Podcaster: Ralph, Paul & Jenny

Title : Awesome Astronomy’s April Sky Guide

Organization: Awesome Astronomy

Link : www.awesomeastronomy.com

Description: For the beginners this month Ralph takes a look at the Leo Lion who leaps across the sky all April. Leo hosts some nice colour contrasting binary stars (one with a gas giant planet of its own) and some galaxies to hunt down.

Next Jeni rounds up the planets that are visible in December: Jupiter Mars and Mercury at one of its most favourable viewing opportunities. The moon makes a not-to-be-missed passage through the Hyades Cluster on 10th April. And we round off with the Lyrid meteor shower and a last gasp chance of comet Catalina.

As spring is galaxy season, for the deep sky challenge Paul slews a scope through Virgo in a hunt for entire galaxies that can be seen with amateur telescopes. While the constellation of Virgo is quite indistinct it harbours a wealth of elliptical and spiral galaxies, culminating with the unique treat, Markarian’s Chain.

Bio: Awesome Astronomy is the show for anyone and everyone who has even the slightest interest in astronomy and science.

Join Ralph, Paul & Jeni for informative and fun astronomy programs telling you what to look out (and up) for every month as well as a main show dedicated to space and astronomy news. You can be guaranteed a passion for astronomy, simple explanations of complex and fundamental topics, space and science discussions, absorbing interviews with astronomers and astronauts who make the news and answers to listeners’ space questions.

Today’s sponsor: This episode of “365 Days of Astronomy” is sponsored by — no one. We still need sponsors for many days in 2016, so please consider sponsoring a day or two. Just click on the “Donate” button on the lower left side of this webpage, or contact us at signup@365daysofastronomy.org.

Transcript:

Paul: April is here once again and the night skies are getting noticeably shorter and brighter with every day that passes, but on the positive that does mean the evenings are warmer and those core chilling nights fighting the frost on your scope are all but behind us as are the winter constellations which set soon after the Sun, leaving us with a spring sky full of galaxies as our sky stares into the Virgo supercluster. We have a good meteor shower to look forward to and Jupiter, Mars and Saturn giving their best. But before we look at that, what has Ralph got for us in the beginners guide?

Ralph: Well this month we’re going to take a look at the constellation of Leo the Lion for our beginner’s guide. Much as Orion dominates the southern portion of the sky in winter, Leo, another large and unmistakable constellation dominates in spring. And as spring’s often called galaxy season, you won’t be surprised to learn that we’re going galaxy hunting this month.

As soon as it’s dark, Leo’s nice and high in the east and swings south to west as the night goes on. And it’s really easy to pick out as it does actually look like a crouching lion and has three stars brighter than magnitude 2.2 – Algeiba in Leo’s neck, Denebola at magnitude 2.1 in the lion’s tail and bright magnitude 1.4 Regulus in Leo’s front paw.

And we’ll start with that first star Algieba because this giant star not only has a planet twice the size of Jupiter in its system, but also a companion star. You can’t see the planet from Earth but a modest telescope will be able to split Algieba into two nice colour contrasting stars of orange & yellow. So give that a go.

Moving down the lion’s chest, we have the brightest star in Leo, Alpha Leonis, or Regulus. This is another binary star that can be split with any sized telescope at high magnification. The companion star’s only magnitude 8 but with an 8” scope or larger, you might even tease out a second yellow companion to Regulus

Moving onto Denebola in Leo’s tail. Denebola’s the 2nd brightest star in Leo. It has 75% more mass than our sun and it’s relatively young at only 400 million years old. For contrast, our sun is four and a half billion years old. Denebola rotates incredibly fast and, if you could see it close up, you’d see it bulges at its equator – similar to Jupiter.

Now, earlier I promised you galaxies and the cream of the crop in this part of the sky is a three for one offer known as the Leo Triplet that sits below the hind legs of the Lion

Here you’ll see three smudges of light in a medium sized telescope under low magnification, especially in dark skies. If you use a 5” or larger scope you’ll see that these are clearly individual galaxies.  It may be that you only see the brighter two at first, but spend a while getting used to this eyepiece view and you should find the third galaxy with averted vision – averted vision means looking to the side of the object you want to see to let your more light receptive peripheral vision reveal it.

In the Leo Triplet, the first of the brighter pair, Messier 65, is magnitude 10.3 and shows us a spiral galaxy tilted away from us.

Next to it, Messier 66 is brighter at magnitude 8.9 and another spiral galaxy, this time with a more favourable tilt, so large amateur scopes may even tease out the spiral arms & dust lanes, but even smaller scopes should see a nice bright core of billions of suns.

