Archive for the ‘Moon’ Category
As 2011 is drawing to a close, the festive season is here and many of us are winding down and looking forward to the holidays. But this is a great time to look ahead to 2012 and pencil into our calendar and diaries the top astronomical events we don’t want to miss next year.
2012 is going to be a great year for astronomy observing, with some rare and exciting things taking place and a good outlook with some of the regular annual events.
So what top wonders should we expect to see and what will 2012 bring? Read the rest of this entry »
Meteors streaking across the sky are an amazing sight. Every time I see a meteor is a thrilling moment.
I’m not a professional astronomer or even a specialized expert. I’ve just been watching the skies for meteors and showing others how to spot them for a long time. I particularly enjoy helping people who have never seen a meteor before experience their first sighting. My greatest success is watching the Perseid Meteor shower together with my kids while we were camping in the mountains together. It is an emotional memory that we’ll share all our lives.
Watching meteors is special because it truly takes no special equipment whatsoever. Telescopes or cameras just restrict your field of view – for best viewing simply lie back and enjoy the sky in front of your own eyes.
Meteorwatch itself is special for a lot of reasons. It is a world-wide event of professional and amateur astronomers getting together to share the heaven’s most showy display of the year. It’s an opportunity to collect real data that may be useful for astronomers to work with to increase our understanding of space. For me, meteorwatch is a chance to share my excitement with others who have never seen the beauty of a meteor flashing overhead.
Our goal for meteorwatch is to increase the odds for everyone to find meteors. Meteorwatch occurs August 12 through August 14 to correspond with the Perseid Meteor shower. The Perseids are a predictable shower that comes every year. In fact, meteors from the Perseids have been observed for about 2000 years already! The meteors are frequent and fairly bright, so it’s likely that you’ll be able to spot one if you go out prepared.
The first step of being prepared is that you need to find the darkest place you can find, as far away as possible from lights that will disrupt your night vision. If the moon is out while you’re observing, try to block it as best as you can with trees or a hill so you don’t look at it and ruin your night vision. If your night vision does get disrupted, you will not be able to see the dimmer meteors at all, so keep your eyes up and don’t pull out your phone to tweet every few minutes.
It’s true that Perseid meteors will likely come at between one and two meteors every minute, but you won’t be able to see that many because most of them are dim and washed out by city lights. The darker it is, the more meteors you will see! When I’m in a reasonably dark area near the outskirts of my city I’m happy to see one meteor every five minutes or so. If you can’t get out of the city, you may have to wait longer because you will only see the brightest meteors. There are plenty of sightings from the heart of cities, so it’s not impossible, just more difficult. It’s certainly worth an attempt if you can find a park without lights or some other dark area near you.
The second step is to make sure that you’re comfortable while waiting. A good chair that supports your neck while you look up is helpful. Even though the Perseids occur during summer, the nights can get quite chilly so dress warmly and bring something warm to drink.
The third step is to keep it an enjoyable outing. Some people like to go out alone and listen to music while waiting. That’s great too, but I usually tell first-timers to go out in groups. I especially encourage people to take their kids out. Young eyes may see phantom meteors at first, but once they get the hang of it they’ll spot meteors too dim for you or I to spot any more. Kids are fantastic at spotting meteors and it encourages them to be interested in the world around them. Besides, who wouldn’t appreciate a late night out once in a while?
The most frequent question I get asked year after year has been, “Where should I look in the sky to see the meteors?” In the past I’ve tried to describe how to find the constellation Perseus, but it’s rather unnecessary. Accustom your eyes to the dark, and after you’ve seen three or four meteors you should be able to figure out where Perseus is in the sky all on your own! It’s most important to look up, be relaxed and patient, and the meteors will dazzle in front of you as long as you are willing to watch.
Unfortunately, we don’t all get clear skies. Some of us are clouded out and have no chance at spotting meteors above us, but that doesn’t mean you’re out of luck. Follow the #meteorwatch hashtag on twitter for tips, pictures, radio observing and to share your experiences with other enthusiasts around the world. Go to www.meteorwatch.org for news and information and be sure to follow twitter.com/VirtualAstro for fantastic coverage of the Perseid Meteor shower direct from his Astrobunker.
