Sadly, there will be no Open Nights conducted at Stephens Memorial Observatory until further notice. As we write this, the only recommended means of preventing spread of the new coronavirus (COVID-19) is to maintain at least six feet of distance between each other. Inviting the public to share the crowded space beneath the observatory’s ~16-foot dome would not be wise in view of the risk. We do not expect to conduct any Open Night sessions this year. Until we meet again, please watch this website for other news and follow us on Twitter. Thank you for your interest!
The talk amongst stargazers this summer has been the apparition of C/2020 F3 NEOWISE in Northern Hemisphere skies. Previously one comet had caused excitement over its potential showing but it broke up as it approached the Sun. Another fizzled and faded from view. But C/2020 F3 survived its July 3 close approach to the sun (perihelion) and emerged bigger and brighter than expected.
The comet’s brightness is due to its large nucleus — the head of the comet — which is the source of frozen gas and dust that produces the visible tail or coma. “From its infrared signature, we can tell that [the nucleus] is about 5 kilometers across,” said Joseph Masiero, NEOWISE deputy principal investigator at NASA’s Jet Propulsion Laboratory.
C/2020 F3 was discovered in infrared images captured by NASA’s NEOWISE spacecraft in March 2020. The object was assigned the unromantic designation of C/2020 F3 with the spacecraft’s name as discoverer.
Falling in from the outer solar system, then diving perilously close to the Sun gave our comet a boost in speed and increased its orbital period from about 4,500 years to about 6,800 years — a long time to wait for its return.
Until recently C/2020 F3 put in its appearances only in the predawn hours, rising a little after 3:30 AM and fading into the brightening sky a bit past 5:00 AM. It was also rising to only about 10º above the horizon placing it, much of the time, in the realm of morning clouds, mists, haze, and general murk.
But it’s not over.
While at the time of this writing C/2020 F3 continues to be viewable in the wee hours before dawn in the northeastern sky, sinking lower with each morning, it is now also showing in the post-sunset twilight. It’s still only becoming visible around 14º to 10º above the north-northwestern horizon as it sinks toward the horizon following the Sun. The comet sets around 12:30 AM.
Evenings, for the next couple of weeks and possibly into August, go comet hunting! Depending upon whether the sky is clear of obstructions, clouds, and haze, skywatchers may be able to see the comet with unaided eye. Good binoculars will help in finding it and will give seekers a better view. The comet will be very low to the horizon so an elevated location will aid in viewing. Use binoculars to look west and then past northwest in the deepening twilight, scanning slowly and just above the horizon. The comet will appear as a vertical streak with a bright dot at the lower end, as in the picture at the top of this page. It may not be spectacular but how many comets does one see in their lifetime?
Our outbound visitor from outer space makes its closest pass by Earth on July 23 when it will be 103.7 million kilometers — about 64 million miles — away returning in roughly 7,000 years.
There was much ballyhoo surrounding the penumbral lunar eclipse that would take place the night of July 4 – 5, 2020. We joined in just to explain a little about what was going on and what might be expected. Penumbral lunar eclipses take place when the Moon passes through the thin outer shadow Earth casts out into space; they are often very subtle, slight, and in this case, nearly undetectable. Just witness the photo above that shows the Full Buck Moon about one-half hour before maximum eclipse and the Moon at maximum. Casual observers saw no change across the entire event and it’s hard for us to see the difference even in photos that can be made to emphasize features! So we apologize if you waited up to see what we called the “subtle” eclipse but, if you did, you saw a beautiful Full Moon!
Then there was the much-less-promoted Sunday night, July 5, conjunction of Earth’s Moon, with planets Jupiter and Saturn… a lovely sight! We went out to photograph it an hour after moonrise and spied a brilliant orange Moon lighting up the scattered clouds with Jupiter shining through and Saturn making a somewhat dimmer appearance. A conjunction is when two or more celestial objects appear close together in our skies — emphasis on appear since Moon, Jupiter, and Saturn are separated by hundreds of millions of miles. We were surprised to see, in the photo below, that even Jupiter’s four Galilean Moons can be seen. The stars and planets appear oblong or as short streaks due to Earth’s rotation and the length of the camera exposure.
