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Monday, August 27, 2018

The Great American Eclipse Remembered

Note: This is the article I should have written one year ago, so now it has become a chance to revisit the past as we so often do on anniversaries. So let us take a look back on August 21, 2017...

“The Great American Eclipse” of August 21, 2017, started its journey across the continental US on the Oregon coast, crossing the town of Corvallis (home of my brother and his wife) about 50 miles inland; this was to be our spot for viewing the eclipse as it dovetailed nicely with our vacation plans to visit them in the summer.

My first thought was to bring a small telescope and capture the eclipse close up, but soon realized that I didn’t want to get hung up on all the work and equipment needed - I've seen many different eclipse photos over the years and I didn't feel like duplicating what has been done before. I was more interested in just experiencing the eclipse as it happened via the naked eye, as well as everything around me - something you can't capture from close up pictures of the event. I settled on using a simple GoPro camera (which has a wide-angle perspective) and recording a video of the eclipse starting about 20 minutes before totality and ending 20 minutes after, right from my brother's backyard. What we have below is a short excerpt from that video around totality:

August 21, 2017 Total Solar Eclipse from Corvallis, Oregon

Although nothing can really replicate 100% of our eclipse experience, I think this video successfully captures some the feeling of what it was like during the eclipse - it was truly (for a lack of a better description) "awe-inspiring", definitely the best astronomical event I have seen in my lifetime. If you never have seen one "in person" it is highly recommended.
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Friday, August 17, 2018

The Solar System In a Night-Shell

Recently, you may have noticed an extra one or two very bright stars in the sky, just after sunset. That’s because we’re currently experiencing a rather special celestial treat: a relatively rare positioning of all eight planets (and, three minor planets!) into just a bit more than one side of the sky - at nearly the same time! Alignments like this aren’t exactly common, so, go outside and take a look - while it’s still not too late! (This celestial configuration will begin to deteriorate over the coming weeks).

Starting at sunset, in their order of appearance, relative to their apparent distance from the sun, and just to the west of the sun, is Mercury, first planet out from the sun, which is now so close to our star, from our perspective, that it’s easily lost in the glare and a bit hard on the eyes for that reason, without a telescope, but it’s there -  just about 6 degrees to the southwest, at stellar magnitude +.60.**

The Solar System In a Night-shell

Believe it or not, next up - we’re already at the outer reaches of the Solar system - minor, or dwarf planet, Pluto! But that’s because of its position against the sky, in the relative background, as compared to the other, and much closer planets. For now - just know that it’s there, about 15 degrees to the east of Saturn. It bottoms out at a dim +14.4 magnitude, accessible only in a moderate to the large-sized telescope.

Next, moving, now, East of the sun is a dwarf planet, Ceres. You’ll need a small telescope to spot it. Ceres was discovered, telescopically, in 1801 and at that time, it was realized that Ceres was much closer to Earth than were the stars - but smaller than any planet; therefore, it was cataloged as an asteroid. And, it kept that label, until relatively recent years when it was re-labelled a minor planet. Under that heading is the sub-heading of, ‘dwarf planet’, and that’s where Ceres currently resides, "taxonomically", anyway. The reasons for the changes to Ceres, 4 Vesta, and Pluto as dwarf planets are entirely logical and valid; you’ll have to take my word for that. You’ll find Ceres if you dare - and, if you have a medium-sized telescope - between the sun and Venus, at a dim, +8.8 magnitude.

Now, on our way to Venus. Venus, the second planet from the sun - is the brightest thing in the sky (sans the moon and sun). Seemingly hanging there, low in the west, Venus shines its stunning, white brilliance down on us - at a staggering magnitude -4.4, and at about 12 degrees east of the sun. If you miss it - well, you’re just not paying attention!

Now - look down at the ground by your feet. There sits Earth, third planet from the sun. If you were to see yourself standing there, from the perspective of the orbiting, International Space Station, you’d first note that you were standing, nearby some dividing line - the line delineating light from the darkness: the terminator, dividing night from day. You are just about, literally, to enter and cross into, the "Twilight Zone"! (Now, how many people can say that they’ve, knowingly, done that - hmmm?!) And this is a good thing because it represents the progression of time, and the rotation of Earth on its axis and, thereby, rolling you - or, perhaps, dragging you - into the deep, dark night. But this is an even better thing because the passage of the early evening hours will bring, up into the sky, from over the eastern horizon, three of our Solar system's showpieces; Jupiter, Saturn, and Mars.

