Crash Notes

Horses with Bicycle

There will be one final blog post on this site, after that I will no longer blog here again.

Thanks for the likes to so many posts and for allowing Crash Course to be read by you. I have also enjoyed following and reading your creative blogs as well.

My final post will be this Saturday, regarding Sunday’s full moon and eclipse. It’s a good topic to end on.

Regards,

Crash

 

Astronomy: The Week Ahead – Sun 30 Aug to Sat 05 Sep 2015

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Sunday August 30

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The Moon will rise in perigee tonight, due east. This is the Moon’s closest point to us in its monthly orbit. But look to Libra in the southwest. Saturn in a telescope is a great sight. The ringed planet is leaving us until next season, and will soon disappear into the glare of sunset. While you can, also compare the color of Scorpius’ star Antares.

Monday August 31

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Tonight Neptune is at opposition. The Earth lies directly between Neptune and the Sun. That means Neptune rises at sunset, is in the sky all night, and sets with sunrise. This is the best time to view the distant world! Here you can see it low in Aquarius, and how to use two of the constellation’s stars to point to it. Neptune is at magnitude 7.8, and can be seen in binoculars, but it is much easier to recognize its blue tone with a telescope. It is only 2.4 arcseconds in size, and with high power will appear a small bluish disk. The planet is its closest to us tonight, at almost 29 AU (astronomical units; 1 AU is the distance from the Earth to the Sun).

Tuesday September 01

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Venus is at its longest western elongation today, at 25 degrees from the Sun. Find it in the predawn sky in Cancer, near the head of Hydra, and below Gemini the twins. That red “star” nearby is Mars. Venus is inside our orbit just over 30 million miles away, and shows a very generous 51 arcseconds in size, as a 10% illuminated crescent. If you can view it through a telescope, you’ll be in for a visual treat! Mars is outside our orbit 150,000 million miles away, showing only a 3.7 arcsecond size disk. You can imagine a point during the year when the earth would be between the two!

Wednesday September 02

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Here’s a challenge for those viewing through telescopes in somewhat dark evening skies. NGC globular clusters 7006 and 6934 lie in the constellation Delphinus, roughly between Altair in Aquila, and Enif in Pegasus. Both are small, at 3.6 and 7.1 arcminutes, respectively. They shine at magnitudes 10.6 and 8.9. Both will be unresolved, you can’t see individual stars in them. So, they will both appear as somewhat granular, fuzzy glows.

Thursday September 03

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Lying between the paws of the Great Bear, Ursa Major, and the twins of Gemini, is the dim constellation Lynx, the cat. It has only one star brighter than magnitude 4.5, Alpha Lyncis, at magnitude 3.12 and 223 light years distant. It is a supergiant star, at 118 solar radii, and has the luminosity of 1622 suns!

There are only four main stars in the constellation, and they seem to get dimmer as you progress from Alpha. Can you make out the figure? This area has many dim open clusters and one famous globular cluster, which we’ll discuss Saturday.

Friday September 04

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How far can you see with the “naked eye”? Try for M31, the Great Andromeda Galaxy. Distance estimates range from 2.3 to 2.9 million light years. It will appear as a dim fuzzy patch, a short hop above the orange star Beta Andromedae. Find the sweep of the constellation Andromeda between the famous ‘W’ of Cassiopeia, and the Great Square of Pegasus. Once you identify the two arc comprising Andromeda, jump up from the star Beta, to dimmer star just above it, the up again about the same distance. Do you see the dim elongated glow? If so, grab some binoculars and try again.

Saturday September 05

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Here’s another challenge object. NGC 2419 is a globular cluster in the constellation Lynx. It measures a bit over 2 arcminutes in size and shines dimly at magnitude 10.4. It appears unresolved in most amateur telescopes, but will break up into individual stars at high power in larger telescopes. Thought to be 200,000 light years from Earth, it is the farthest such object in our galaxy. Most globular clusters in our galaxy are less than 1/3 that distance. Speculation exists that it was captured from another passing galaxy, and has been named “Intergalactic Wanderer.”

