Astronomers Measure a 1-billion Tesla Magnetic Field on the Surface of a Neutron Star

We recently observed the strongest magnetic field ever recorded in the Universe. The record-breaking field was discovered at the surface of a neutron star called GRO J1008-57 with a magnetic field strength of approximately 1 BILLION Tesla. For comparison, the Earth’s magnetic field clocks in at about 1/20,000 of a Tesla – tens of trillions of times weaker than you’d experience on this neutron star…and that is a good thing for your general health and wellbeing.

Neutron stars are the “dead cores” of once massive stars which have ended their lives as supernova. These stars exhausted their supply of hydrogen fuel in their core and a power balance between the internal energy of the star surging outward, and the star’s own massive gravity crushing inward, is cataclysmically unbalanced – gravity wins. The star collapses in on itself. The outer layers fall onto the core crushing it into the densest object we know of in the Universe – a neutron star. Even atoms are crushed. Negatively charged electrons are forced into the atomic nuclei meeting their positive proton counterparts creating more neutrons. When the core can be crushed no further, the outer remaining material of the star rebounds back into space in a massive explosion – a supernova. The resulting neutron star, made of the crushed stellar core, is so dense that a single sugar-cube-sized sampling would weigh billions of tons – as much as a mountain (though if you’re “worthy” you MIGHT able to lift it since Thor’s Hammer is made of the stuff). Neutron stars are typically about 20km in diameter and can still be a million degrees Kelvin at the surface.

But if they’re “dead,” how can neutron stars be some of the most magnetic and powerful objects in the Universe?

Composite image of the maelstrom at the heart of the Crab Nebula powered by a neutron star – Chandra X-Ray Observatory
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This is a Binary Star in the Process of Formation

About 460 light years away lies the Rho Ophiuchi cloud complex. It’s a molecular cloud—an active star-forming region—and it’s one of the closest ones. R. Ophiuchi is a dark nebula, a region so thick with dust that the visible light from stars is almost completely obscured.

But scientists working with ALMA have pin-pointed a pair of young proto-stars inside all that dust, doing the busy work of becoming active stars.

Continue reading “This is a Binary Star in the Process of Formation”

Much of the Lithium Here on Earth Came from Exploding White Dwarf Stars

The Big Bang produced the Universe’s hydrogen, helium, and a little lithium. Since then, it’s been up to stars (for the most part) to forge the rest of the elements, including the matter that you and I are made of. Stars are the nuclear forges responsible for creating most of the elements. But when it comes to lithium, there’s some uncertainty.

A new study shows where much of the lithium in our Solar System and our galaxy comes from: a type of stellar explosion called classical novae.

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Jupiter is so Big that our Solar System almost had two Suns

Europa and Io move across the face of Jupiter, with the Great Red Spot behind them. Image: NASA/JPL/Cassini, Kevin M. Gill

About half of all the star systems in the galaxy are made of pairs or triplets of stars. Our solar system features just one star, the Sun, and a host of (relatively) small planets. But it was almost not the case, and Jupiter got right on the edge of becoming the Sun’s smaller sibling.

Jupiter, the biggest planet in the solar system, is by far the largest. If you added up the masses of all the other planets, it wouldn’t even come to half of the mass of Jupiter. You could eliminate every single planet in the solar system except Jupiter, and you would basically still have…the solar system.

Continue reading “Jupiter is so Big that our Solar System almost had two Suns”

The Most Massive Neutron Star has been Found. It’s ALMOST the Most Massive Neutron Star That’s Even Possible

Neutron stars are the end-state of massive stars that have spent their fuel and exploded as supernovae. There’s an upper limit to their mass, because a massive enough star won’t become a neutron star; it’ll become a black hole. But finding that upper mass limit, or tipping point, between a star that becomes a black hole and one that becomes a neutron star, is something astronomers are still working on.

Now a new discovery from astronomers using the National Science Foundation’s (NSF) Green Bank Telescope (GBT) have found the most massive neutron star yet, putting some solid data in place about the so-called tipping point.

