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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.

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

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

hs-1995-44-a-large_web
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!

Categories: Stargazing 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:

Categories: Stargazing Tags: , , ,

Comet PanSTARRS

March 8, 2013 Leave a comment

Over the next few weeks UK stargazers will have a chance to see a bright comet in the western sky at sunset.

The comet is called PanSTARRS C/2011 L4, or PanSTARRS to its friends, and was named after the PanSTARRS 1 (Panoramic Survey Telescope and Rapid Response System) telescope in Hawaii, which was the telescope used to discover the comet in 2011.

Since then Comet PanSTARRS has been nearing the Sun, heating up, and forming a long bright tail as the surface ices on the comet sublimate into gases.

Comet PanSTARRS has been visible in the southern hemisphere for a while now, but it’s only now that northern stargazers will get a chance to see it.

Over the next week you’ll probably need binoculars to see it, but it may brighten to become a naked eye comet later this month.

Here’s a star map showing where it will be in the sky over the next month:

cometpanSTARRSmap

 

This star map shows the view looking west just after sunset. The red crosses mark the path of the comet as it climbs in the sky, and the red numbers mark out the date in five day intervals, with 10 Mar being lowest on the map, then 15 Mar, 20 Mar, 25 Mar, 30 Mar, and finally 5 Apr. The horizontal line shows the horizon at 7pm in mid March, but the stars in this map will set earlier and earlier as we go into April. Put simply, you need to go and look west just as the sky begins to darken after sunset.

How best to see Comet PanSTARRS

There are a few tips to help you maximise your chances of seeing this comet:

1. Find an observing location with a clear western horizon (the west coast is ideal, but higher ground inland would be fine too).
2. Do your best to get away from very bright lights and out of city centres, where the horizon is normally built up anyway.
3. On 12 and 13 Mar the thin crescent Moon passes close to the comet, making it a little easier to find.
4. Don’t expect too much! The comet, even if it brightens as expected, will always appear low on the horizon, and in twilight, making it quite difficult to spot. Binoculars can really help you locate it.

Categories: Stargazing

iPhone Astrophotography: ‘magnifi’ iPhone case.

January 26, 2013 3 comments

This is a guest post by Andy Hewitt @andyuk71

I received a 6” reflecting telescope for Christmas – a Jessops’ TA900-114EQ. Blessed with clear skies and a glorious full moon, I focused the 20mm eyepiece and brought the moon in to sharp relief. Memories from my childhood came flooding back of a Prinz Astral ‘scope my father had bought my brothers and I, many Christmases ago, and I was thrilled to feel the same excitement I had had as a child. Naturally in today’s digital age, I wondered if it was possible to capture these wonderful pictures on my iPhone. I soon discovered that the iPhone is not naturally disposed to taking these kind of images, but a quick search on the net revealed that there’s quite a number of amateur astronomers out there obtaining passable results with them. The light-metering of the phone means that unless the phone is clamped in some way to the lens, unwanted light will leak in and decent results will be hard to get. Some kind of clamp arrangement would also possibly guarantee correct alignment between the phone’s lens and the eyepiece’s aperture. The image below was obtained by holding my phone to the telescope’s eyepiece.

Image

HR12.5mm lens.

A reasonable result after cropping and some tweaks in iPhoto, but the difficulty of aligning the lens with the eyepiece, coupled with the promise of even better results made my mind up to research if there was a better solution out there.

Image

Searching online, I found a couple of different options available in the form of cases, and decided to plump for the ‘magnifi’ (seen above), a Kickstarter project from the States that received enough backing to launch it into production. Not currently available direct from the UK, purchasing is easy enough via PayPal, though the mooted Custom’s charge was a suck it and see event… The device isn’t exactly cheap at £61.53, though I was prepared to take a risk, hoping the results would justify the expense. With international postage charges of £9.83, and an £8 Royal Mail handling charge, the grand total came to £79.36. It arrived in just under two weeks, as promised, and on opening, included everything listed on the website. The package comes with 4 rubber ring adapters to attach to your lenses to ensure a snug fit – in practice, this works without a hitch – and they fit very tightly to the lenses themselves; some people may find them a bit fiddly to put on, but no more than that. The case and lens attachment aren’t fitted together in transit, but again, this is really simple to do.

I took the first opportunity that came along to use the magnifi case, with the moon as my target object. It was at this point that certain realities became apparent. Firstly that the lenses supplied with my Jessops 6” reflector, are probably, erm, not the best thing about the telescope.