First, sitting, watchfully - almost “king-like” - and due South, at an elevation of around 30 degrees, is His Deified Majesty, Jove - also known by the Romans, as Jupiter. With just about any pair of binoculars, you’ll get to see four of, giant Jupiter’s, giant moons - Callisto, Europa, Ganymede, and Io - that is, unless one or two of them happen to be in Jupiter’s shadow at the time of your observation. But don’t worry; they don’t stay in shadow behind the planet long! With a telescope, you may also see some, very pastel, cloud bands, near the planet’s equatorial region. Jupiter is now, the third brightest light, in the sky, at a bright, white-ish, magnitude -2.70.

Have you ever seen ‘rings’ around any celestial object before?; I mean, for yourself - with your very own eyes?! Probably, you haven’t - so now’s your chance! - that is if you happen to have access to, at least, a small telescope, or high-powered binoculars.

If not, don’t worry about it; you still cannot help but notice Saturn, anyway, because it’s now such a  bright, yellowish-white, at an apparent magnitude of +.70: one of the very brightest lights currently in the sky, best seen around 9:00PM. But in a telescope, you will make out Saturn’s ring system, currently lying at an oblique angle to its plane of rotation, so that they will appear to be, almost, “wide-open” at this time around the planet - and that is a wonderful, and rare thing, indeed; Saturn’s rings go through long cycles of appearing open or closed, from our perspective, about every 27 years! Right now they are “wide-open” - you may never get to see this, again…

After Saturn is another object out there, just worth noting, and going unseen without a telescope: dwarf planet, and former asteroid, 4 Vesta. It’s feeble light, just creeps through our atmosphere at a dismal +6.4 magnitude, well beyond the abilities of the average, the human eye.

Now, comes Mars. Make sure you identify this small-ish, ruddy world for long-term memory: Mars is closer to Earth than it has been in 157 years! Though the red planet closes in on Earth every two years, due to the proximity of the orbits of both planets, there is another component to the Martian orbits’, slightly elongated shape which brings it even closer, periodically. This happens when the point in its orbit that lies closest to the sun, is in sync with the Earth’s position - and that is right about now!

Mars is currently experiencing one of the relatively rare, long-duration, global sandstorms that it's known for. The raging storm has been going on, for about 3 months now. I saw Mars through the telescope about two weeks ago, at high magnification. Though the planet, normally, has a variety of surface features to offer the observer, in the form of dark grey patches, volcanic calderas, white polar caps, and such, it now presents a uniform, planet-wide rust color, as atmospheric particulates from the dust storm circulate around its small, thin blanket of air. However - Mars is the second brightest thing in the sky, right now, after Venus - looking more like a reddish "blob", hanging in the air, toward the South than it does a star or a planet. There is a distinct perception of a disk to this orb, due to its slightly larger angular size in the sky, than that of the other planets and that, due to its current proximity to Earth. Mars is now glowing, distinctly reddish, at magnitude -2.6, rising at around 8:30PM and well placed for viewing, high up in the sky, by 11:00PM. It’s worth the view, with or without a telescope or binoculars!

And, nearly last, but not, nearly least - by any stretch - are Uranus and Neptune - the seventh and eighth planets of our Solar system - far beyond the reach of the unaided eye, but within telescopic range. They are nearby each other, well into the small hours, at around 30 degrees and 60 degrees, east, of Mars, and +5.7 and +7.8 magnitudes, respectively.

Which leaves our own, familiar moon, Luna, now (at the time of this writing), as a dainty, waxing crescent, sitting just above Venus, but moving progressively toward the east, as the nights of the month wear on. And, there you have It - our entire Solar system, in a “night”-shell (well, you just know I couldn’t resist that one!)