Continue reading “The Most Massive Neutron Star has been Found. It’s ALMOST the Most Massive Neutron Star That’s Even Possible”

There are Strange Objects Near the Center of the Galaxy. They Look Like Gas, but Behave Like Stars

During the 1970s, astronomer became aware of a massive radio source at the center of our galaxy that they later realized was a Supermassive Black Hole (SMBH) – which has since been named Sagittarius A*. And in a recent survey conducted by NASA’s Chandra X-ray Observatory, astronomers discovered evidence for hundreds or even thousands of black holes located in the same vicinity of the Milky Way.

But, as it turns out, the center of our galaxy has more mysteries that are just waiting to be discovered. For instance, a team of astronomers recently detected a number of “mystery objects” that appeared to be moving around the SMBH at Galactic Center. Using 12 years of data taken from the W.M. Keck Observatory in Hawaii, the astronomers found objects that looked like dust clouds but behaved like stars.

The research was conducted through a collaboration between Randy Campbell at the W.M. Keck Observatory, members of the Galactic Center Group at UCLA (Anna Ciurlo, Mark Morris, and Andrea Ghez) and Rainer Schoedel of the Instituto de Astrofisica de Andalucia (CSIC) in Granada, Spain. The results of this study were presented at the 232nd American Astronomical Society Meeting during a press conference titled “The Milky Way & Active Galactic Nuclei”.

Pictured here are members of GCOI in front of Keck Observatory on Maunakea, Hawaii, during a visit last year. Credit: W.M. Keck Observatory

As Ciurlo explained in a recent W.M. Keck press release:

“These compact dusty stellar objects move extremely fast and close to our Galaxy’s supermassive black hole. It is fascinating to watch them move from year to year. How did they get there? And what will they become? They must have an interesting story to tell.”

The researchers made their discovery using 12 years of spectroscopic measurements obtained by the Keck Observatory’s OH-Suppressing Infrared Imaging Spectrograph (OSIRIS). These objects – which were designed as G3, G4, and G5 – were found while examining the gas dynamics of the center of our galaxy, and were distinguished from background emissions because of their movements.

“We started this project thinking that if we looked carefully at the complicated structure of gas and dust near the supermassive black hole, we might detect some subtle changes to the shape and velocity,” explained Randy Campbell. “It was quite surprising to detect several objects that have very distinct movement and characteristics that place them in the G-object class, or dusty stellar objects.”

Astronomers first discovered G-objects in proximity to Sagittarius A* more than a decade ago – G1 was discovered in 2004 and G2 in 2012. Initially, both were thought to be gas clouds until they made their closest approach to the supermassive black hole and survived. Ordinarily, the SMBHs gravitational pull would shred gas clouds apart, but this did not happen with G1 and G2.

3-D spectro-imaging data cube produced using software called OSIRIS-Volume Display ( OsrsVol) to separate G3, G4, and G5 from the background emission. Credit: W.M. Keck Observatory

Because these newly discovered infrared sources (G3, G4, and G5) shared the physical characteristics of G1 and G2, the team concluded that they could potentially be G-objects. What makes G-objects unusual is their “puffiness”, where they appear to be cloaked in a layer of dust and gas that makes them difficult to detect. Unlike other stars, astronomers only see a glowing envelope of dust when looking at G-objects.

To see these objects clearly through their obscuring envelope of dust and gas, Campbell developed a tool called the OSIRIS-Volume Display (OsrsVol). As Campbell described it:

“OsrsVol allowed us to isolate these G-objects from the background emission and analyze the spectral data in three dimensions: two spatial dimensions, and the wavelength dimension that provides velocity information. Once we were able to distinguish the objects in a 3-D data cube, we could then track their motion over time relative to the black hole.”

UCLA Astronomy Professor Mark Morris, a co-principal investigator and fellow member of UCLA’s Galactic Center Orbits Initiative (GCOI), was also involved in the study. As he indicated:

“If they were gas clouds, G1 and G2 would not have been able to stay intact. Our view of the G-objects is that they are bloated stars – stars that have become so large that the tidal forces exerted by the central black hole can pull matter off of their stellar atmospheres when the stars get close enough, but have a stellar core with enough mass to remain intact. The question is then, why are they so large?