Image

As you can see in the picture, the barrels are short and the higher-powered the lens is, the less black plastic there is to clamp the magnifi to. Fortunately, the HR20mm is sufficient in this area and a good lens to view the moon with. The old moon in the new moon’s arms promised a lot with a terminator giving good contrast and cutting down the glare, but ultimately results were disappointing, and for a number of reasons.

Image

With the phone slotted into the magnifi case and the case clamped to the lens, a relatively large mass is added to your scope – at this point you get the measure of your mount. With the phone turned on to the camera app, it’s possible to view the moon via the phone’s screen and even bring in into focus. However, the fun starts when, after carefully aligning and framing your (moving) object, you press the button to take the picture and hey presto, you’ve introduced camera-shake. I tried numerous different strategies to overcome this issue with varying degrees of success. Undaunted, I moved my sights onto Jupiter and was rewarded through my telescope’s lens, by seeing the familiar bands of Jupiter with my own eyes – my first time – and rather unbelievably, the four visible-from-Earth moons (I think). I badly wanted to capture these images digitally, and did, but there was too big a gap in quality between what I was viewing through the eyepiece and what was being displayed on my phone, and ultimately being recorded.

Image

A frustrating interval of several cloudy night skies ensued then, but I was far more successful at my next attempt. Steve had pointed me in the direction of an iPhone app called SlowShutter and this proved to be a revelation. With a full moon to aim at on this occasion, I was determined to justify the expense I’d laid out. SlowShutter enables you to set the exposure time and also factor in a delay for shutter release. I set a 0.5 second exposure and a 5 second delay. After a bit of trial and error, dividends were soon in abundance and the gap between the eyepiece and iPhone was metaphorically narrowed.

Image

Full moon, HR20mm lens, some tweaks in iPhoto.

Some pros and cons. SlowShutter is a great app but, unlike the iPhone’s camera app, it doesn’t permit a digital zoom of the image in view – sometimes this is necessary to overcome the black circle effect that occurs with some lenses when using magnifi, dependent on their viewing aperture diameter. Depending on lens aperture size, the black circle can manifest in two ways, one you can zoom-in past, or one you can’t. I need to test this further though with some different/better eyepieces. Frustratingly, the barrels on my lenses are just physically too short to clamp magnifi to satisfactorily. I’m still very new to astronomy and astrophotography. I know barrels can be replaced or extended but I’m not entirely certain on how this affects the focal length of the lens.

Unless you have a rock-solid mount, pressing the button to take the picture will inevitably introduce blur to your image, which of course is the last thing you want, even the smallest movement is of course, magnified greatly: shutter delay overcomes this. Another problem is exposure. Images like the moon are very bright and play havoc with the light meter of the iPhone’s camera. However, I experimented with tapping on the screen in the light and dark areas, allowing the phone to re-meter and give a better exposure – SlowShutter has this facility too and even has an exposure lock feature, which aids between shots as normally the app would re-expose for the next shot.

Magnifi does allow you to take pretty decent images of what you’re seeing through your telescope, and as far as iPhone astrophotography contraptions go, it certainly offers a professional looking and well-made, thought-out practical option. It’s still early days for me and my use of magnifi. I live in a busy city with depressingly high levels of light pollution, so I’m limited to possible objects to capture. However, I envisage that with more experience, better lenses and of course, dark skies, the magnifi will prove to be an invaluable piece of equipment for me and other amateur astrophotgraphers.

Image below captured with HR12.5mm lens.Image

Categories: Astrophotography, Equipment, Stargazing Tags: , , , ,

iPhone Astrophotography: Night Modes

January 8, 2013 3 comments

As a follow-up to my previous post about astrophotography with an iPhone, I spent a few minutes tonight playing around with a new app called Night Modes, which claims to allow you to have real (hardware) shutter speeds of up to one second, a substantial improvement on previous apps which have used software tricks to try and mimic long exposures. These are next to useless for capturing star-scapes, photos of the night sky overhead. Even one second exposure is rather short, and will only let you catch the very brightest stars, but still more than enough to make out the constellation patterns.

Night modes allows you to set the exposure to 1/15, 1/8, 1/4, 1/2 or 1s, lets you deactivate the autofocus (which you’ll have to do – autofocus gets confused when you try and snap a picture of the night sky). The app also allows you to set a timer delay, to avoid hand-shake blurring your image as you push the button.