The final companion in the Leo Triplet is Sarah’s Galaxy, NGC 3628, which is the dimmest of the three at magnitude 14.8 and it’s a good test of your averted vision ability.  But seeing all three, 35 million light years away, in the field of view of the same eyepiece really is a treat.

Jeni: For the tour of the solar system this month, we begin with the king of the planets, Jupiter, who, this month, lies in Leo.  Jupiter was at opposition last month but is still very bright, at magnitude -2.4, and so would be a great target for those with small telescopes and binoculars.  With a rotation period of just 10 hours, for those fortunate to have apertures large enough to pick out the Great Red Spot, spending a whole night viewing the gas giant can be marvellous.  In real time, you can see the movement of the spot, something definitely worth doing.

Next on our list is Mars – not quite as bright as Jupiter, but still a good target for all at magnitude -1.  Mars is in Ophiuchus this month and will begin its retrograde motion across the sky before reaching opposition in May.

Just seven degrees to the east of Mars, at magnitude 0.3, you will find the ringed beauty that is Saturn.  Currently, the rings of Saturn are quite open, so there is certainly a lot to look at.

However, the real star of the solar system this month is Mercury, which reaches greatest eastern elongation in the middle of this month in the evening.  If you want to tick Mercury off your list, the coming month would be the opportune time as it reaches greatest elongation on the 18th, at magnitude -0.3.

Unfortunately, Venus is not really visible this month but on the morning of the 6th, the crescent moon occults the planet at around 7.30am.  This is not something that will be easy to see but if you fancy a challenge, go for it!

The Moon this month is new on the 7th, first quarter on the 14th, full on the 22nd and last quarter on the 30th.  On the 10th, the Moon will be in the Hyades cluster, and will occult three stars in an hour in the evening at around 9pm.  If you’ve never seen an occultation before, this would be a brilliant chance for you to try and see what all the fuss is about, as you have three opportunities in an hour – something particularly appealing to any imagers out there.  The stars in question are 1 and 2 Theta Tauri and HIP 21029.

And, of course, April brings us the Lyrid meteor shower, which peaks on the 21st, with the radiant to the west of Vega towards Hercules.  Interestingly, this is one of the oldest known meteor showers, with records of it dating back some 2700 years.  The zenithal hourly rate is around 10 however, we are going to have the light of the full moon to deal with.

Finally, we have comet Catalina, which currently lies in Perseus but is fading quickly – it’s last chance saloon if you want to catch her.  The comet is moving towards Capella and is about magnitude 11.

Paul: For our deep sky challenge this month we are looking at the the Virgo cluster of galaxies that can be found in the constellations of Virgo and Coma Berenices. Now Virgo is a pretty indistinct constellation that is best found by looking at the area between the stars Denebola in Leo, Arcturus in Bootes and Spica in Virgo, now in the middle of this triangle of stars is the Virgo cluster and a good star to pick out as a signpost to the cluster is Vindemiatrix which sits near the centre of that triangle slightly closer to Arcturus and Denebola.

There are a myriad of galaxies to look out here and those with bigger scopes will be able to lose themselves in leaping from one the other but here we will pick out three highlights. First of moving south east of Vindemiatrix we have M49, a large elliptical galaxy that was the first discovered of the Virgo cluster. Despite being 49 million light years away it is very bright and easily found, look out for surrounding galaxies such NGC 4469, 4526 and 4535.

Closer and to the west of the star we have five Messier galaxies is close proximity, M60 a bright elliptical 55 million light years away, M59 another elliptical at a similar distance, M58 a face on barred spiral which at 68 million light years was for a long time the furthest observed object. M89 and M90 sit close to each other, M89 being unusual as it is thought to be an elliptical galaxy that is almost a perfect sphere. M90 is a large and bright spiral galaxy.

Moving to the Northwest from Vindemiatrix we get to perhaps the jewel in the crown of the Virgo super cluster, Markarian’s chain.  Here you will find a spectacular line of galaxies that start in the west with M84 and 86 and flow away to the northeast with NGC4438 and 4435, then three fainter galaxies in the form of 4461, 4473 and 4477. After a gap you will find the large and bright M88 and not too distant from there M91.  To the south of the chain do look out for the monster that is M87, one of the largest galaxies known and certainly one of the largest near our own, which is utterly dwarfed by this massive elliptical.

So happy hunting and I wish you clear skies.

End of podcast:

365 Days of Astronomy
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