Happy viewing!

Crash

Astronomy: The Week Ahead – Sun 23 Aug to Sat 29 Aug 2015

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Sunday, August 23th:

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The bright star near the moon is Antares in the constellation Scorpius the Scorpion. You’ve got about another month or two to see this uniquely summer star for us in the Northern Hemisphere, during the evening hours. Antares is the brightest star near the moon tonight, while the other nearby bright beauty is the planet Saturn.

If you’re in the Northern Hemisphere, Antares and Saturn are visible in the southern to southwest sky as night begins. If you’re in the Southern Hemisphere, they’re more overhead for you.

The moon has now passed the first quarter phase and now exhibits a slight curvature to its terminator line – the line between dark and light on the moon. This moon phase is called waxing gibbous. The waxing gibbous moon, Antares and Saturn will drift westward throughout the night, to set at late evening or round midnight at mid-northern latitudes.

Like all stars, Antares sets some 4 minutes earlier with each passing night, or 2 hours earlier with each passing month. By October, this star will be tough to spot in the southwestern twilight after sunset.

In ancient Chinese thought, the summer season was associated with the direction south, with the element fire, and with the color red. No wonder, then, that this reddish star in the south each summer – beautiful Antares – was considered the Fire Star of the ancient Chinese.

Antares appears as a bright reddish star that rides relatively low in the south throughout our northern summer. We know it as a great ball of gases, a thermonuclear cauldron radiating unimaginable amounts of energy into the blackness and vastness of space.

Yet to us – as to the ancient Chinese – Antares appears so near the southern horizon that we must view it through a great thickness of air. The air through which we view Antares causes this star to twinkle rapidly! On any summer evening, if you see a bright red star low in the south that’s twinkling fiercely … it’s probably Antares.

The basics: The bright star near the moon on August 23, 2015 is Antares, brightest star in the constellation Scorpius. This star can be seen near the moon tonight from around the world.

Monday, August 24th:

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The moon can be found above the famous Stinger stars of Scorpius the Scorpion. These stars are called Shaula and Lesath.

As seen from mid-northern latitudes in North America, the Stinger stars loom close to the southern horizon at early evening, a good fist-width below tonight’s waxing gibbous moon. Depending on where you live worldwide, the moon’s position relative to the Scorpion’s Stinger stars varies somewhat.

If you live in Europe or Africa, the moon appears offset closer to Antares, Scorpius’ brightest star.

Asian viewers see the moon even more offset toward Antares.

Those residing in the Southern Hemisphere will see the moon, Antares and the Stinger stars high overhead, not close to the horizon.

When the moon drops out of the evening sky – toward the end of the first week in September – you can use these same Stinger stars to envision the constellation Scorpius, with its graceful curved tail. Plus, you’ll be able to plus star-hop to two beautiful deep-sky treasures: the star clusters M6 and M7.

Your binoculars are perfect for finding M6 and M7, assuming you have a dark sky. They fit within a single binocular field of view.

Your binoculars are perfect for finding M6 and M7, assuming you have a dark sky. They fit within a single binocular field of view.

In the lore of the skies, the Scorpion’s stinger put Orion the Hunter to death.

According to another version of the tale, Orion was accidentally killed by his lover, Artemis.Ophiuchus, the constellation to the immediate north of Scorpius, is said to depict the doctor Ascelpius, who tried to bring Orion back to life. Yet Hades, the god of the Underworld, appealed to Zeus to forbid Ascelpius from raising the dead, for the practice goes against the natural order of things.

The constellation Scorpius is opposite in our sky to the constellation Orion, which is up before dawn now. See the three medium-bright stars at the center of the constellation Orion? Those three stars are Orion’s Belt, and they always point to Sirius, the Dog Star and sky’s brightest star.

The constellation Scorpius is opposite in our sky to the constellation Orion, which is up before dawn now. See the three medium-bright stars at the center of the constellation Orion? Those three stars are Orion’s Belt, and they always point to Sirius, the Dog Star and sky’s brightest star.