Another essential item to avoid camera shake is something you put your iPhone on when the exposure is being taken – ideally a tripod, but you can rest it on anything that won’t wobble too much. In the absence of a tripod adaptor for my iPhone I simply placed it on the table in my garden, propped against a book, pointing roughly towards Jupiter.

After setting a 5s delay (enough time, I reckoned, for me to place my iPhone gently on the table, and for any wobbles to die down), disabling auto-focus and auto-exposure, and setting the exposure to the maximum 1s, I sat the iPhone down and waited. And this is what I got:

IMG_6876

Orion, Taurus and Jupiter, taken with an iPhone 5 using Night Modes app, 1s, 3200 ISO

Not the best image ever, but you can make out Orion with those phone lines running in front, and in the top right corner you can see the bright (and slightly over-exposed) Jupiter above the V-shape of the head of Taurus. The next step will be to take some images out of the city, somewhere with less light pollution, so I don’t get that horrible orange glow to the sky.

Categories: Astrophotography, Equipment, Stargazing Tags: , , , , , ,

New Telescope for Christmas?

December 25, 2012 Leave a comment

Are you lucky enough to have been given a shiny new telescope for Christmas? If so you have joined the ranks of thousands of other stargazers around the world, and you’re no doubt eager to get outside and use your new toy.

But a new telescope can be quite a complicated and daunting piece of hardware, so let’s go through the basics, to help you on your way.

1. Read the instructions!
Like most complicated pieces of equipment your telescope should have a user manual or a set of instructions. If not, try looking online. These instructions will help you assemble your telescope, and become familiar with all of the various parts, including the finder scope, eyepieces, focus mechanism, and motion controls.

2. Align the finder scope in the daytime.
The small telescope that sits on the main tube of your telescope is called the finder scope. You can use this to locate an object in the sky, and if the finder- and main telescopes are aligned (facing in exactly the same direction) then that object will be in the centre of the field of view of your main scope too. Aligning the finder scope is a bit fiddly though, so do it in the daytime before you observe. Point your main telescope at a specific distant object, like a far away tree, or chimney pot, or transmitter mast. (WARNING: don’t point it anywhere near the Sun). Once that object’s in the very centre of your main scope field of view, look through your finder scope. The chances are it’s not in the crosshairs here, so adjust the position of your finder scope until it is. This is usually done using small screws that physically move the finder scope around till it’s aligned with the main scope. Now it’s ready to use tonight.

3. Pick the correct eyepieces.
Your scope probably came with a couple of eyepieces. These should be marked with their focal length, in mm. The higher this number the lower the magnification. So a 25mm eyepiece will provide smaller images than a 10mm eyepiece. But magnification isn’t everything. In most cases you should start with your least powerful eyepiece, which gives you the largest field of view. Once you’ve found your target you can substitute a more powerful eyepiece in, to get a larger image. It’ll be larger, but dimmer. After all you’re spreading the same amount of light over a larger image. You’ll also notice any wobbles in the telescope much more when you’re using a higher power eyepiece. So your low-power eyepiece will give you brighter, clearer images, even if they’re much smaller.

4. Learn how to move around the sky.
All telescopes are different, and the way that you move them from one object to the other varies. In general though they will all have hand-screws that you can tighten and loosen to lock the telescope in position, or to move it. There may also be dials or screws to give fine adjustments to a telescope’s positioning. On the other hand, some telescopes – called dobsonians – are just moved by physically nudging the telescope tube. However yours moves, you’ll be doing this in the dark, so practice, practice, practice until it’s second nature to you. Some motorised telescopes find and track the stars and planets for you, but these are a bit trickier to set up properly, so read the instructions.

5. Choose the right targets.
Don’t go hunting down very faint elusive objects on your first night out; stick to the brighter ones that are easier to find. On Christmas night and for a couple of days after, the Moon and Jupiter are up in the evening. Even a small telescope will give great views of the Moon (although you’ll get a better view when it’s not quite so full, and you can observe the line between light and dark, called the terminator line) and will let you see Jupiter’s moons, looking like four tiny specks next to the bright planet Jupiter.

Whatever you look at with your new telescope, enjoy it, and remember that patience is a virtue. You’re the proud owner of a great stargazing tool, but you need to practice to get the hang of using it properly.

Let everyone know what you’ve been observing, and how you’ve found your new telescope, in the comments below.