Chandra data (above, graph) on J0806 show that its X-rays vary with a period of 321.5 seconds, or slightly more than five minutes. This implies that the X-ray source is a binary star system where two white dwarf stars are orbiting each other (above, illustration) only 50,000 miles apart, making it one of the smallest known binary orbits in the Galaxy. According to Einstein's General Theory of Relativity, such a system should produce gravitational waves - ripples in space-time - that carry energy away from the system and cause the stars to move closer together. X-ray and optical observations indicate that the orbital period of this system is decreasing by 1.2 milliseconds every year, which means that the stars are moving closer at a rate of 2 feet per year.
A binary star system potentially on the verge of a stellar collision. Credit: Chandra

After examining the objects, the team noticed that there was a great deal of energy was emanating from them, more than what would be expected from typical stars. As a result, they theorized that these G-objects are the result of stellar mergers, which occur when two stars that orbit each other (aka. binaries) crash into each other. This would have been caused by the long-term gravitational influence of the SMBH.

The resulting single object would be distended (i.e. swell up) over the course of millions of years before it finally settled down and appeared like a normal-sized star. The combined objects that resulted from these violent mergers could explain where the excess energy came from and why they behave like stars do. As Andrea Ghez, the founder and director of GCOI, explained:

“This is what I find most exciting. If these objects are indeed binary star systems that have been driven to merge through their interaction with the central supermassive black hole, this may provide us with insight into a process which may be responsible for the recently discovered stellar mass black hole mergers that have been detected through gravitational waves.”

Looking ahead, the team plans to continue following the size and shape of the G-objects’ orbits in the hopes of determining how they formed. They will be paying especially close attention when these stellar objects make their closest approach to Sagittarius A*, since this will allow them to further observe their behavior and see if they remain intact (as G1 and G2 did).

This will take a few decades, with G3 making its closest pass in 20 years and G4 and G5 taking decades longer. In the meantime, the team hopes to learn more about these “puffy” star-like objects by following their dynamical evolution using Keck’s OSIRIS instrument. As Ciurlo stated:

“Understanding G-objects can teach us a lot about the Galactic Center’s fascinating and still mysterious environment. There are so many things going on that every localized process can help explain how this extreme, exotic environment works.”

And be sure to check out this video of the presentation, which takes place from 18:30 until 30:20:

Further Reading: Keck Observatory

Weekly Space Hangout – February 3, 2017: Meredith Rawls & the LSST

Host: Fraser Cain (@fcain)

Special Guest: Meredith Rawls

Meredith is a Postdoctoral Researcher in the Department of Astronomy at the University of Washington. She writes software to prepare for the coming onslaught of data from the Large Synoptic Survey Telescope and studies weird binary stars. She is also the lead organizer of the ComSciCon-Pacific Northwest workshop for STEM graduate students in Seattle this March. Meredith holds degrees in physics and astronomy from Harvey Mudd College, San Diego State University, and New Mexico State University. When she’s not science-ing or telling people all about it, she plays viola, volunteers at summer camp, and advocates for more equity and less light pollution.


Paul M. Sutter ( / @PaulMattSutter)
Kimberly Cartier ( / @AstroKimCartier )

Their stories this week:
Oxygen on the moon

Nearby “super-void” shapes galaxy motion

First science from Keck’s vortex coronograph

We use a tool called Trello to submit and vote on stories we would like to see covered each week, and then Fraser will be selecting the stories from there. Here is the link to the Trello WSH page (, which you can see without logging in. If you’d like to vote, just create a login and help us decide what to cover!

If you would like to join the Weekly Space Hangout Crew, visit their site here and sign up. They’re a great team who can help you join our online discussions!

If you would like to sign up for the AstronomyCast Solar Eclipse Escape, where you can meet Fraser and Pamela, plus WSH Crew and other fans, visit our site linked above and sign up!

We record the Weekly Space Hangout every Friday at 12:00 pm Pacific / 3:00 pm Eastern. You can watch us live on Universe Today, or the Universe Today YouTube page

A Moon With Two Suns: Making Art from Science

A view of Kepler 47c and binary stars. ©Digital Drew. All rights reserved.