The basics: On August 24, 2015, the moon is above the famous Stinger stars – Shaula and Lesath – of the constellation Scorpius the Scorpion.

Tuesday, August 25:

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Venus – the second planet outward from the sun and brightest planet visible in Earth’s sky – swung in between Earth and the sun. At that time, Venus transitioned out of Earth’s evening sky and into our morning sky. Unless you have special equipment, you probably haven’t seen Venus for a few weeks.

After having been lost in the sun’s glare for several weeks, Venus returns to visibility in the morning sky this week (beginning around August 26, 2015). On that approximate date – or on a morning around that date – you might see Venus climbing up above the eastern horizon an hour or so before sunrise – if you have an unobstructed eastern horizon and clear sky.

If you miss Venus this week, look for it to appear in the morning sky someday soon.

What will Venus look like before dawn? Here it is shortly before it slipping into the sunset in early August. This is Venus (brightest), Jupiter and Mercury low in the twilight on August 3, 2015. Photo by Peter Lowenstein in Mutare, Zimbabwe.

What will Venus look like before dawn? Here it is shortly before it slipping into the sunset in early August. This is Venus (brightest), Jupiter and Mercury low in the twilight on August 3, 2015. Photo by Peter Lowenstein in Mutare, Zimbabwe.

Just don’t mistake Sirius – the brightest star of the nighttime sky – for the planet Venus. Sirius sparkles in the southeast, while Venus shines with a steadier light almost due east. Although Venus is actually brighter than Sirius, Venus might be the harder of the two to spot in the morning sky right now, because Venus sits closer to the glare of sunrise. Click here for more information about Sirius in the morning sky.

The illustration below enables you to get some perspective of Venus’ and Earth’s orbits around the sun. We’re looking down upon the plane of the solar system from the north side. From this vantage point, the planets revolve counter-clockwise around the sun.

Not to scale. The radius of Venus’ orbit is about 0.72 of Earth’s distance from the sun (0.72 of an astronomical unit).

Not to scale. The radius of Venus’ orbit is about 0.72 of Earth’s distance from the sun (0.72 of an astronomical unit).

The passage of Venus between the Earth and sun took place on August 15, 2015. Astronomers call this an inferior conjunction of Venus. At such times, Venus in its smaller and swifter orbit passes in between the Earth and sun. We should mention that only planets that orbit the sun inside of Earth’s orbit (Mercury and Venus) have inferior conjunctions.

After inferior conjunction, Venus always moves westward of the rising sun in our sky until reaching itsgreatest western elongation (46o) – farthest angular distance from the rising sun – some 72 days later.

Venus will next reach greatest western (morning) elongation on October 26, 2015. It’ll look like a miniature half-lit quarter moon through the telescope. That’s because Venus’ disk always appears about 50% illuminated by sunshine at any greatest elongation.

Midway between inferior conjunction and greatest western elongation, Venus will shine at its brightest as the morning “star” on September 21, 2015. That’s in spite of the fact that Venus’ disk is only about one-quarter illuminated by sunshine whenever it’s midway between an inferior conjunction and a greatest elongation.

This brilliant world will remain in the morning sky until reaching superior conjunction on June 6, 2016, to transition back into the evening sky.

The basics: Starting around August 26, 2015, start watching for dazzling Venus to illuminate the sky before sunrise.

Wednesday August 26th:

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Every year, during the last week of August, a first hint of the changing of the seasons can be seen in the predawn sky: Orion the Hunter and Sirius the Dog Star. The very noticeable constellation Orion the Hunter rises before dawn at this time of year, recognizable for the short straight line of three stars that make up Orion’s Belt. And the sky’s brightest star Sirius – sometimes called the Dog Star because it’s part of the constellation Canis Major the Greater Dog – follows Orion into the sky at or close to dawn. Have you noticed a very bright, madly twinkling star in the predawn sky? Many do, at this time of year. That star is Sirius. It’s so bright that, when it’s low in the sky, it shines with glints of red and flashes of blue – very noticeable!