Categories: Equipment, Stargazing Tags: , , , , ,

Tau Ceti, a nearby Sun-like star, MAY have an Earth-like planet

December 19, 2012 Leave a comment

One of the closest Sun-like stars to us, Tau Ceti, in the constellation of Cetus the Sea Monster, MAY have a family of five Earth-like planets orbiting it, one of which MIGHT be in the star’s circumstellar habitable zone (CHZ), otherwise known as the “goldilocks zone” where it’s not too hot, not too cold, but just the right temperature for liquid water to exist.

Tau Ceti lies only 12 light years away from our solar system, which in astronomy terms is just next door. There are only 19 stars closer to the Sun, and only one of these is a Sun-like star, Alpha Centauri, which lies only 4.4 light years away.

Tau Ceti is a bit smaller than the Sun (0.8 times the Sun’s radius), is cooler (5350K compared to the Sun’s 5780K) and less luminous (0.5 times the Sun’s brightness), and so the CHZ in which the Earth-like planet MIGHT orbit is much closer to the star than the Sun’s CHZ, around half the Earth-Sun distance, approximately 75 million kilometres.

The five planets that MIGHT have been discovered are labelled Tau Ceti b, c, d, e, and f, and the Earth-like planet is the fourth from the star, e.

Why all the MAYBEs and MIGHTs? Well, that comes down to the method by which the planets were detected. They were discovered by observing the star Tau Ceti, and watching for wobbles caused by the gravitational pull of the orbiting planets. Now all five potential planets are similar in size to the Earth, between two and six times the mass of the Earth, but still are tiny compared to the star, and so the wobbles they cause the star to make are very small, almost indistinguishable from noise in the data. Further studies of the star’s wobble might show that some, none, or all of these potential planets might just be artifacts in the data.

How to find Tau Ceti in the sky

Tau Ceti is visible in the sky this month, lying low in the south around 8pm. To find it you have to star hop from the distinct constellations of Orion and Taurus to the much less obvious Cetus.

Find Orion, with the three stars of Orion’s belt pointing up and to the left to the bright star Aldebaran in Taurus. Aldebaran lies in a V-shape collection of stars called the Hyades making up Taurus’ head. This V-shape arrow points down and to the right to a bright-ish star called Menkar in Cetus, lying low in the south. Lower and to the right is the brightest star in Cetus, Diphda, and the fainter star to the left of this is Tau Ceti. Phew!

taucetimap

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

Morning Mercury, December 2012

December 2, 2012 1 comment

Over the next few mornings you’ll be able spot the most elusive of the naked-eye planets, Mercury, low in the south-east just before sunrise.

Mercury is hard to find, and most days isn’t visible at all. Since it orbits so close to the Sun, when seen from Earth it never appears very far from the Sun in the sky. You can only catch it for a few days at a time when it’s furthest from the Sun in our sky, at a point called its maximum elongation. And even then it’s not that simple to find, as it will always be quite low on the horizon, hidden amongst twilight.

As Mercury whizzes round the Sun (it takes 88 days to make one complete orbit) sometimes we see it in the morning and sometimes in the evening. The amount of time between one morning appearance and the following evening appearance is around six or seven weeks. However Mercury isn’t very clearly visible at every maximum elongation (in some the Sun is much nearer the horizon so the sky is much brighter, making it harder to find), and even when it is clearly visible you’ll only catch sight of it on the few days before and after the date of maximum elongation.

Mercury’s next maximum elongation in of 4 Dec 2012, when it’s quite far (21°) west of the Sun, and quite bright (magnitude -0.3) making it quite easy to spot over the next few mornings.

How to find Mercury

If you have clear skies, head outside around 0630 and find somewhere with a good clear SE horizon (Mercury rises around 0630 and only gets a few degrees above the horizon by the time the Sun’s light begins to significantly brighten the sky).

Luckily there are two other planets up near Mercury right now, namely Venus and Saturn. Both of these planets are brighter than Mercury and higher in the sky, and together all three form a straight line leading diagonally down to the horizon. Find brilliant Venus, the brightest thing in the sky except for the Sun or the Moon, and then look for Saturn up and to the right, and Mercury in the opposite direction, down and to the left.

This photo, taken by the excellent Paul Sutherland, shows how the three planets lined up this morning (2 Dec) when viewed from the UK.

Mercury, Venus and Saturn in the morning sky. Image credit Paul Sutherland.

Mercury, Venus and Saturn in the morning sky. Image credit Paul Sutherland.

Categories: Stargazing Tags: , , , , , , , , , ,
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