Constellation of the Month: Hercules

May 31, 2013 Leave a comment

The month of June has the shortest nights of the year (for northern hemisphere stargazers), but there’s still plenty to see if you wait till the sky gets dark after midnight.

Sitting high in the south – almost directly overhead – during June is the constellation of Hercules.

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The body of Hercules is made up of four stars in an asterism known as The Keystone. The four stars in The Keystone, like all the star in Hercules, are not especially bright, so the pattern doesn’t stand out all that clearly. To find it draw a line from the bright orange star Arcturus to the bright white star Vega. Hercules sits about 2/3 of the way along this line.

Once you find the Keystone try and trace the four lines that come off each corner, Hercules’s arms and legs.

But the most interesting feature in Hercules is the faint fuzzy patch known as the Great Globular Cluster in Hercules, M13 (marked with a + above).

M13 lies on a line drawn between two of the stars of the Keystone, ζ and η Her. It’s just visible to the naked eye in dark sky conditions (which you won’t get during the summer months) but is easily found using binoculars. It will look like a fuzzy out-of-focus star.

In fact it is a globular (globe-shape) cluster of around 300,000 very old stars, orbiting our galaxy.

If you’ve got a powerful telescope then you should be able to make out individual stars within this cluster.

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Mercury, Venus, Jupiter in the evening sky, May 2013

May 26, 2013 Leave a comment

This evening, and for the next few evenings, just as the sky begins to darken after sunset, you’ve got a chance to see three of the five naked-eye planets side by side.

The two brightest naked eye planets (Venus and Jupiter) are close together, separated by only a few degrees, closing to 1° on 28 May (in what we call a conjunction). This should make them very easy to spot, low in the NW from around 30 minutes after sunset. In fact they’re close enough together that you could fit them both in one binocular field of view.

Mercury, however, might be trickier to spot. As the faintest naked-eye planet it will lurk in the twilight sky unseen for many people, just above the two brighter planets.

Remember, if you’re observing with binoculars or a telescope make sure you wait until the Sun has fully set

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Partial Lunar Eclipse Tonight, 25 April

April 25, 2013 Leave a comment

There’s a partial lunar eclipse tonight, visible from the UK, as well as from the rest of Europe, Africa, Asia and Australia.

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It won’t be hugely dramatic, as it’s only a partial eclipse of the Moon, not a total one. Even total lunar eclipses are far less grand than total solar eclipses, unfolding over several hours rather than minutes, and turning the Moon a deep red rather than making it vanish altogether.

And for partial lunar eclipses, like tonight’s, all we’ll see is a slight darkening of the edge of the Moon, what we call the “limb”.

Nevertheless it’s worth watching out for if you have clear skies. And the best thing of all is that light pollution isn’t really an issue; you’ll see it just fine from a city.

Here are the timings:

Penumbral Eclipse Begins: 18:03:38 UT
Partial Eclipse Begins: 19:54:08 UT
Greatest Eclipse: 20:07:30 UT
Partial Eclipse Ends: 20:21:02 UT
Penumbral Eclipse Ends: 22:11:26 UT

Remember that these times are in universal time (UT) which is the same as GMT, so add one hour on for BST.

Best time to look is between 9pm and 9:20pm BST.

Image from NASA’s eclipse site.

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Happy Birthday Hubble! Top Five Spring Telescope Targets

April 23, 2013 Leave a comment

The iconic Hubble Space Telescope (HST) was launched 23 years ago on 24 April 1990, and ever since has been returning breathtaking images of the cosmos as well as world-changing science. It is, without a doubt, one of the most successful scientific instruments ever built.

To celebrate its 23rd birthday here is a list of five stunning celestial objects visible over the next couple of months that you can find for yourself using a small earth-based telescope. Most of these objects will look like nothing more than diffuse grey smudges in the field of view of your eyepiece, but I’ve illustrated this post with some HST images of the same objects, to show you what they really look like. Despite the fact that your telescope can’t ever show anything as stunning as an HST image, there’s something even more wonderful about seeing these objects in real time, for yourself, not mediated via a computer screen.

1. Saturn

Hubble view of Saturn
Hubble view of Saturn

Rising around 2030 local time at the end of April, and 1800 local time at the end of May, Saturn is visible in the evening skies throughout the Spring and into Summer. At the moment Saturn’s rings are tilted very favourably towards us, presenting a striking view. Through a very small telescope – or binoculars on a tripod – Saturn might appear as nothing more than a oval, or at best a circular disk with handles, but most modest telescope should show the disk of the planet and the rings, and even Saturn’s largest moon, Titan.

2. Sombrero Galaxy, M104

Sombrero Galaxy, M104
Sombrero Galaxy, M104

The stunning Sombrero Galaxy in the constellation Virgo gets to its highest above the horizon around 2330 in late April, and 2130 in late May. It’s one of the brighter galaxies in the sky, and so even a medium sized telescope should show up the dark dust lane obscuring the view of the central bulge of the galaxy. This dust lane is actually a ring that surrounds the galaxy, and is probably where most of the star-forming takes place, as it is composed of atomic hydrogen and dust.