Mark Zaugg is an amateur astronomer and enthusiast who particularly enjoys introducing people to the excitement of seeing a meteor in person. You can find him at twitter.com/Zarquil
A classic summer astronomical standby may be in trouble this year, but that shouldn’t stop you from looking. That’s right, we’re talking about the Perseids, that “old faithful” of meteor showers which sees northern hemisphere residents getting bundled up to camp out under the summer stars every mid-August.
Some of our earliest astronomical memories come from watching this very shower under the dark northern Maine skies of our 1970’s childhood… yes, the Perseids are public crowd-pleaser and even an occasional Yahoo-trending fave that can even knock the likes of Brittany & friends down to the number 2 slot for a 12 hour period… so, what’s this news of the Perseids being “troubled?” They haven’t been threatened by irate pop stars, have they?
Unfortunately, this year’s menace is a more inviolate force; the Full Moon. Yes, this year’s Perseid meteor shower peaks the morning of August 13th, mere hours before the Moon reaches Full status on the same day at 14:57EDT/18:57UTC. Instead of the usual respectable zenithal hourly rate (ZHR) of around 100 meteors per hour, observers can only expect to see a paltry few of the very brightest fireballs…
But all is not lost. With a little planning, a few factors can work in YOUR favor this year. Keep in mind that the Perseids have a very broad peak, and the radiant near the head of the constellation Perseus lies above the horizon all night for observers north of 32° latitude. Plus, this month’s Full Moon (known as a Sturgeon Moon) has a southerly declination of about -11° degrees; your best bet for catching Perseids this year may lie with watching several mornings prior, in the window of time between the setting of the waxing gibbous Moon and the beginning of local twilight… and yes, you CAN still watch a meteor shower during a Full Moon and see an occasional Perseid.
Generally speaking, the farther north in latitude you are located, the more likely you’ll be able to take advantage of these twin factors. Finding as dark a site as possible and putting something physically between yourself and the bright Moon is the key. A building or a hill makes an excellent “Moon-block.” Perseids are swift movers with an atmospheric entry velocity of about 61 km/sec.
The meteors are tiny grain-like debris shed by the comet Swift-Tuttle, and the shower occurs as the Earth intersects the path of the comet every mid-August. The Perseids are also famously known as the “Tears of Saint Lawrence” who was martyred on August 10th, and are probably the most well known of all meteor showers because of their annual dependability and their timely occurrence with the northern hemisphere summer vacation and holiday season.
Historic ZHR rates have always hovered around 60, but the past several years have seen an enhanced ZHR of +100. This shower is also infamous for sparking “Meteor Shower of the Millennium!” headlines annually, Although I have yet to see the same occur this year… a shower that MAY be a contender for said headline is the Giacobinids (or do you say Draconid?) meteors in early October 2011, an obscure shower that may dazzle this year… more on this to come in October.
Wonder what that the above graphic has to do with anything astronomical? You are looking at what is known as a nomogram, a graphical device that is a neat way to show interrelationships between factors. (Hey, how do you spend your weekend?) The graphic above was adapted from a nomogram featured in the November 2002 issue of Sky & Telescope; it shows the interrelationship between the two biggest factors that affect the zenithal hourly rate; namely, the radiant’s elevation above the horizon, and the limiting magnitude of your sky. (For a way “math-y-ier” dissertation on nomograms and the ZHR, click here).
This device will be your indispensible friend and secret weapon as you plot your meteor observing adventures for this or any shower. The ZHR is a theoretical limit; it assumes that you have absolutely perfect skies with a radiant directly overhead and an unwavering 360°degree view. Unrealistic, right? Well, it’s something to strive for. As you can see after playing around with the graphic a bit, the biggest killer of how many meteors you’ll see is how dark a sky you are under.
Even when the Perseid radiant is half way (45° degrees) in altitude towards the zenith, a limiting magnitude of +4 (as is typical around a Full Moon) means you’ll see roughly 10% of the zenithal hourly rate, i.e. 6-10 meteors per hour instead of 60-100. Yes, light pollution, both natural and manmade, is a real meteor shower buzz-kill. And keep in mind, other factors can conspire to lower that rate even further, such as obstructions on the horizon and the fact that a sole observer can only cover a limited swath of the sky visually. Still, the sight of a well placed fireball can be unforgettable and just plain pure magic to witness.
