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Full Transcript below

Dr Ian ‘Astroblog’ Musgrave returns with your essential guide to the August night sky — including the Perseid meteor shower and a Total Solar Eclipse crossing the Northern Hemisphere. Plus, Mars sweeps past the Crab Nebula and the open cluster M35, Saturn begins opening its rings ahead of September opposition, and Venus dominates the evening twilight on its way to greatest elongation. The Moon occults Elnath, Beta Tauri, on the 9th, and in the Tangent, Ian explains how fragile organic molecules like sugar and ethanol survive the fiery birth of a new star.

In This Episode:

• Perseid Meteor Shower: peak viewing tips (best from the Northern Hemisphere; limited visibility from Australia)
• Total Solar Eclipse: crosses Iceland and Spain — how to watch via livestream if you’re not in the path
• Moon Phases: Last Quarter, New Moon, First Quarter, Full Moon, and the Lunar X
• Evening Skies: Venus approaches greatest elongation; Jupiter absent until next month
• Morning Skies: Mars passes the Crab Nebula and M35; Saturn’s rings begin opening
• Deep-Sky Spotlight: Scorpius, Sagittarius, and the constellation Aquila the Eagle
• Indigenous Astronomy: Aquila in Koori and Wurrung sky-lore
• The Occultation of Elnath by the Moon, August 9
• The Tangent: How sugar and other organic molecules survive the birth of a new star
• Coming up: a road trip to Broken Hill for an interview with Saturn storm-tracker Trevor Barry

Full Transcript: Introduction

Welcome to episode 239 of Astrophiz. My name is Brendan O’Brien and Astrophiz is produced on Yorta Yorta, Pangarang and Kaurna country. We celebrate the first astronomers of this land.

Monthly, we explore the universe with the world’s leading scientists. For transcripts and more, visit Astrophiz.com.

And here is Dr. Ian Musgrave with your August SkyGuide.

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Brendan: Hello, Ian.

Ian: Hello, Brendan. Great to be speaking with you again, Ian.

Brendan: Can you tell us, mate, what’s up in the sky for the month of August?

Ian: Well, this August, the planetary action is mostly in the morning skies, although in the evening skies, we’ve got Venus very prominently in the early evening sky, and Saturn joins it later in the evening. Jupiter has vanished from sight and won’t be seen again until next month. But in the morning, you’ve still got a good view of Saturn and a good view of Mars.

The August Moon Phases

Ian: Okay, let’s start as I normally do with the Moon.

• August 6: Last Quarter Moon — ideal for stargazing
• August 13: New Moon — also ideal for stargazing. There’s going to be a total solar eclipse in the Northern Hemisphere. So if you happen to be in Iceland or Spain, you’ll be blessed with a solar eclipse. We will see no partial eclipse, but we can watch it via live streaming.
• August 20: First Quarter Moon, and we’ll be able to see the Lunar X again. However, it’ll be in twilight on the East Coast and in daylight in Western Australia. But by the time twilight comes in WA, it’ll still be visible.
• August 28: Full Moon. And again, there’s a partial lunar eclipse, which is not visible from Australia. So we miss out on all the eclipse action this month.
• Moon at Perigee: August 10
• Moon at Apogee: August 22

Ian: Now to back up to the Lunar X and also the Lunar V, these are typically visible from about four hours from the starting time. And on August the 20th at Eastern Standard Time, it’s about 5.30 when the Lunar X becomes visible, 5 o’clock for Central Time and 2.30 for Western Australia. That’s completely in daylight. But for the AEST and ACST, it’s in very bright twilight, but still visible, because it’s visible four hours later, as the twilight darkens you’ll be able to have a very good view of the Lunar X.

Evening Skies: Venus and Jupiter

Ian: Now turning to the evening sky, Venus is climbing higher and higher until about the 15th, when it reaches its greatest elongation from the Sun at 46 degrees east of the Sun, and it’s now easily visible well after the sky is fully dark and also easily visible shortly after the Sun has set. In a telescope, Venus is a distinct half moon phase and will begin to show a waning crescent phase later on in the month.

On the 15th, Venus is less than two degrees — that’s about two finger widths — from the four day old waxing crescent Moon. So this will look very nice in the evening sky. And then later on, you’ll see Venus and the Moon lined up.

Jupiter is totally lost in the twilight glow and won’t turn up until late next month.

Morning Skies: Mercury, Mars and Saturn

Ian: So let’s now go to the morning sky. Mercury returns to the morning skies, but it remains low in the twilight and is difficult to see the entire month.

Mars is above the eastern horizon at astronomical twilight, so very easy to see in the morning. It’s now in Gemini, having left Taurus behind. And on the third, the red planet passes within 1.5 degrees — it’s a little bit over a finger width — of the Crab Nebula, the famous supernova remnant. But this is going to be a bit difficult in binoculars because it’s going to be low at the horizon and the Crab Nebula is around about magnitude eight. So unless you’re under deep, dark skies away from the suburbs, you won’t be able to see it.