Following Saturday night’s penumbral lunar eclipse, Earth’s Moon will get together with two planets in a lovely conjunction Sunday night, July 5. Any time from about 10:30 PM EDT and later, look to the Moon, big, bright and round just past its Full phase. Above and to the left and right of that bright orb will be two bright star-like objects. On Luna’s left is planet Saturn and above and just to the right floats brilliant Jupiter.
Both Saturn and Jupiter are approaching their opposition — the point in their orbits where each planet will be exactly opposite the Earth from our Sun. Opposition also places a planet about as close as it can be to us making it easier to see in detail, and brighter in our night skies.
Jupiter achieves opposition on July 14, while Saturn reaches its on July 20. The change in distance between Earth and the two gas giants is relatively slow giving casual observers plenty of time to enjoy the close-up view through their telescopes; a week or so before or after opposition really makes little difference.
Binoculars or a small telescope will allow users to view Jupiter as a bright dot with its four companion Galilean Moons. It’s helpful to have either a tripod mount or a way to brace binoculars when looking at Jupiter as it’s hard to hold steady enough for good viewing without!
Small telescopes with a bit more power will allow viewers to see the major cloud bands of Jupiter’s atmosphere and those same four moons. Make note of the position of those moons and take a look night-to-night or even after a couple of hours in the same night and you will see what Galileo observed: that those little star-like dots move!
Turn that telescope to Saturn and enjoy a look at the planet’s distinctive rings; they are well-positioned for viewing this month. If seeing conditions are good and with enough magnification, viewers can observe a dark line running inside the rings, a gap called the Cassini Division. It should also be possible to see the gap between the rings and the planetary body.
Both Jupiter and Saturn are bright enough that the waning Gibbous Moon shouldn’t interfere much with observing. Fear not, however, our Moon and those planets part company over ensuing nights providing a darker background. Jupiter and Saturn should be in a good position for observing any time after about 10:30 PM all month so you won’t have to stay up very late to enjoy the view.
We’re fortunate that the night of July 4 is expected to be clear, and not just for the traditional booms and flashes of celebratory fireworks. Our Moon is getting in on the act, albeit with a much more subtle display in the form of a penumbral eclipse. The eclipse will take place from 11:07 PM to 1:52 AM EDT with maximum eclipse at 12:31 AM July 5.
We say subtle because, unlike a total lunar eclipse, Earth’s Moon will not change to reddish/coppery colors. The Moon will instead become oddly shadowed for a Full Moon, as it enters the outer fringes of Earth’s shadow in space — the penumbra. Only the “top” portion of Luna will pass through the penumbra making this eclipse especially slight. Still, it’s worth a look and it won’t be at a particularly late hour. A deeper penumbral lunar eclipse will take place the night of November 30, 2020.
While it’s possible to view this eclipse with the unaided eye, binoculars will provide an enhanced view as would a small telescope.
And just in case there’s any confusion, lunar eclipses are perfectly safe to view and photograph — it’s moonlight — so nothing to worry about there.
If you shoot any photos or have impressions to share with us, you can do so via our Twitter — @StephensObs
NASA Eclipse Page available here: Penumbral Lunar Eclipse of July 4 – 5, 2020.
Can you see the comet named SWAN? The answer is, with luck, maybe. If we wish to see Comet SWAN, we’ll want some clear nights coming in the next week or so. Here’s a chart with hand-drawn positions of C/2020 F8 (SWAN) over the next month. June 2 would be our best opportunity as the comet will be highest above the horizon and near the star Capella, which will help in finding it. Getting the timing right will be challenging, between twilight fading enough for the faint object to be seen and spotting it before the comet sets! You’ll still need good binoculars to see this one and a clear view to the northwestern horizon. Place your order now for clear skies to be delivered the night of June 2 … DO IT NOW! Supplies are limited.
Comet SWAN has been a Southern Hemisphere object until just recently. I’ve heard some people here, up north, have caught glimpses of the comet already though it’s so low to the horizon that, even with clear skies, by the time the sky gets dark in the northwest, the comet is setting! And as the days and weeks pass, the progression of the starry background takes everything closer to the horizon — or you could think of the horizon rising, when looking at a chart. Add to that the fact that days are getting longer, sunset and twilight later, the comet lower… ugh! It seems everything’s a race! By mid-June Comet SWAN will be lost in bright twilight.