** The system used by astronomers to denote the relative, apparent brightnesses in celestial objects, is the Stellar Magnitude Scale. Beginning at 0, the scale uses both positive and negative numbers: those in the minus range, being brighter than those in the plus range. Though it's called the ‘stellar’ magnitude scale, it is used to mark the brightnesses of all celestial objects; stars, planets, comets, and asteroids included. On that note, the consistently, brightest point of light that can be seen from the Earth, is the star, Sirius, in the constellation Canis Major (the 'Big Dog'). It is given the negative magnitude number, -1.4. The planet Venus, currently, is at magnitude -4.3 - several times brighter than Sirius - but Venus’ albedo varies over time, and,  although Venus is the brightest object in the sky, after the sun and moon - it is a planet.  On the plus side of the scale, the human eye can see stars down to about, a fairly dim, magnitude +6, on a very dark, clear night. And so, the answer to the oft-asked question: “What is the brightest star in the night sky?”, is, technically, the star Sirius, at magnitude -1.4.
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Thursday, August 2, 2018

What's In the Sky - August 2018

Warm summer nights seem like they're tailor-made for backyard astronomers. Evenings throughout August are great opportunities to get the whole family outside for summer stargazing fun with a telescope or your favorite pair of binoculars. Here are a few of Orion's top picks for August stargazing:

New Moon 

The new moon is the morning of August 12th (2:30am), so the nights of August 10th into the 11th and the 11th into the 12th will be the darkest nights of the month and therefore the best time to observe the more faint objects like galaxies and star clusters. Grab your gear and enjoy!

Meteor (Perseid's) and M45 (Pleiades) - Imaged by Mark Bell on 08/10/2013 using an   Orion StarShoot All-In-One Astrophotography Camera.
Meteor (Perseid's) and M45 (Pleiades) - Imaged by Mark Bell on 08/10/2013 using an 
Orion StarShoot All-In-One Astrophotography Camera.

Perseids meteor shower

Two great nights to enjoy Perseid watching! Go outside on the evening of August 11th and/or after midnight on August 12th for the best chances to see the peak of the Perseids meteor shower. With up to 60 meteors expected per hour, this is one of the most popular meteor showers of the year. Conditions will be excellent this year since the thin crescent Moon will set early on the 12th, providing dark skies.

Venus at Greatest Eastern Elongation

After sunset on August 17th, the bright planet Venus will be at its greatest eastern elongation, reaching its highest point in the sky. Look above the western horizon right after the Sun sets to catch a glimpse of our next-door neighbor planet in a telescope.


Many excellent examples of gaseous nebulas are on display in the skies of August. The brightest are M16 the Eagle Nebula, M17 the Swan Nebula, M20 the Trifid Nebula and the very bright M8, Lagoon Nebula. All are visible in binoculars from dark locations with good seeing. Use a small to moderate aperture telescope with the aid of an Oxygen-III eyepiece filter or Broadband SkyGlow Filter to see these nebulas from locations plagued by light pollution.

August Challenge Object

Our challenge this month is a surprisingly easy object to see with a telescope, but not so easy with binoculars. Look for M27, the Dumbbell Nebula in the constellation of Vulpecula, just south of Cygnus. M27 is one of the nearest and brightest planetary nebulas visible from Earth. It's so big that it can be spotted in humble 7 x 50 binoculars, but it does present a challenge! Try to track M27 down this August with your binoculars; it will be a small dot, slightly larger than the surrounding stars, but definitely visible through 50mm or larger binoculars.

All objects described above can easily be seen with the suggested equipment from a dark sky site, a viewing location some distance away from city lights where light pollution and when bright moonlight does not overpower the stars.
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Wednesday, August 1, 2018

Home Is Where the Converged Galactic Core Is

Arcturus is the bright, reddish star which can be seen during the summer months, currently, at an altitude of about 40° (or, about 4 fist-widths) from the western horizon at sunset, and from about sunset until around 2:00am, when it sets below the western horizon.

Arcturus is the brightest star in the constellation, Bootes - the 'herdsman'; the brightest star in the northern celestial hemisphere, and the fourth brightest star in the skies of Earth. Its name comes from the ancient Greek, meaning, "Guardian of the Bear"; Arcturus appears to be trailing the constellations, Ursa Major and Ursa Minor (the 'Great Bear', and the 'Little Bear', respectively). It can easily be located by following the arc of the handle of the Big Dipper, just out into the nearby, celestial blackness - just remember: "Arc, to Arcturus"; and, there Arcturus sits, alone.

