescope come online over the next few years. Expect to see a flood of new discoveries of ever smaller asteroids, necessitating the need for a more powerful prediction model such as Sentry II.
101955 Bennu and 99942 Apophis are good case studies in narrowing down the uncertainty of a future impact. Discovered in 2004, 450 meter Apophis generated a brief amount of excitement when it looked like there was a small chance of impact with Earth on April 13 (yes, Friday the 13th) 2029. Better observations and predictions soon ruled this out, though there was still a small chance of an impact later this century in 2068, though that was also ruled out earlier this year.
Thanks to the OSIRIS-Rex mission, we now know the orbit and characteristics of Bennu better than any other asteroid in the solar system. This 530-metre space rock has a small (1-in-2,700) chance of impacting the Earth on September 24th 2182, if it happens to pass through a gravitational keyhole in 2135.
But NASA isn’t just passively hunting for asteroids. On November 24th, the agency launched the Double Asteroid Redirection Test (DART) mission headed towards double asteroid Didymos, where it will impact the asteroid’s tiny moon Dimorphos in late September-early October 2022. This exercise, coupled with the Sentry II system may prove useful, if we ever did need to move a potentially hazardous asteroid out of harm’s way.
A unique circumbinary exoplanet system transits both host stars.
The menagerie of exoplanets just got a little stranger. Add to the fastest, hottest etc… a new find: TIC 172900988 b, a circumbinary world that transits both host primary stars.
Eclipsing binary stars are well known to astronomers: two famous stars, Algol and Beta Lyrae are naked eye variables, dimming and brightening as they happen to pass one in front of another. The same method also works to tease out unseen companions: exoplanets are discovered as a world passes in front of its host star as seen from our line of sight, creating a tiny dip in its brightness.
Circumbinary exoplanets—planets orbiting two stars—have been seen before: the first circumbinary exoplanet discovered was PSR B1620-26 in 2003, and the Kepler Space Telescope found about a dozen of such worlds out of the thousands of exoplanets it discovered. Its successor, the Transiting Exoplanet Survey Satellite (TESS) has found 3,500 exoplanet candidates and more than 150 confirmed worlds and counting since its launch in 2018.
But what they saw in the light-curve of TIC 172900988 b gave astronomers pause. In addition to the expected dip from the tight orbiting primary pair, they caught a double dip about five days apart, as the 2.8x Jupiter mass world transited one star, and then another.
This is a surreptitious find, as TESS only had a 30 day window to observe this patch of sky. This also enabled astronomers to extrapolate the planet’s roughly 200 day orbit around the primary pair using the short observation arc, another first.
The two host primaries are solar mass, G-type yellow dwarfs like our Sun. The world would probably be a scorcher on the inner edge of the system’s habitable zone, but if, like Jupiter, TIC 172900988 happens to possess large moons, there’s always a chance that they’re partially sheltered inside the giant planet’s magnetic field.
The system is located 246 parsecs distant in the astronomical constellation Cancer the Crab, shining at about 10th magnitude. High-resolution imaging in the near infrared part of the spectrum also revealed a possible red dwarf companion in the system, on a wide-ranging 5,000 year orbit.
The last few decades of exoplanet discovery has revealed just how bizarre other solar systems can be. It’s amazing to think: back until the discovery of pulsar planet system PSR B1257+12 in 1990, no exoplanets were known of… and I remember astronomers in the 1980s making the argument that it might just stay that way, as exoplanet detection is just too difficult. Fast-forward to the end 2021, and we now know of 4,890 worlds in the catalog and counting.
And our fair world also transits from the point of view of any known exoplanet along the plane of the ecliptic as well. It’s been proposed that any worlds found along the ecliptic plane would be excellent targets for a SETI search, as they would probably know we’re here, too.
Add just one more interesting world to the catalog, in the ongoing golden era of exoplanet astronomy.
What are the top astronomy events you can observe in December 2021? December sees Comet A1 Leonard at dawn, and the promise of the bright winter hexagon rising at dusk.
The month of December 2021 brings us home, in more ways than one. Yes, it’s the end of the calendar year. It’s also time for the southward solstice, marking the beginning of astronomical winter in the northern hemisphere, and summer in the southern. But it also marks the return of the Winter Hexagon asterism to the evening sky. So let’s dive into the topic and let’s check out what the top astronomy events for December 2021 are!