However, between the 14th and the 17th, Mars is in about one finger width of the open cluster M35. This is a rather beautiful little cluster, and it’s easily visible in binoculars. Again, by this time, between the 14th and 17th, at astronomical twilight, Mars is sufficiently high above the horizon that the open cluster will be readily visible in binoculars.

Now, on the 9th, the crescent Moon is near Mars, very close to Elnath, the Beta Tauri. Actually, in one sense at this time, Mars is forming the tip of the second horn of Taurus the bull. So Elnath, Beta Tauri, is the tip of one of the horns. Very unprepossessing Sa forms the tip of the other horn, but Mars takes its place around this time. At the same time, in Australia, most of Australia will see an occultation of Elnath by the Moon. So you’ll get to see the Moon where Elnath should be, with Mars in the position of the other horn of the bull.

Brendan: Nice.

Ian: Now, Saturn under the heading of morning skies, even though it’s now visible in the evening skies, it’s rising about 10.30pm Eastern Standard Time at the start of the month in the Eastern skies, but it’s very low for most of the beginning of the month. And so it’s best seen and best for astrophotography in the morning skies, and around about 4am is when it’s highest. So that’s a good time to be looking with telescopes.

Of course, the weather is still cold, and with the cold still skies, it makes excellent astrophotography. As I said, the Saturn is beginning to open its rings. So although it won’t be as wide as in later years, it’ll still be giving us a nice view of the rings. And so if you’re up around four o’clock in the morning with your telescope, this is a brilliant time to image Saturn. And unlike the stars, Saturn doesn’t particularly care about moonlight, so you can image it at any phase of the Moon.

Brendan: Yes, exactly.

Ian: So the waning Moon is very near Saturn on the 4th. And by the end of the month, Saturn is beginning to rise about 8pm ahead of its September opposition. So even though it’s rising at 8pm, it’s not going to be good for telescopes until quite late in the evening when it’s sufficiently high to be undisturbed by the horizon blur and the turbulence.

Brendan: Now, it will be. I’m looking forward to it. And hopefully the rain will pour sufficiently — the scope out in my campaign to image Venus in its crescent phase is not doing very well at the moment. I’ve got one shot.

Ian: Exactly. T-Coronae Borealis — guess what? It still hasn’t gone bang, and it’s not looking like it’s going to, but I’ll keep you updated.

Brendan: We just keep waiting.

Ian: We just keep waiting.

Brendan: Okay.

Deep Sky: Scorpius, Sagittarius, and Aquila the Eagle

Ian: Of course, the standout in August is the Milky Way. It’s passing across the zenith in the early evening. Scorpius is just off the zenith, and the distinct teapot asterism of Sagittarius and Scorpius dominates the sky. Unfortunately, this means you’ll need to get a crick in your neck trying to watch them unless you’re lying on the ground with binoculars, which I highly recommend. Of course, being August, I also recommend having a ground sheet and rugged up quite warm.

I’ve talked about the major clusters in Scorpius and Sagittarius before, so I won’t go into them in any detail. But again, it’ll be glorious lying on the ground, tracing the length of Scorpius, going through the Pomet Cluster, the Trippid Nebula, and the M22, the amazing globular cluster, and then just looking at all the cool things you can see there.

So I’m going to talk about an entirely different constellation. So I’m going to look to the northern skies, which we rarely do, and the constellation of Aquila. Now, this constellation is faint, but the most notable stars are the bright star of Altair, a blue-white star, flanked by two dimmer but still bright stars. It’s very obvious, three stars in a line towards the northern hemisphere.

Now, the name Aquila means eagle in Latin, and in Greco-Roman mythology, Aquila is the bird that carries the use of thunderbolts. Now, the eagle motif of Aquila also appears in indigenous astronomy. For the Koori people of Victoria, Altair represented Bungil, the eagle hawk, and the stars to either side of him were his two wives, a pair of black swans. To the Wurrung people of Western Victoria, Altair was the son of Neolion, the Malipal, represented by the star Vega, and the stars on either side were his two wives. Altair may also represent an eagle in the Wurrung mythology as well.

Now, while there are no thunderbolts for this celestial eagle, Aquila covers a nice wave of the Milky Way. Unfortunately, there are no bright clusters or galaxies to enchant us, but if you sweep the area around Altair with binoculars under dark skies, you’ll be rewarded with faint but delightful star clouds. In dark sky locations, there is an E-shaped dark nebula west of Altair that is easily visible in binoculars.

Altair is also the vertex of a pattern of stars known as the Winter Triangle in the Southern Hemisphere, and the Summer Triangle for those of you in the Northern Hemisphere. This is made up of Altair itself, the bright star Vega, which is close to the northern horizon for us, and the bright star Deneb, which is even closer to the horizon and may be difficult to see in southern Australia. This large triangle encloses a large section of the Milky Way.