What would it look like on a hypothetical icy moon orbiting the exoplanet Kepler 47c? Perhaps something like this.

This is an illustration by an artist who goes by the name Digital Drew on Flickr. Drew creates landscapes of imagined alien worlds orbiting stars (and sometimes planets) that actually exist in the Universe. With 3D software, a little science and a lot of imagination, Drew shows us what skies might look like on other planets.

Kepler 47c (KOI-3154.02) is a Neptune-sized exoplanet orbiting a binary star pair 4,600 light-years away. It is part of the first circumbinary system ever discovered — one of at least two planets orbiting a pair of stars. In the image here, Kepler 47c is seen at upper left.

681737main_K47system_diagram_4x3_946-710What makes this exoplanet so exciting is that it is within the habitable zone around the stellar pair. So even though the planet itself may be a gas giant and thus not particularly suitable for life, any moons it has in orbit just might be.

While its slightly smaller planetary companion Kepler 47b orbits much too closely to the twin suns for water to exist as a liquid, 47c’s orbit is much farther out, completing one revolution every 303 days. Mainly illuminated by a star like our Sun but about 15% dimmer, this is a region where you could very well find a large rocky moon with conditions similar to Earth’s.

Fly a spacecraft over its higher elevations and you just might see a scene like this, a double sunset over a glacier-filled valley with a crescent gas giant dominating the sky. (Makes one wonder what the balmier regions might look like!)

“Unlike our sun, many stars are part of multiple-star systems where two or more stars orbit one another. The question always has been — do they have planets and planetary systems? This Kepler discovery proves that they do. In our search for habitable planets, we have found more opportunities for life to exist.”

– William Borucki, Kepler mission principal investigator (Sept. 2012)

And as more giant planets are discovered within their system’s habitable zones, the more there’s a chance that habitable moons could exist — or perhaps even be more common than habitable planets! Just recently the citizen science project Planet Hunters announced the potential exoplanet PH2 b, a Jupiter-sized world that orbits within a habitable zone. In our Solar System Jupiter has lots of moons; PH2 b could very well have a large number of moons of its own, any number of them with liquid water on their surfaces and temperatures “just right” for life.

Read more: Exciting Potential for Habitable Exomoons

While it will likely be quite some time before we see any direct observations of an actual exomoon, and possibly never from one, we must rely on the work of artists like Digital Drew to illustrate the many possibilities that exist.

See more of Drew’s work on his Flickr page here, and read more about the discovery of the Kepler 47 system here.

Inset image: Diagram of the Kepler 47 system compared to the inner Solar System. Credit: NASA/JPL-Caltech/T. Pyle.

Weekly SkyWatcher’s Forecast: June 18-24, 2012

Greetings, fellow SkyWatchers! Let’s begin the week with some awesome galactic studies and enjoy a meteor shower during Summer Solstice! We’ll be studying variable stars, the planet Mars, Saturn, the Moon and Mercury, too! There’s always a bit of astronomy history and some unusual things to learn about. When you’re ready, just meet me in the back yard…

Monday, June 18 – With dark skies on our side, we’ll spend the next few days concentrating on a very specific region of the night sky. Legend tells us the constellation of Crater is the cup of the gods – cup befitting the god of the skies, Apollo. Who holds this cup, dressed in black? It’s the Raven, Corvus. The tale is a sad one – a story of a creature sent to fetch water for his master, only to tarry too long waiting on a fig to ripen. When he realized his mistake, the sorry Raven returned to Apollo with his cup and brought along the serpent Hydra in his claws as well. Angry, Apollo tossed them into the sky for all eternity and it is in the south they stay until this day.

For the next few days, it will be our pleasure to study the Cup and the Raven. The galaxies I have chosen are done particularly for those of us who still star hop. I will start with a “marker” star that should be easily visible unaided on a night capable of supporting this kind of study. The field stars are quite recognizable in the finder and this is an area that takes some work. Because these galaxies approach magnitude 13, they are best suited to the larger telescope.