The December Sky
Going clockwise from the top, the members of the Winter Hexagon are: Capella, Aldebaran, Rigel, Sirius, Procyon, and the twins Pollux and Castor. Sirius is the brightest star in the sky, and sits due south at midnight on New Year’s Eve. You can tell the twins apart by remembering ‘P’ollux is on the same side as ‘P’rocyon, and ‘C’astor is on the same side as Capella. Betelgeuse tops of the scene, near the center of the hexagon.
There’s a reason that so many bright stars dominate the December sky. That’s because you’re looking outward from the core of our Milky Way Galaxy towards the Orion Spur, passing through the constellation of the same name. Our Sun is embedded in the Orion Spur, along with the bright December stars in the same direction. In fact, the Galactic Anti-Center is off in the direction of Gemini, very near the open star cluster Messier 35.
In the southern hemisphere, the evening sky in December sees the parade of nearby bright stars continue through Canopus, Achernar and the famous ‘Southern Cross’ Crux riding high to the north near midnight. To some, just spotting the swayback cross of the Crux is the highlight of their astronomical life-list on a journey to the southern hemisphere.
Fun fact: The International Space Station has an orbital inclination of 52.5 degrees meaning that near either solstice, it can enter a period of full illumination, making for multiple bright passes a night worldwide. December favors the southern hemisphere, and in 2021, we enter a six day span of full illumination for the station starting on December 11th.
The Moon in December 2021: The Moon reaches New phase (witha total solar eclipse passing over Antarctica) on December 4th, and reaches Full on December 19th. This is also the most distant or smallest Full Moon of the year (a MiniMoon), and the Long Night’s Moon closest to the December Solstice.
The planetary rundown in December 2021: Venus, Jupiter and Saturn are lined up at dusk, with lonely Mars reemerging low at dawn, and Mercury near the Sun emerging at dusk in the last week of 2021.
The waxing crescent Moon pairs with Venus on December 7th, marking the start of a great series of passes as it slides by Mercury, Venus, Saturn and Jupiter over the course of the week.
December meteors: The December Andromedids—once a great shower in the 19th century that fell into obscurity—may be making a comeback in 2021. Certainly, it’s worth watching for the elusive shower, with the Moon near New in the first week of the month. December is also time for the dependable Geminids, which peak with an expected Zenithal Hourly Rate (ZHR) of ~150 for 2021, on the night of December 13th/14th, five days prior to Full Moon. Finally, watch for the 2021 Ursid meteors on the night of December 22nd, with an expected ZHR of 10-20, three days after the Full Moon, and just three days before Christmas.
Comets: The first week of December is a great time to nab comet C/2021 A1 Leonard as it begins its plunge sunward. As of writing this, the comet is shining at magnitude +7.5, placed high in the dawn. The comet passes 0.233 Astronomical Units (AU) from the Earth on December 12th and reaches perihelion 0.62 AU from the Sun on January 3rd 2022, exactly one year after discovery. Follow the comet on the morning of December 3rd, when it makes a fine pass near the globular cluster Messier 3 just 12’ apart. The comet might top out at magnitude +4 or so, before we lose it in the dawn by mid-month.
Deep Sky highlight (northern hemisphere) Exploring the Orion Nebula Complex – The Pommel of the sword of Orion just below the belt contains one of the very few nebulae just visible to the naked eye. This is Messier 42, the amazing Orion Nebula. Even in the low power field of view of binoculars or a small telescope, M42 is a fine object, looking like a paper lantern lit from within. This metaphor is apt, because M42 is actually a stellar nursery containing massive stars just starting to shine, blowing back curtains of gas and dust in the process. Crank up the magnification, and you can see a grouping of these young stars near the center of M42, known as the Trapezium. M42 is actually the closest stellar nursery to our solar system, at ~1,300 light-years distant.
Deep Sky highlight (southern hemisphere) – The Winter Albireo: everyone knows the northern colored double star Cygnus in the tail of Cygnus the Swan… but did you know that there’s a lesser known southern counterpart? Herschel 3945 is in the constellation Canis Major, and possesses two +5th magnitude stars, one blue and one orange-gold. It actually forms an equilateral triangle with Omicron Canis Majoris 2 and Delta Canis Majoris (Wesen), and really pops out in a binocular field of view. The pair are 27” apart, and about 1,400 light-years distant.
Challenge object (northern hemisphere) – One of the brightest stars of the December sky is also and amazing multiple system. Castor is an easy split of two +3rd magnitude stars, 5.3” apart. I’ve heard folks at star parties say that Castor looks like a far-off set of car headlights in the telescope. Now, see a +9th magnitude star, 72” away? That’s a red dwarf system, physically related to the central pair… but each of these three stars are actually spectroscopic binaries (resolvable via the intertwined spectra of the stars), for a total of six stars in the sextuplet system.