Orion and the nearby star Sirius will become visible in the evening by northern winter (or southern summer). But presently the Hunter and the Dog Star lord over the southeastern sky at dawn’s first light.

The brightest star in this photo is Sirius, the sky’s brightest star. Notice Orion’s Belt stars in the upper left of this photo and how the Belt stars always point to Sirius. Photo courtesy of Leif Boracay.

The brightest star in this photo is Sirius, the sky’s brightest star. Notice Orion’s Belt stars in the upper left of this photo and how the Belt stars always point to Sirius. Photo courtesy of Leif Boracay.

Orion was low in the west after sunset around March and April. By June each year, this constellation is behind the sun as seen from Earth. Orion only returned to visibility in Earth’s sky about a month ago (see our July 29 sky chart). When a constellation becomes visible again, after being behind the sun, it always appears in the east before sunrise.

Because – as Earth orbits the sun – all the stars rise two hours earlier with each passing month, Orion is now higher at dawn than a month ago.

As seen from the Northern Hemisphere, Orion precedes Sirius the Dog Star into the sky. After Orion first appears at morning dawn, you can count on Sirius to appear in the morning sky a few weeks later. You should be able to see Sirius at or before dawn right now – unless you live at far northern latitudes. But even there, it won’t be much longer!

Bottom line: Every year in late August, look for Orion the Hunter and Sirius the Dog in the early morning sky! Orion’s three prominent Belt stars always point to Sirius.

Thursday, August 27th:

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In both the evening and morning sky, try watching for Earth’s shadow. Earth’s shadow is a deep blue-grey, darker than the twilight sky. The pink band above the shadow – in the east after sunset, or west before dawn – is called the Belt of Venus.

Earth’s shadow can be seen any clear evening ascending in the eastern sky at the same rate that the sun sets below the western horizon.

The shadow of the Earth is big. You might have to turn your head to see the whole thing. And the shadow is curved, in just the same way that the whole Earth is curved. Earth’s shadow extends hundreds of thousands of miles into space, so far that it can touch the moon. Whenever that happens, there’s an eclipse of the moon, like the one coming up in September.

Check out Earth’s shadow – in the east at sunset or in the west at sunrise – next time you have a clear sky. I often see it while out on the streets of my town as the sun is setting.

By the way, the image at the top of this post shows more or less the same moon phase that you’ll see tonight. It’ll be a waxing gibbous moon that’ll be visible in the east after sunset this evening. The full moon will come on August 29, 2015, to present the first of this year’s full supermoons.

The basics: Watch for the curved blue-grey line of Earth’s shadow at dawn and dusk. The pink coloration above the shadow is called the Belt of Venus.

Friday, August 29th:

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Supermoon ahead! The full moon of August 29, 2015 will be the first of this year’s three full supermoons. It’s a full moon near perigee, or near its closest point to Earth for the month. Like it or not, modern skylore dictates that these sorts of moons are called supermoons.

But will your eye see that the moon is bigger on the night of August 29? Well … it depends. Are you an incredibly careful observer? Have you watched the full moon over a period of months, leading up to now? If so you can discern the extra-large size of the supermoon using just your eye.

The closest and largest full supermoon of them all will fall on September 28, to stage a total eclipse of the moon. Some will call it a Blood Moon eclipse.

In North America, we often call the August full moon the Sturgeon Moon, Corn Moon or Grain Moon. The August 2015 full moon is also the first of three full-moon supermoons in 2015. Previously, we had three new moon supermoons in January, February and March, 2015. The full moons on August 29, September 28 and October 27 all enjoy the supermoon designation because the centers of these full moons and the center of Earth are less than 361,836 kilometers (224,834 miles) apart. The closest supermoon of the year comes with the September 28 full moon, presenting a moon that’s only 356,877 kilometers (221,753 miles) from Earth.

Super cool super-moonrise composite from Fiona M. Donnelly in Ontario. This was the supermoon of August, 2014.