Now, let’s go between map and sky and identify both Zeta and Eta Crater and form a triangle. Our mark is directly south of Eta the same distance as between the two stars. At low power, the 12.7 magnitude NGC 3981 (Right Ascension: 11 : 56.1 – Declination: -19 : 54) sits inside a stretched triangle of stars. Upon magnification, an elongated, near edge-on spiral structure with a bright nucleus appears. Patience and aversion makes this “stand up” galaxy appear to have a vague fading at the frontiers with faint extensions. A moment of clarity is all it takes to see tiny star caught at the edge.

Tuesday, June 19 – New Moon! Tonight’s first study object, 12.7 magnitude NGC 3956 (Right Ascension: 11 : 54.0 – Declination: -20 : 34) is about a degree due south of NGC 3981. When first viewed, it appears as edge-on structure at low power. Upon study it takes on the form of a highly inclined spiral. A beautiful multiple star, and a difficult double star also resides with the NGC 3956 – appearing almost to triangulate with it. Aversion brings up a very bright core region which over the course of time and study appears to extend away from the center, giving this very sweet galaxy more structure than can be called from it with one observation.

Our next target is a little more than two degrees further south of our last study. The 12.8 magnitude NGC 3955 (Right Ascension: 11 : 54.0 – Declination: -23 : 10) is a very even, elongated spiral structure requiring a minimum of aversion once the mind and eye “see” its position. Not particularly an impressive galaxy, the NGC 3955 does, however, have a star caught at the edge as well. After several viewings, the best structure I can pull from this one is a slight concentration toward the core.

Now we’ll study an interacting pair and all that is required is that you find 31 Corvii, an unaided eye star west of Gamma and Epsilon Corvii. Now we’re ready to nudge the scope about one degree north. The 11th magnitude NGC 4038/39 (Right Ascension: 12 : 01.9 – Declination: -18 : 52) is a tight, but superior pair of interacting galaxies. Often referred to as either the “Ringtail” or the “Antenna”, this pair deeply captured the public’s imagination when photographed by the Hubble. (Unfortunately, we don’t have the Hubble, but what we have is set of optics and the patience to find them.) At low power the pair presents two very stellar core regions surrounded by a curiously shaped nebulosity. Now, drop the power on it and practice patience – because it’s worth it! When that perfect moment of clarity arrives, we have crackling structure. Unusual, clumpy, odd arms appear at strong aversion. Behind all this is a galactic “sheen” that hints at all the beauty seen in the Hubble photographs. It’s a tight little fellow, but worth every moment it takes to find it.

Return to 31 Corvii and head one half degree northwest to discover 11.6 magnitude NGC 4027 (Right Ascension: 11 : 59.5 – Declination: -19 : 16). Relatively large, and faint at low power, this one also deserves both magnification and attention. Why? Because it rocks! It has a wonderful coma shape with a single, unmistakable bold arm. The bright nucleus seems to almost curl along with this arm shape and during aversion a single stellar point appears at its tip. This one is a real treat!

Wednesday, June 20 – Today marks the official date of 2012 Summer Solstice!

With no Moon to contend with in the predawn hours, we welcome the “shooting stars” as we pass through another portion of the Ophiuchid meteor stream. The radiant for this pass will be nearer Sagittarius and the fall rate varies from 8 to 20, but it can sometimes produce unexpectedly more.

Tonight let’s look to the sky again and fixate on Eta Crater – our study lay one half degree southeast. The 12.8 magnitude NGC 4033 (Right Ascension: 12 : 00.6 – Declination: -17 : 51) is a tough call even for a large scope. Appearing elliptical at low power, it does take on some stretch at magnification. It is smallish, even and quite unremarkable. It requires good aversion and a bit of patience to find. Good luck!

The last of our studies resides by a star, one degree west of Beta Corvii. In order to “see” anything even remotely called structure in NGC 4462 (Right Ascension: 12 : 29.3 – Declination: -23 : 10), this one is a high power only galaxy that is best when the accompanying star is kept out of the field as much as possible. It holds a definite stellar nucleus and a concentration that pulls away from it making it almost appear barred. On an exceptional night with a large scope, wide aversion and moments of clarity show what may be three to four glints inside the structure. Ultra tiny pinholes in another universe? Or perhaps an unimaginably huge, bright globular clusters? While attention is focused on trying to draw out these points, you’ll notice this galaxy’s structure much more clearly. Another true beauty and fitting way to end this particular study field!