Challenge Object (Southern Hemisphere) Can you spy Sirius B? Ever seen a white dwarf? The brightest star in the sky Sirius possesses one, though its a bashful find. Shining at magnitude +8.7, Sirius B wouldn’t be a tough find… were it not for the dazzling nearby primary, about 10,000 times brighter. On a 50 year orbit, 2021-2022 is a great time to try and spy this elusive white dwarf as it just reached apastron in 2019 at 11” arcseconds distant from its primary. The maximum apparent separation as seen from the Earth is 11.3” in 2023. good luck!
Top Astronomy Events for December 2021
1/14-Comet 2021 A1 Leonard best at dawn
4-Moon occults Mars for NE Asia (1% illuminated waning crescent Moon)
4-New Moon+Total Solar Eclipse for Antarctica
4-Moon occults Mercury for S. America+Africa in the daytime(1% illuminated waxing crescent Moon)
11-Venus passes just 3’ from 14th magnitude Pluto
19-Full Moon (smallest of the year)
22-Ursid meteors peak
31-Moon occults Mars for SE Asia (6% illuminated, waning crescent Moon).
We hope that this top astronomy events for December 2021 will bring many enjoyable observing times for you. Clear skies.
Vaonis observation stations are closed-tube instruments unlike conventional main mirror telescopes with open tubes. This makes them less fragile and easier to maintain. There is less risk of dust getting into the tube, the optical system is better protected and the mirror does not need to be aligned regularly to maintain performance, even after being moved.
Two accessories are available for transporting your Stellina:
Ideally, the front lens should be cleaned as little as possible. It is sometimes preferable to leave some dust or very light traces rather than risk a hazardous manipulation which could damage it. Avoid contact with fingers to avoid leaving greasy marks and with abrasive objects to avoid scratching. It is possible that some dust may be present inside the optical tube. This does not affect the performance of the observation station.
If, despite your precautions, dust or greasy marks become a nuisance, here’s how to proceed:
A low-cost project named SISTINE could create a baseline index in the search for life on other worlds.
In astronomy, small missions can have a huge impact. And while huge projects such as the James Webb Space Telescope launching next month took over a decade to get to the launch pad and cost tens of billions of dollars, balloon-based or sub-orbital rockets offer a quick low-cost alternative to get telescopes up over the murk of the lower atmosphere.
Just such a mission launched early this month, from White Sands New Mexico. SISTINE-2 (the Sub-orbital Imaging Spectrograph for Transition region Irradiance from Nearby Exoplanets) launched on November 8th on a Black Brant IX rocket. During its 15 minute flight, the project reached an apogee of 160 miles, successfully collected data, and was later recovered.
SISTINE looks at celestial targets in the ultraviolet (UV) at the 100 to 160 nanometer wavelengths. On the ground, most UV at this wavelength is absorbed by the Earth’s atmosphere. Some of the very first ‘space telescopes’ were carried aloft by sub-orbital rockets, starting with UV views of the Sun using a captured German V-2 rocket in 1946. The first SISTINE launch occurred in 2019.
SISTINE uses a unique lithium fluoride coating to make its mirrors sensitive at UV wavelengths. These UV wavelengths are key in seeing the breakdown of carbon dioxide molecules into free oxygen. On Earth, life has reworked to atmosphere, and the presence of molecular oxygen or ozone elsewhere could be a strong indicator of life. Stars, however, may also shed energy at the same wavelengths, resulting in the same sort of breakdown and confounding the search with spurious signals.
What the SISTINE project hopes to do is it create an index catalog for main sequence stars in the Morgan-Keenan classification scheme, as a way to sort out bio-signatures versus baseline signals.
“The interplay between the planet’s atmosphere and ultraviolet light from the host star determines which gases serve as the best biomarkers,” says Principal Mission Investigator Kevin France (University of Colorado) in a recent press release. “Knowing the ultraviolet spectra of these stars will help us find the most promising star-planet environments with future NASA observatories.”
The recent target for the SISTINE-2 launch was Procyon A, the brightest star in the constellation Canis Minor, 11.5 light-years distant. Though Procyon A is an F-type star slightly hotter than our Sun and hosts a white dwarf companion, it does not possess any known exoplanets.