Do get out there on days leading up to this week’s Perseid meteors, and be sure to follow and report the magic via #meteorwatch on Twitter; they’re worth setting an early alarm for!
I am the dead albatross on your boat.
I am the peacock feather in the house.
I am horseshoe carelessly nailed upside down so all the good luck falls out down a grid.
If you ever see me coming to stand next to you at a star party, meteor shower, or eclipse, you have permission to make the cross sign with your fingers and run backwards as fast as you can.
That’s because, for my 33 and a half years of sky gazing, I have managed to cause cloudy skies and inclement weather at every single major event I have attended.
Just for the record, I’m a keen amateur astronomer without a telescope. I follow as many Twitter astro accounts as I can, avidly retweeting the latest data from Cassini, and following lonely Mars landers as they bump across rusty rocks. I cried the first time I saw the ISS, and as a child, I used to stand in the garden with a compass, straining hard to see the northern lights. I never did.
My bad luck began in earnest when I went to Cornwall for the eclipse. A boyfriend and I spent a small fortune hiring out a dank, uncomfortable cottage in the middle of nowhere. I was so excited that I woke up at 6.30am every morning, causing us to be grey faced and exhausted for the whole pitiful ‘holiday.’ And of course, on the big day, there was 100% cloud cover and it was so cold we had to wear gloves.
One night, me and the chap were out in Sefton Park, Liverpool, admiring a wonderful conjunction of several planets dancing around a new moon like fairy lights. Flushed with happiness, we went in and congratulated ourselves for figuring out how to use a planisphere. Next morning we were mortified to find out aurora had been visible ten minutes after we went in.
And indeed, only last week, I was photographing some incredible clouds where I live in Bristol, only to be told a short while later that even more aurora had decided to shimmy their way on to the sky’s stage while I had my back turned.
I travelled to America last year, and on my first night, I was so jetlagged that I shut the blind to keep out an incredibly bright moon. Mr Moon was very cross at my ignorance, and proceeded to turn bright red with rage, causing me to miss a spectacular lunar eclipse.
But the thing I have had the LEAST luck with…is meteor showers. I have stood out in back gardens and dark fields trying to catch a glimpse of these fleeting sky streaks at least three times a year from the age of 15. And guess what? Except for ONE Leonid I saw, cutting through soupy orange cloud two years ago, I have not had ANY luck. Truly disheartening.
That is, if you forget about last year. I was in Portland, on the west coast of America. Through a set of remarkable coincidences, which really do make me wonder if we are being pulled through our lives by twinkling cosmic threads, I ended up meeting some wonderful people who shared my love of all things that require tipping your chin up to 90 degrees to observe.
They took me out to a pitch-black nature reserve, bundled up with blankets and deckchairs, as bullfrogs boomed in the blackness, and baby racoons cavorted in the undergrowth.
On that magical, starry, starry night, we counted several hundred Perseids, each one causing me to gasp and grip the arm of my chair. One of the most memorable experiences of my life and one I long to repeat.
So. Will I be turning my head skywards for the Perseids this year? Of course I will. But judging from past form, I’d say, chances are, Bristol is not going to enjoy clear skies. I just seem to have that unfortunate effect on the sky over my head.
So if there are any astronomers in the Bristol area hoping for a good viewing, you may want to drive me out of town with planks and pitchforks. Either that, or take a trip to Inverness.
Follow me for further antics on twitter, I am @RadioVicky
These sites are ideal for all kinds of stargazing any time of the year and are set in some of the most beautiful locations in the country
The seven best National Trust sites for star gazing and see the wonders of the night sky are:
- Black Down in Sussex – Get closer to the stars on the highest point in the South Downs, just over a mile from the town of Haslemere.
Download the guide for Black Down
- Teign Valley in Devon – Discover the stars at this Trust property within Dartmoor National Park and close to Castle Drogo.
Download the guide for Teign Valley
- Penbryn Beach in Wales – Beautiful, unspoilt mile-long beach on the Ceredigion coast in west Wales, great for a bit of star gazing and a late night paddle.
Download the guide for Penbryn Beach
- Stonehenge Landscape in Wiltshire – Step back in time and discover the ancient skies of Salisbury Plain’s chalk downlands, home to the impressive prehistoric stone monument.