Two Small Galaxies Collide to Form Our Milky Way Galaxy

This 'red-giant' star, is about the same mass as our Sun, but it is nearly 200 times more luminous. This is because of its enormous size, with a diameter of 22,000,000 miles. Our Sun, "Sol", currently, has an average diameter of 864,000 miles, making Arcturus nearly 26 times the size of the sun, but - it is also 217,000,000,000,000 (217 trillion) miles from Earth, or about 37 light-years distant, accounting for its apparent, relative diminution to our sun. Arcturus is near twice as old as our Sol, at around 7.1 billion years.

Red giant stars are stars that are in the later stages of stellar evolution: briefly, they have exhausted their supply of the fuel that sustains them at their cores - Hydrogen. They are still consuming the remaining H in their outermost, gaseous shells by thermonuclear fusion, but have lost so much of their original mass that their surface temperature drops, significantly, and they become so, "swollen", that their remaining 'bulk' is gradually extended into the surrounding space. One day, about 4.5 billion years from now, our own Sun, currently a yellow-dwarf star on the Main Sequence Diagram of Stellar Evolution (also called the Hertzprung-Russell Diagram), will begin its final journey through the red giant phase, as its own nuclear furnace starts to cool down, to begin the journey to its final state - a tiny, hot star, known as a white dwarf.

Though Arcturus is 37 light-years away from our Solar system, its relatively feeble light output was used as a switch, to turn on the lights at the Chicago World's Fair, in 1933, by converting that radiation, using a photoelectric-effect process, combined with a telescope, into electrical signals and, thereby, 'tripping the switch' that turned on the lights at that fair! Though this trick could have been accomplished using almost any other sufficiently bright star, Arcturus was chosen, for the fact that its light takes almost 40 years to travel the distance to Earth, through space, and, the last time that the World's Fair was held in Chicago, was 40 years prior.

One of the more interesting things to me about Arcturus is that, though it is one of the many, more familiar stars of our Milky Way galaxy - it is not, originally, from 'here'; it is, literally, an 'alien' star -- from another galaxy! Now - hold on, let's not let our imaginations get the best of us here...

But, how do we know, that, our old pal, Arcturus is actually a 'rogue visitor', from some other, far-off galaxy?

It's because Arcturus orbits our Milky Way galaxy at an oblique angle, almost exactly perpendicular to the plane of rotation of most of the other stars of the galaxy. This means that it doesn't carry the same angular momentum or velocity (speed and direction) of the majority of stars, native to the Milky Way. And, there's more. Lots more.

Our galaxy - a fairly typical, the barred-spiral galaxy is, actually, an aggregate of a small "collection" of once, separate, individual galaxies!

You see, galaxies move through the universe in clusters, which are gravitationally bound to a common center of gravity, created by an original mass - say, a hypothetical, binary galactic pair.

Since all matter in the universe is gravitationally attracted to all other matter, the original, revolving pair, would soon have given in to the increasing 'force' of gravity generated by the pairs' decaying orbits, and, eventually collapsed together to form what we currently know as the Milky Way galaxy. (There may be other ways for stars to wind up as 'intergalactic rogues', such as, by gravitational sling-shot-ing, but it doesn't seem to be the case, here). But each galaxy of the original, binary pair would have possessed its own, specific inertia, as well as, specific mass, and a specific plane of rotation, bisected by a specific axis of rotation.

During the merger, most of the stars from both member galaxies would, over time, have assumed a common motion about the now-merged, galactic cores. But some stars, being farther away into the outer periphery of either galaxy, would have strayed, slightly, due to the effects of the differences of the combined angular momentums of the pair, and assumed their own orbits about the galactic core - as did Arcturus - along with 50 other known, stray stellar masses! These 51 stars are known as the "Arcturus Stream".  Other such streams are thought to exist, but these are so distant, relative to the Arcturus Stream, that they remain undetected.

Nevertheless, our Milky Way galaxy - our 'home' galaxy - has adopted these intergalactic wanderers as its own, which, is just as it should be, in my opinion, and I'm O.K. with Arcturus (much like, myself, in a way), as one of good ol' Sol's, 'intra'-galactic, adopted brothers!
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