The findings for the SISTINE project could go a long ways towards the ultimate goal of finding an exoplanet that has life. Next summer, the team plans to carry out a third launch from the Arnhem Space Center in Nhulunbuy, Australia. The southern hemisphere vantage point with afford the SISTINE detector views of the Alpha Centauri system with G- and K-type stars primary stars, as well as the red dwarf Proxima Centauri, known to possess the closest known exoplanet.
Exoplanet science could get interesting in the next decade. The recent Decadal Survey for Astronomy and Astrophysics announced plans for a 6-meter space telescope as the next true successor to Hubble, a sort of compromise between the proposed LUVIOR (the Large Ultra-Violet Infrared Optical Surveyor) and HabEx (search for Habitable Exoplanets) telescopes. Such an instrument could do an unprecedented survey of the sky at UV wavelengths, to include stars with known exoplanets and perhaps, life.
We could be on the brink of the discovery of life elsewhere in the universe in coming decades, and SISTINE could help pave the way.
An ambitious mission to the Martian moon Phobos may also snag samples from the Red Planet.
The race is on, in the coming decade, to bring back samples of the planet Mars to Earth for study. And while China has its Zhurong rover exploring the Martian surface and NASA’s Perseverance rover is actively collecting samples in Jezero crater for a sample return mission sometime in the 2030s, the Japanese Aerospace Exploration Agency’s (JAXA) Mars Moon eXploration (MMX) may actually beat them all to the punch.Read more
A novel twist on a proven method to find exoplanets yields a distant and strange world.
We live in a golden age of exoplanet discovery. In just under three short decades, we’ve gone from an era where no planets were known of beyond our solar system, to a wonderfully strange menagerie of 4,868 known worlds and counting. Now, to this list of ‘hottest, fastest, densest, etc,’ we might just be able to add another first, with the discovery of the first world known to exist beyond our galaxy.
The detection came from a tried and true method, employed in a unique fashion. Missions such as NASA’s Kepler and TESS (the Transiting Exoplanet Survey Satellite) use what’s known as the transit method. This is done by looking to detect an unseen planet as it passes in front of its host star, slightly dimming its light output in a predictable fashion. Of course, most orbits aren’t aligned to our line of sight, meaning that the transit method preferentially detects ‘hot Jupiters’ on fast orbits close to the target host star.
Astronomers realized that the transit method could also be used on distant targets, were the compact illumination source was sending out a large amount of x-rays. Such a system would host either a black hole or pulsar in a tight orbit around a massive star, drawing away material and emitting copious amounts of x-rays.
In the study, astronomers used the Chandra X-ray observatory to look at 55 systems in the M51 galaxy, 64 systems in M101, and 119 systems in M104. They hit pay dirt with a brief x-ray transit in the Whirlpool galaxy Messier 51 (Messier 51).
“We are trying to open up a whole new arena for finding other worlds by searching for planetary candidates at x-ray wavelengths,” says Rosanne Di Stefano (Center for Astrophysics at Harvard and Smithsonian) in a recent press release, adding that the “strategy… makes it possible to discover them in other galaxies.”
The bizarre world, known as M51-ULS-1, seems to be a Saturn-sized planet, orbiting a binary pair consisting of either a black hole or a pulsar in a tight orbit around a main sequence star, 20 times as massive as our Sun. Not only must the world host a strange-looking sky, but it must have had a tumultuous past, as the survivor of a cataclysmic supernova that spawned the black hole or pulsar near the system’s center.
The sad fact is though, the system may never be confirmed, or at very least, confirmation may be a long time coming: M51-ULS-1 is on a projected 70 year orbit, meaning we may not see the planet transit in front of the system’s x-ray jet until the end of this century.
“Unfortunately, to confirm that we’re seeing a planet we would likely have to wait decades to see another transit,” Nia Imara (University of California at Santa Cruz) said in a recent press release. “Because of the uncertainties about how long it takes to orbit, we wouldn’t know exactly when to look.”
Spotting Messier 51
You can see M51 for yourself: the +8.4 magnitude galaxy is a fine deep-sky object. Though I always know to look for it just below the end of the handle of the Big Dipper asterism, it actually lies just across the border of Ursa Major, in the constellation of Canes Venatici. The Earl of Rosse first noted the ‘nebula’s’ spiral structure in 1845, using the massive 72-inch (1.8-metre) Leviathan of Parsonstown telescope in Ireland, then the largest telescope in the world. Messier 51 is 31 million light-years distant.