Comet C/2020 F8 (SWAN) was officially discovered March 25 of this year. It will make its closest approach to the Sun (perihelion) on May 27 when it will be 64 million kilometers from our star. Officially classified C/2020 F8 (SWAN) the new comet was first spotted by Australian amateur astronomer Michael Mattiazzo on April 11 using data from the Solar Wind ANisotropies (SWAN) instrument aboard the NASA/ESA Solar and Heliospheric Observatory (SOHO) recorded on March 25.
If you spot SWAN, please let us know! Good luck!
Comets, being temperamental beasts, don’t always act as we’d expect or hope. Most of the time comets gain brightness as they draw nearer the sun; Comet SWAN has been dimming! I’d seen earlier mentions but this Sky & Telescope article just came out today… HUMBUG!
May 20 — “Thousands of exoplanets have been identified so far, but little is known about how they form,” says Anthony Boccaletti who led the study from the Observatoire de Paris, PSL University, France. Astronomers know planets are born in dusty discs surrounding young stars, like AB Aurigae, as cold gas and dust clump together. The new observations with ESO’s VLT, published in Astronomy & Astrophysics, provide crucial clues to help scientists better understand this process.
“We need to observe very young systems to really capture the moment when planets form,” says Boccaletti. But until now astronomers had been unable to take sufficiently sharp and deep images of these young discs to find the ‘twist’ that marks the spot where a baby planet may be coming to existence.
The new images feature a stunning spiral of dust and gas around AB Aurigae, located 520 light-years away from Earth in the constellation of Auriga (The Charioteer). Spirals of this type signal the presence of baby planets, which ‘kick’ the gas, creating “disturbances in the disc in the form of a wave, somewhat like the wake of a boat on a lake,” explains Emmanuel Di Folco of the Astrophysics Laboratory of Bordeaux (LAB), France, who also participated in the study. As the planet rotates around the central star, this wave gets shaped into a spiral arm. The very bright yellow ‘twist’ region close to the center of the new AB Aurigae image, which lies at about the same distance from the star as Neptune from the Sun, is one of these disturbance sites where the team believe a planet is being made.
Observations of the AB Aurigae system made a few years ago with the Atacama Large Millimeter/submillimeter Array (ALMA), in which ESO is a partner, provided the first hints of ongoing planet formation around the star. In the ALMA images, scientists spotted two spiral arms of gas close to the star, lying within the disc’s inner region. Then, in 2019 and early 2020, Boccaletti and a team of astronomers from France, Taiwan, the US and Belgium set out to capture a clearer picture by turning the SPHERE instrument on ESO’s VLT in Chile toward the star. The SPHERE images are the deepest images of the AB Aurigae system obtained to date.
With SPHERE’s powerful imaging system, astronomers could see the fainter light from small dust grains and emissions coming from the inner disc. They confirmed the presence of the spiral arms first detected by ALMA and also spotted another remarkable feature, a ‘twist’, that points to the presence of ongoing planet formation in the disc. “The twist is expected from some theoretical models of planet formation,” says co-author Anne Dutrey, also at LAB. “It corresponds to the connection of two spirals — one winding inwards of the planet’s orbit, the other expanding outwards — which join at the planet location. They allow gas and dust from the disc to accrete onto the forming planet and make it grow.”
ESO is constructing the 39-meter Extremely Large Telescope, which will draw on the cutting-edge work of ALMA and SPHERE to study extrasolar worlds. As Boccaletti explains, this powerful telescope will allow astronomers to get even more detailed views of planets in the making. “We should be able to see directly and more precisely how the dynamics of the gas contributes to the formation of planets,” he concludes.
Back in 2007 astronomers were excited by a comet known as 17P/Holmes. What was so exciting was that the seemingly ordinary visitor from distant parts of the Solar System suddenly put on a great show. In October, the usually dim 17P/Holmes changed from an unremarkable telescopic object to become visible to the unaided eye, appearing as a yellow “star” in constellation Perseus. It was briefly the largest object in the Solar System. The outburst was believed to be similar to one that took place in 1892 making it visible to amateur astronomer Edwin Holmes, credited with its discovery on November 6 of that year. The reason for the sudden brightening or outbursts remains unknown.
I used my little Canon Rebel XT digital camera attached to the vintage Cooley Telescope at Stephens and attempted to capture images of the comet. The effort and the camera were pretty primitive compared with what we can do now but I got some images and they were the best I could manage at the time. Comet 17P/Holmes faded from visibility over the next several weeks. The somewhat odd appearance of the comet — no classic head and tail — is the result of our perspective: looking straight down its tail instead of from the side.