Download the guide for Stonehenge Landscape
- Wicken Fen National Nature Reserve in Cambridgeshire – Close to historic Ely, the wild landscape of the National Trust’s oldest nature reserve offers dark skies and a wealth of nocturnal wildlife to listen out for.
Download the guide for Wicken Fen
- Mam Tor in Derbyshire – Escape the bright city lights of Sheffield and experience the peace and tranquillity of Mam Tor’s dark skies in the Peak District.
Download the guide for Mam Tor
- Friar’s Crag in Cumbria – Surrounded by the breathtakingly beautiful scenery of the Lake District, Friar’s Crag in Keswick juts out into the spectacular lake of Derwentwater; a restful place to contemplate the world above us.
Download the guide for Friar’s Crag
More information about all of these sites is available by visiting: http://www.nationaltrust.org.uk/darkskies and enjoy stargazing and meteorwatch at these fabulous locations.
Thursday 11th to Sunday 14th of August 2011
From Thursday 11th to Saturday 13th of August 2011 @VirtualAstro on Twitter with the help of The National Trust, Universe Today, Royal Astronomical Society and many more, will be holding a Twitter Meteorwatch for the Perseid Meteor Shower.
Everyone is welcome to join in, whether they are an astronomer, have a slight interest in the night sky or just wonder?
As well as looking up, enjoying the night sky with us and seeing meteors, maybe for the first time? You will have the opportunity to contribute for fun with images and online, or to Science if you wish, by tweeting and seeing your results on a map, or by submitting Observing Forms if you are a more serious observer.
This event follows on from the popular Twitter Meteorwatch held in August and December of 2009 and 2010 “Meteorwatch 2009”
Use the hash tag: #Meteorwatch and get involved, ask questions, do some science, follow the event and enjoy the wonders of the night sky with us. Images and other information will be tweeted as it happens. Live!
Join in on Twitter, Facebook and Google+
The highlight of the summer meteor showers: The Perseids reach maximum around the 12th/ 13th of August and may put on a display of approximately 80 to 100 meteors per hour under ideal viewing conditions.
Conditions this year aren’t ideal due to there being a full moon, but the brighter meteors will be seen. Let’s hope the skies stay clear.
Perseid meteors are often bright with persistent trails which can linger for a while after the meteor has burned up. Further information on the Perseid meteor shower and how to view it, can be found here.
While you are looking for meteors, there will be other objects to look out for such as the Planet Jupiter late in the evening, the Milky Way, Summer Triangle, manmade Satellites and more.
The Twitter Meteorwatch will start at 21.00 BST on the 11th of August and will continue through to the evening of the 13th. Amateur and professional astronomers and stargazers from the US and other countries are invited to join in and take over from the UK, when the sun comes up here, helping make the event run continuously and be truly international.
Watch the awesome new trailer here….
Tonight (actually around 0130 tomorrow morning) the Full Moon will reach its highest point due south, just an hour and a half after the eclipse ends. Despite being at its highest in the sky, you’ll still struggle to see it, as it is very low down. In fact the Full Moon nearest the Summer Solstice is the lowest Full Moon of the Year
First, let’s begin with the definition of “Full Moon”. A Full Moon occurs when the Moon is diametrically opposite the Sun, as seen from the Earth. In this configuration, the entire lit hemisphere of the Moon’s surface is visible from Earth, which is what makes it “Full”. There is an actual instant of the exactly Full Moon, that is the exact instant that the Moon is directly opposite the Sun. Therefore when you see timings listed for the Full Moon they will usually include the exact time (hh:mm) that the Moon is 180° round from the Sun (we call this point opposition). Here’s a list of the times of all Full Moons between June 2011 and June 2012:
|Month||Date of Full Moon||Time of Full Moon (UT)|
|June 2011||15 June||2014*|
|July 2011||15 July||0640*|
|August 2011||13 August||1857*|
|September 2011||12 September||0927*|
|October 2011||12 October||0206*|
|November 2011||10 November||2016|
|December 2011||10 December||1436|
|January 2012||09 January||0730|
|February 2012||07 February||2154|
|March 2012||08 March||0939|
|April 2012||06 April||1919*|
|May 2012||06 May||0335*|
|June 2012||04 June||1112*|