Meteors: The Perseids

Ian: Okay, meteors. The Perseid meteor is on this month. From the Southern Hemisphere, the Perseids are not readily observable. You can see them in Darwin and northern Queensland, but the radiant is under the horizon of many southern observers, and at most you’ll see one or two meteors. For those of you in the Northern Hemisphere, every person and their companion will be pointing out how to see the Perseids, so I’ll leave it up to them.

The Occultation of Elnath, August 9

Ian: So I’ll just finish with the occultation of Elnath, Beta Tauri. Now, again, this is on Sunday, August the 9th. The Moon is easily observable, even though it’s not too high above the horizon. It’s best seen from the east coast. Perth misses out entirely. Adelaide only gets to see it reappear from the dark side. The Moon is past last quarter. It’s low in the eastern sky, but still will be easy for binoculars and telescope observation. A telescope is best, unless you’ve got a horizon — you may find just binoculars appropriate.

So for most of the east coast, Elnath disappears behind the bright limb of the Moon approximately a bit after four o’clock, about a quarter to five, and then reappears approximately 5.30 or so. In Darwin, you actually see it disappear around about four o’clock and reappear about 4.30. And as I said, Perth misses out entirely. So maybe a little bit difficult unless you’ve got a clear horizon, but it’d be well worth observing. Elnath is relatively bright, so it’ll be very easy to see it reappear. And having this occur with bright Mars nearby will look very nice in the morning indeed.

Brendan: Excellent.

The Tangent: Sugar in Space

Ian: Well, I have a very brief tangent for you. Now, I’ve been talking a lot about star clouds and nebula that you’ll be seeing as you look up at the zenith with the Milky Way and Scorpius and also near Altair. But we know that in these star clouds, you not only have gas like hydrogen and a trace of helium and a few other things there, but we’ve been discovering more and more interesting molecules in our radio telescopes.

A while back, it was announced that ethanol had been detected, and everyone was getting excited, talking about how there’d be something like a million tequila slammers in a standard gas cloud, even though, of course, there would be about one molecule of ethanol per cubic kilometre. And more recently, they’ve discovered sugar in the gas clouds. So these are quite complex organic molecules. And, of course, sugar is very important in terms of the building blocks of life on Earth.

But that’s all very well. The discovery of these molecules by themselves, although interesting, is not the thing I wanted to talk about. What I wanted to talk about is the fact that these fragile molecules survive when newborn stars form. So, again, when a newborn star forms, the gas falls in, it gets denser and denser, and then you have the baby star ignite, and then it becomes very hot, and this massive heat wave sweeps out through the dust, evaporating ice as it goes, which is why the inner planets are all rocky and the outer planets are gas giants and ice giants.

But what about these fragile molecules of life? What happens to them? It turns out they survive. So these cocoons around the maybe stars are rich in these organic molecules and they survive. And so these primordial molecules formed in the depths of space survive into the cocoons around these baby stars, which can then go on to seed the new formed planets.

And so in terms of generating organic molecules on these baby planets, it doesn’t have to be all done by themselves. They can be seeded by molecules that have been gestating in the depths of space for eons, millions if not billions of years. So we know, for example, that there are organic molecules in meteorites are bringing organic molecules to Earth, and there’s a number of ways that organic molecules can be produced on the early Earth itself. But we’ve always thought that the molecules that we found in the deepest, darkest depths of space could not survive the conditions of the formation of the early Sun, but it looks like they can indeed.

So billion glasses of tequila, or those 10 million doughnuts worth of sugar, may very well be present in Earth’s prenatal cocoon, raining organic molecules down upon the surface of the baby Earth. And I find that quite amazing.

Brendan: It is.

Ian: So the next time you look up the nebula while you’re out in the bitter cold of winter and looking up at the clouds around Sagittarius, thinking that out there somewhere is not just ethanol and sugar and all these other molecules. They may be raining down on a baby planet somewhere as you watch.

Brendan: Beautiful. And the origins of life are everywhere.

Ian: Exactly.

Brendan: Thank you very much, Ian ‘Astroblog’ Musgrave. August is fantastic, and thank you for putting a sweet end to this month’s SkyGuide.

Ian: It was my pleasure, and sugar is something very much on my mind.

Brendan: Very good. Well, thanks, Ian. Good night, mate.

Ian: Good night, mate. We’ll catch you later. Cheers.

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Closing: Coming Up — Trevor Barry, Outback Astronomer

Brendan: And in two weeks, we have a fantastic interview for you when we are driving nine hours north up into the remote scrublands of Broken Hill to speak with Australia’s most famous outback astronomer, Trevor Barry, who has hand-built a powerful telescope and observatory and who has been providing NASA with optical science data on storms on Saturn to fill in the many scientific gaps that have been created since Cassini crashed into Saturn nine years ago.

I just can’t wait. And remember, Astrophiz is free, ad-free and unsponsored. Find us on Astrophiz.com or your favourite social media platform.

Keep looking up. Clear skies.

Brief Music Outro: “Radio Waaaaves”