Thursday, June 21 – Keep an eye out for the exiting planet Mars! It’s been on the move and has now crossed the border of Virgo and returned to Leo. Have you noticed it quickly changing in both apparent brightness and size? It won’t be long until it’s gone! And speaking of planets on the move, have you spotted Mercury yet? You can find the swift little planet low on the western horizon just after sunset. Look for it just to the south of Castor and Pollux!

For challenging larger telescope studies, return to eastern edge of Mare Crisium and Promontorium Agarum to identify shallow crater Condorcet to its east. Look along the shore of the mare for a mountain to the south known as Mons Usov. Just to its north Luna 24 landed and directly to its west are the remains of Luna 15. We’ll study more about them in the future. Can you spot the tiny dark well of crater Fahrenheit nearby? Continue with your telescope north of Mare Crisium for even more challenging features such as northeast limb studies Mare Smythii and Mare Marginis. Between them you will see the long oval crater Jansky – bordered by Jansky A at the very outer edge.

While you’re out tonight, take a look at the skies for a circlet of seven stars that reside about halfway between orange Arcturus and brilliant blue/white Vega. This quiet constellation is named Corona Borealis – or the “Northern Crown.” Just northwest of its brightest star is a huge concentration of over 400 galaxies that reside over a billion light-years away from us. This area is so small from our point of view that we could cover it with our thumbnail held at arm’s length!

For variable star fans, let’s explore Corona Borealis and focus our attention on S – located just west of Theta – the westernmost star in the constellation’s arc formation. At magnitude 5.3, this long-term variable takes almost a year to go through its changes; usually far outshining the 7th magnitude star to its northeast – but will drop to a barely visible magnitude 14 at minimum. Compare it to the eclipsing binary U Coronae Borealis about a degree northwest. In slightly over three days this Algol-type will range by a full magnitude as its companions draw together.

Friday, June 22 – Today celebrates the founding of the Royal Greenwich Observatory in 1675. That’s 332 years of astronomy! Also on this date in history, in 1978, James Christy of the US Naval Observatory in Flagstaff Arizona discovered Pluto’s satellite Charon.

If you’d like to practice some unaided eye astronomy, then look no further than the western skyline as the Sun sets. At twilight you’ll first notice the very slender crescent Moon – but don’t delay your observations as you can spot Mercury to the west! The inner planet will set very fast, so you’ll need an open horizon. But that’s not all… the speedy little dude is lined up perfectly with Castor and Pollux! With the foursome nearly “in a row” this will make a very cool apparition to remind friends and family to watch for!

Now, grab your favorite optics for a selenographic treat tonight return to the area just north of Mare Crisium area to observe spectacular crater Cleomides. This two million year old crater is separated from Crisium by some 60 kilometers of mountainous terrain. Telescopically, Cleomides is a true delight at high power. To Cleomides’ east, begin by identifying Delmotte, and to the northwest, Trailes and Debes. About twice Clemoides’ width northwest, you will see a sharply well-defined Class I crater Geminus. Named for the Greek astronomer and mathematician Geminos, this 86 kilometer wide crater shows a smooth floor and displays a long, low dune across its middle.

When you’re finished, point your binoculars or telescopes back towards Corona Borealis and about three fingerwidths northwest of Alpha for variable star R (Ra 15. 48.6 Dec +28 09). This star is a total enigma. Discovered in 1795, most of the time R carries a magnitude near 6, but can drop to magnitude 14 in a matter of weeks – only to unexpectedly brighten again! It is believed that R emits a carbon cloud which blocks its light. When studied at minima, the light curve resembles a “reverse nova,” and has a peculiar spectrum. It is very possible this ancient Population II star has used all of its hydrogen fuel and is now fusing helium to carbon. It’s so odd that science can’t even directly determine its distance!