The discovery, though a fleeting a tantalizing one, shows that such an exotic method for remote exoplanet detection is possible. Chandra and the European Space Agency’s XMM-Newton X-ray mission have produced a treasure trove map of the x-ray sky, a database that may well contain more transiting exoplanets… and last week, the Decadal Survey for Astronomy and Astrophysics announced that one of its smaller explorer missions on the community’s wish list is Lynx, a more powerful successor to Chandra.
One thing’s for sure: it’s a big Universe. What other exoplanets are out there in the data, awaiting discovery?
November sees the end of the transition from looking inward, to looking out of our Milky Way Galaxy.
You couldn’t ask for a better month to observe the night sky. Nights are getting longer up north and coming earlier as we ‘fall back’ to Standard Time, and Spring is still in full swing down south.Read more
Watch how the weather should evolve over the next few hours and days, directly from Singularity. You can also consult information on sunrise and sunset times and moon phases. This offers the essential elements for finding the best time for observation, all at a glance.
To make sure you don’t miss any important astronomical events, Singularity presents a summary of upcoming phenomena to observe. You can also access a complete article on the sky for the current month. Singularity also offers articles on astronomy or space exploration news.
From Singularity, you can access articles published on the Vaonis website which offer you tips on how to get the most out of your observation station, tutorials on image processing, and much more besides.
Singularity can save all your favorite observation sites for faster initialization of your observation station, showing you the prevailing conditions at each of them.
The first time you launch the application you must create at least one observatory. If you have registered several observation sites, to initialize your telescope simply choose the corresponding observatory and tap the “Initialize” button.
If you use multiple devices to connect to your observing station, your observatories will be shared among all your devices.
When choosing your observatory, you will also be able to use the new “Plan my night” feature according to the visible stars (see below for information on this module).
What is the temperature of my instrument? How much space is left on my USB key? What files are saved on it? Who are the other users connected to my telescope? All these questions are answered in a new screen that shows the status of your observation station. You may also use this screen to put your instrument to sleep when you have finished your observations or, for experts, access commands to capture calibration images (see below for more details).
A new section also allows you to store manual targets that you can point to by entering their coordinates.
Use this section to capture images of the stars using custom camera settings. Your settings are saved with the object. You can easily restart a capture session with the same settings (Expert Mode must be enabled, see below).
Various interface improvements have been made to facilitate exploration of the celestial object library. You can now consult at a glance the position in the sky of the objects directly from the catalog and do a search by constellation name.
Eagerly awaited by advanced users, Singularity offers the full power of the “Expert Mode”.
To activate this mode, go to the “Profile” screen, then in the menu at the top right, choose “Settings” then “Activate expert mode”.
When the Expert Mode is activated, you can capture images of the stars by adjusting the unit exposure time and the camera gain. The exposure time can vary between 5 and 20 seconds and the gain between 0 and 27dB (default values are 10 seconds and 20 dB).
Keep in mind that the default exposure time and gain values were established after extensive testing to achieve optimal performance in most situations.
However, there are some cases where you might want to change the default settings: for very faint objects if you observe under a sky of particularly good quality, for stars with strong contrasts in brightness (for example the Orion nebula), for very bright objects such as star clusters…
You can experiment with the optimal settings for you!
When you activate the recording of raw images (FITS format) on the USB key in order to perform manual stacking for image processing, we recommended also capturing calibration images (“darks” and “flats”) which allow you to “subtract” any defects inherent in the sensor and optics from the image of the object.
Singularity now officially supports this feature: from the status screen of your observation station, by tapping the “Expert Mode” button you can launch image acquisition while the optical tube is obstructed. You can define the camera settings and the number of images you want to capture and then let Stellina / Vespera do the work.
With “Plan My Night” you can take advantage of all the nights that are suitable for observation until daybreak without having to stay up behind the screen of your smartphone.
You can prepare your observations in advance if, for example, you are receiving friends or in the framework of an association’s activities. If your goal is to accumulate many captures of certain objects for image processing, you can let your observation station work while you sleep.
From a date and an observatory, create a program with a list of objects to observe. Set the dedicated observation time for each object. Activate the program on your observation station and Stellina / Vespera will start the sequence at the scheduled time following the instructions you set.
You can always follow the progress of your observation program in Singularity and interrupt it if you want to take over.
Singularity offers different filters to find the objects to include in your observation program: height on the horizon, duration of visibility, type of object…
Save your photos in your Singularity gallery and now find them on both your tablet and smartphone. Photo storage in the app is now synchronized across all your devices.
If you’re stuck for inspiration on what to target, want to be guided, or perhaps discover items you didn’t know, start a random observation from the home screen.