3. Ring Nebula, M57

The Ring Nebula, M57
The Ring Nebula, M57

Located in the constellation of Lyra in the Summer Triangle, the Ring Nebula (Messier number 57) is a striking object in medium or large telescopes. It rises from low in the NE mid evening to almost directly overhead by the time dawn begins to brighten the sky. The Ring Nebula is a great example of a planetary nebula, so-called as it looks like the disk of a planet when seen through modest telescopes. However this name is completely misleading, as the gas in this nebula was puffed off by a red giant star just before it died and collapsed into a white dwarf, a fate that awaits the Sun in 5 billion years or so.

4. The Great Globular Cluster in Hercules, M13

The Great Globular Cluster in Hercules, M13
The Great Globular Cluster in Hercules, M13

This spherical collection of around 300,000 stars is one of the best examples of a globular cluster in the sky. It’s high in the SE sky during the evenings of April and May, and continues to be visible into the Summer. M13 is at the very limit of naked eye visibility, and small telescopes show it off beautifully. In fact, this is one object where a smaller earth-based telescope gives you a better overall view of the object than the mighty HST. Hubble has such a high magnification that its field of view is very small. This is fine when you’re looking for tiny faint galaxies millions of light years away, but a nearby globular cluster presents problems; it’s simply too big to fit into the field of view. Nevertheless, this spectacular HST image shows the heart of M13, and the stunning array of stars that make up this beautiful object.

5. The Eagle Nebula, M16

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Pillars of Creation in The Eagle Nebula

OK, OK, so maybe this is more strictly speaking a late summer object, but it is visible pre-dawn in late May, low in the south, in the constellation of Serpens. Despite the unsocial hours it keeps at this time of the year, it still has to be included in any top-5 list of Hubble objects. The iconic “Pillars of Creation” image, taken by HST in 1995, is one of the most widely viewed of all Hubble images. It shows giant pillars of gas within the Eagle Nebula within which new stars are being born. However it’s a pretty tricky nebula to see through a telescope. There’s a star cluster within it that you’ll make out even in light polluted skies but to see it best you’ll need to head to a dark stargazing site and be patient.

For maps and tips about how to find these objects, and hundreds more like them using binoculars or a telescope check out my book, Stargazing for Dummies.

UPDATE: I just realised; there are people alive today with degrees in astrophysics who weren’t yet born when the Hubble Space Telescope was launched in 1990!

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Light Pollution and the Loss of Wilderness

April 21, 2013 Leave a comment

Today marks the 175th anniversary of the birth of John Muir, the Scottish-born American naturalist, writer, and advocate for the preservation of wild land.

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The protection of our wildernesses landscapes (defined as anywhere you cannot see the intrusion of human activity) is more important than ever, with the spread of suburbia and the urbanisation of more than 50% of the world’s population.

But one measure of what makes a wilderness has to-date been largely ignored: that of the darkness of the night sky. After all, if you can see the sky glowing orange at night then you are seeing the intrusion of human activity, and you can’t consider the land you’re in a true wilderness.

John Muir’s legacy as the founding father of the conservation movement lives on today, in part in the organisation The John Muir Trust.

The JMT estimates that the amount of Scotland’s landscape that is wilderness is rapidly diminishing, dropping from 31% of Scotland to 28% between 2008 and 2009, but I think if you added in the spread of man-made light pollution the situation would be decidedly worse.

I am fortunate to have been awarded the JMT’s Bill Wallace award to help fund a trip later this year (once the skies get dark again after the bright summer nights) to map light pollution in one of Scotland’s most wild landscapes, between the JMT properties of Quinag and Sandwood Bay.

Hopefully this project – the first of its kind in this remote area – will shed some light on the problem of the loss of our wilderness nightscapes.

Categories: Dark Places, Light Pollution Tags: , , , , , ,

Constellation of the Month: Leo the Lion

April 6, 2013 Leave a comment

Head outside during April just as the sky gets properly dark and sitting high in the south is the constellation of Leo the Lion.

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Leo is well-known as it’s one of the signs of the zodiac, and therefore one of the constellations through which the planets, Sun and Moon pass over the course of the year.

Leo is also well-known due to its most prominent feature, a pattern of stars within the constellation (called an asterism) known as The Sickle, which looks like a backwards question mark, with the bright star Regulus as the dot.

Regulus is known as the king star, and is one of the brightest stars in the sky, shining blue-white in late winter and spring.

Within the constellation of Leo are two groups of galaxies, marked as 1 and 2 on the chart above.

1. The Leo Triplet: M65, M66, and NGC3628
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2. The M96 Group: Including M95 & M96
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Any of these galaxies can be seen with even a small telescope, but their detailed structure can only really be seen in larger scopes.

Enjoy the spring skies, and happy galaxy hunting!

Maps and descriptions like this one for each of the 88 constellations can be found in my new book, Stargazing for Dummies. Click on the image on the right for more info.

Categories: General Astronomy, Stargazing Tags: , , , , , ,

Win a Signed Copy of Stargazing for Dummies

April 5, 2013 1 comment

To celebrate International Dark Sky Week I’m giving away a signed copy of my book, Stargazing for Dummies!

For a chance to win a copy, tweet “#stargazing @darkskyman …” followed by your best stargazing memories.

The competition is open to all my followers on Twitter for the duration of Dark Sky Week 5-11 April 2013, and I’ll draw the lucky winner at random some time on 12 April.

Here is a selection of some of your stargazing memories so far:

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