Super cool super-moonrise composite from Fiona M. Donnelly in Ontario. This was the supermoon of August, 2014.

Details on the August, 2015 full supermoon The full moon falls at the same instant all over the world: August 29 at 18:35 Universal Time.

Clock time for this full moon – and every full moon – varies by time zone. For London, the moon turns full at 7:35 p.m. BST on August 29, at which time the afternoon sun shines in the west and the moon has not yet risen in the east. For the U.S., the moon turns full on at 1:35 p.m. CDT on August 29, when the sun shines way up high and the moon lies on the other side of the world, beneath our feet.

Technically speaking, the moon turns full at the instant that the moon lies most opposite the sun for the month. Because the moon stays more or less opposite the sun throughout the night, watch for a full-looking moon in the east at dusk, highest in the sky around midnight and low in the west at dawn. On the nights immediately before and after full moon, the moon still looks plenty full to the eye.

When is perigee, the moon’s closest point to Earth? In August, 2015, the moon’s perigee comes less than one day after full moon, on August 30 at 15:24 Universal Time.

The close coincidence of full moon and perigee makes this August full moon a supermoon.

By the way, no particular effects are expected from this extra-close full moon… unless you have the mass of an ocean! In that case, gravity will come into play. In other words, because it’s a supermoon, and relatively close to Earth, this month’s full moon will pull harder than usual on Earth’s oceans. Expect higher-than-usual tides to follow this full moon by a day or so. By the way, any full moon mirrors the sun’s path across the sky for six months hence.

And so here’s another cool thing you can notice about the August 29 full moon. As seen from the Northern Hemisphere, this full moon will follow the low path of the winter sun. As viewed from southerly latitudes, the moon will follow the lofty path of the summer sun.

Enjoy moon-watching tonight and in the next few evenings!

The basics: The full moon on August 29 ushers in the first of three full-moon supermoons in 2015. Full moon is August 29, 2015, at 18:35 Universal Time. The moon’s perigee or closest point comes on August 30, at 15:24 Universal Time.

Saturday, August 29th:

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In North America, the August full moon is often called the Sturgeon Moon, Corn Moon or Grain Moon. Tonight – August 29, 2015 – if you’re in this hemisphere, it’s a super Sturgeon Moon you’ll see.

The full moons on August 29, September 28 and October 27 all enjoy supermoon status in 2015, because the centers of these full moons and the center of Earth are less than 361,836 kilometers (224,834 miles) apart. So it’s a super close full moon you’ll see on this night, dubbed, in modern skylore, a supermoon.

Some dislike the term supermoon, but I think it’s fun. But is it rare? No. We have three full supermoons this year, and we already had three new moon supermoons in January, February and March, 2015.

The closest supermoon of the year will arrive with the September 28, 2015 full moon. It’ll be only 356,877 kilometers (221,753 miles) from Earth.

Moreover, the closest and largest full supermoon of the year on September 28 will stage a total eclipse of the moon. This will be the fourth and final eclipse of a lunar tetrad – four total lunar eclipses in a row, each separated by six lunar months (full moons), with no partial lunar eclipse in between. Some refer to the four eclipses of a lunar tetrad as Blood Moons.

Technically speaking, North America won’t see the moon at the instant it turns full because it will happen during our daylight hours, when the moon is below our horizon and beneath our feet. The worldwide map below shows you the day and night sides of the world at the instant of the August 29 full moon (18:35 Universal Time). At United states time zones, that translates to 2:35 p.m. EDT, 1:35 p.m. CDT, 12:35 p.m. MDT or 11:35 a.m. PDT. You have to be on the nighttime side of the world to see the moon at the exact instant that it turns full.

Everyone around the word, however, will see a full-looking moon in the east at dusk or nightfall, highest up for the night around midnight and sitting low in the west at dawn. The moon stays more or less opposite the sun for the duration of the night on August 29, 2015.

The basics: the August full moon will be the Sturgeon Moon. if you’re in the North American hemisphere and this super Sturgeon Moon will be seen on August 29, 2015.

Happy viewing!

Crash