Recently I viewed a television show about comets and the strange behavior of 17P/Holmes was discussed. That program reminded me of the 2007 apparition and to look at my old images. There wasn’t much image data to work with but I reprocessed what I have and produced a new image a bit better than my first try; that image, shot through our old telescope, appears above.
The “P” in the comet’s designation stands for periodic, meaning after a period of time 17P will return to loop, once again, around Sun. In March 2014 (a seven-year period) the loop was made without an outburst. The next close approach to our Sun, perihelion, will take place on February 19, 2021. Will we be treated to another show?
— James Guilford
May 6 — A team of astronomers from the European Southern Observatory (ESO) and other institutes has discovered a black hole lying just 1,000 light-years from Earth. The black hole is closer to our Solar System than any other found to date and forms part of a triple system that can be seen with the naked eye. The team found evidence for the invisible object by tracking its two companion stars using the MPG/ESO 2.2-meter telescope at ESO’s La Silla Observatory in Chile. They say this system could just be the tip of the iceberg, as many more similar black holes could be found in the future.
“We were totally surprised when we realized that this is the first stellar system with a black hole that can be seen with the unaided eye,” says Petr Hadrava, Emeritus Scientist at the Academy of Sciences of the Czech Republic in Prague and co-author of the research. Located in the constellation of Telescopium, the system is so close to us that its stars can be viewed from the southern hemisphere on a dark, clear night without binoculars or a telescope. “This system contains the nearest black hole to Earth that we know of,” says ESO scientist Thomas Rivinius, who led the study published today in Astronomy & Astrophysics.
The team originally observed the system, called HR 6819, as part of a study of double-star systems. However, as they analyzed their observations, they were stunned when they revealed a third, previously undiscovered body in HR 6819: a black hole. The observations with the FEROS spectrograph on the MPG/ESO 2.2-meter telescope at La Silla showed that one of the two visible stars orbits an unseen object every 40 days, while the second star is at a large distance from this inner pair.
Dietrich Baade, Emeritus Astronomer at ESO in Garching and co-author of the study, says: “The observations needed to determine the period of 40 days had to be spread over several months. This was only possible thanks to ESO’s pioneering service-observing scheme under which observations are made by ESO staff on behalf of the scientists needing them.”
The hidden black hole in HR 6819 is one of the very first stellar-mass black holes found that do not interact violently with their environment and, therefore, appear truly black. But the team could spot its presence and calculate its mass by studying the orbit of the star in the inner pair. “An invisible object with a mass at least four times that of the Sun can only be a black hole,” concludes Rivinius, who is based in Chile.
Astronomers have spotted only a couple of dozen black holes in our galaxy to date, nearly all of which strongly interact with their environment and make their presence known by releasing powerful X-rays in this interaction. But scientists estimate that, over the Milky Way’s lifetime, many more stars collapsed into black holes as they ended their lives. The discovery of a silent, invisible black hole in HR 6819 provides clues about where the many hidden black holes in the Milky Way might be. “There must be hundreds of millions of black holes out there, but we know about only very few. Knowing what to look for should put us in a better position to find them,” says Rivinius. Baade adds that finding a black hole in a triple system so close by indicates that we are seeing just “the tip of an exciting iceberg.”
Already, astronomers believe their discovery could shine some light on a second system. “We realized that another system, called LB-1, may also be such a triple, though we’d need more observations to say for sure,” says Marianne Heida, a postdoctoral fellow at ESO and co-author of the paper. “LB-1 is a bit further away from Earth but still pretty close in astronomical terms, so that means that probably many more of these systems exist. By finding and studying them we can learn a lot about the formation and evolution of those rare stars that begin their lives with more than about 8 times the mass of the Sun and end them in a supernova explosion that leaves behind a black hole.”
The discoveries of these triple systems with an inner pair and a distant star could also provide clues about the violent cosmic mergers that release gravitational waves powerful enough to be detected on Earth. Some astronomers believe that the mergers can happen in systems with a similar configuration to HR 6819 or LB-1, but where the inner pair is made up of two black holes or of a black hole and a neutron star. The distant outer object can gravitationally impact the inner pair in such a way that it triggers a merger and the release of gravitational waves. Although HR 6819 and LB-1 have only one black hole and no neutron stars, these systems could help scientists understand how stellar collisions can happen in triple star systems.