Saturday, June 23 – If you missed yesterday’s apparition of Mercury, then try again tonight. While the small planet might be dim, just look for the brighter pairing of Castor and Pollux above the western horizon at twilight. Can’t find it? Then try this. When you look at this famous pair of stars, judge the distance between the two. Now, apply that same distance and angle to the left (southern) star, Pollux, and you’ve found Mercury! Need more? Then check out the Moon and you’ll see Regulus is about a fistwidth to the east/southeast and Mars is a little more than two handspans to the southeast. Still more? Then continue on from Mars southeast about about another two handspans and you’ll see the pairing of Spica and Saturn!

Using your telescope tonight on the Moon will call up previous study craters, Atlas and Hercules to the lunar north. If you walk along the terminator to the due west of Atlas and Hercules, you’ll see the punctuation of 40 kilometer wide Burg just emerging from the shadows. While it doesn’t appear to be a grand crater just yet, it has a redeeming feature – it’s deep – real deep. If Burg were filled with water here on Earth, it would require a deep submergence vehicle like ALVIN to reach its 3680 meter floor! This class II crater stands nearly alone on an expanse of lunarscape known as Lacus Mortis. If the terminator has advanced enough at your time of viewing, you may be able to see this walled-plain’s western boundary peeking out of the shadows.

While we’re out, let’s have a look at Delta Serpens. To the eye and binoculars, 4th magnitude Delta is a widely separated visual double star… But power up in the telescope to have a look at a wonderfully difficult binary. Divided by no more than 4 arc seconds, 210 light-year distant Delta and its 5th magnitude companion could be as old as 800 million years and on the verge of becoming evolved giants. Separated by about 9 times the distance of Pluto from our Sun, the white primary is a Delta Scuti-type variable which changes subtly in less than four hours. Although it takes the pair 3200 years to orbit each other, you’ll find Delta Serpens to be an excellent challenge for your optics.

Sunday, June 24 – On this day in 1881, Sir William Huggins made the first photographic spectrum of a comet (1881 III) and discovered cyanogen (CN) emission at violet wavelengths. Unfortunately, his discovery caused public panic around 29 years later when Earth passed through the tail of Halley’s Comet. What a shame the public didn’t realize that cyanogens are also released organically! More than fearing what is in a comet’s tail, they should have been thinking about what might happen should a comet strike. Tonight look at the wasted Southern Highland area of the Moon with new eyes… Many of these craters you see were caused by impacts – some as large as the nucleus of Halley itself.

Now let’s pick up a binocular curiosity located on the northeast shore of Mare Serenitatis. Re-identify the bright ring of Posidonius, which contains several equally bright points both around and within it – and look at Mare Crisium and get a feel for its size. A little more than one Crisium’s length west of Posidonius you’ll meet Aristotle and Eudoxus. Drop a similar length south and you will be at the tiny, bright crater Linne on the expanse of Mare Serenitatis. So what’s so cool about this little white dot? With only binoculars you are resolving a crater that is one mile wide, in a seven mile wide patch of bright ejecta – from close to 400,000 kilometers away! While you were there, did you notice how much Proclus has changed tonight? It is now a bright circle and beginning to show bright lunar rays…

Before we head for deep sky, be sure to at least take a look at Saturn and Mars. Right now the Ring King has reached its greatest westward position and will begin its tour back to the east. Now, check out Mars’ position to the west and measure with your hands roughly how far apart they are. At this point they are separated by about two handspans. Check again in a few weeks to see planetary motion displayed right before your eyes!

Now let’s turn binoculars or telescopes towards magnitude 2.7 Alpha Librae – the second brightest star in the celestial “Scales.” Its proper name is Zuben El Genubi, and even as “Star Wars” as that sounds, the “Southern Claw” is actually quite close to home at a distance of only 65 light-years. No matter what size optics you are using, you’ll easily see Alpha’s 5th magnitude companion widely spaced and sharing the same proper motion. Alpha itself is a spectroscopic binary which was verified during an occultation event, and its inseparable companion is only a half magnitude dimmer according to the light curves. Enjoy this easy pair tonight!

Until next week? Ask for the Moon… But keep on reaching for the stars!