* UK observers should add on one hour for BST As you can see from this table, the instant of the Full Moon can occur at any time of day, even in the daytime when the Moon is below the horizon. So most often when we see a “Full Moon” in the sky it is not exactly full, it is a little bit less than full, being a few hours ahead or behind the instant of the Full Moon. I’ll refer to this with “” marks, to distinguish this from the instant of the Full Moon (they look virtually identical in the sky). The Moon rises and sets, like the Sun does, rising towards the east and setting towards the west, reaching its highest point due south around midnight (although not exactly at midnight, just like the Sun does not usually reach its highest point exactly at noon). And like with the Sun the maximum distance above the horizon of the “Full Moon” varies over the year. The Sun is at its highest due south around noon on the Summer Solstice (20 or 21 June) and at its lowest due south around noon on the Winter Solstice (21 or 22 Dec) (of course the Sun is often lower than this, as it rises and sets, but we’re talking here about the lowest high point at mid-day, i.e. the day of the year in which, when the Sun is at its highest point that day, that height is lowest…) And because Full Moons occur when the Moon is directly opposite the Sun, you can imagine the Moon and Sun as sitting on either sides of a celestial see-saw: on the day when the Sun is highest in the middle of the day (in Summer), the Moon is at its lowest high point at midnight; and on the day when the Sun is at its lowest high point in the middle of the day (in Winter), the Moon is at its highest high point at midnight. This means, in practical terms, that Summer “Full Moons” are always very low on the horizon, while Winter “Full Moons” can be very high overhead. Here’s a table of the altitude of the “Full Moon” when due south. Remember the times in this table don’t match the exact time of the Full Moon, but instead have been chosen as the closest in time to that instant, and so have be labelled “Full Moon” (in quotes).
|Month||Date of Full Moon||Time of Full Moon (UT)||Time/Date of “Full Moon” due S||Time from/since instant of Full Moon||Altitude due S (degrees)**|
|June 2011||15 June||2014*||0127BST 16 June 2011||+4h13m||10° 05′|
|July 2011||15 July||0640*||0012BST 15 July 2011||-7h28m||10° 24′|
|August 2011||13 August||1857*||0126BST 14 August 2011||+5h27m||19° 19′|
|September 2011||12 September||0927*||0049BST 12 September 2011||-9h38m||31° 49′|
|October 2011||12 October||0206*||0053BST 12 October 2011||-1h13m||44° 16′|
|November 2011||10 November||2016||0005GMT 11 November 2011||-3h49m||53° 24′|
|December 2011||10 December||1436||0030GMT 11 December 2011||+9h54m||56° 03′|
|January 2012||09 January||0730||0006GMT 09 January 2012||-7h24m||53° 36′|
|February 2012||07 February||2154||0031GMT 08 February 2012||+2h37m||43° 47′|
|March 2012||08 March||0939||0000GMT 08 March 2012||-9h39m||35° 37′|
|April 2012||06 April||1919*||0145BST 07 April 2012||+5h26m||21° 45′|
|May 2012||06 May||0335*||0102BST 06 May 2012||-3h33m||15° 20′|
|June 2012||04 June||1112*||0047BST 04 June 2012||-11h25m||11° 49′|
* UK observers should add on one hour for BST ** The altitude here is based on my observing location in Glasgow, Scotland. You can find out how to work out how high these altitudes are here. As you can see from this table, the highest “Full Moon” due S this year occurs at 0030 on 11 December 2011, when the Moon will be over 56° above the southern horizon (approximately the height of the midsummer mid-day Sun which culminates at 57°34′). Compare this to the “Full Moon” this month, just after the eclipse, in the morning of 16 June, when the Moon barely grazes 10° above the horizon, and you can see just how low the midsummer Full Moon can be. In fact the closeness of summer “Full Moons” to the horizon means that this is an ideal time of year to try and observe the Moon Illusion.
The first total eclipse of the Moon of 2011 occurs this Wednesday evening, 15 June 2011, and it will be the longest lunar eclipse in over a decade. However the views from the UK (and Europe) will be constrained by the fact that the Moon will be below the horizon for much of the eclipse, and will rise fully eclipsed, or in some cases even coming out of eclipse. It’s still worth having a look though: just try to find somewhere with a very low and clear SE horizon, as this will be the direction in which the Moon will rise, and it will be in eclipse only while it is VERY low (only a few degrees above the horizon).
A lunar eclipse occurs when the Moon, in its orbit around the Earth, passes into the Earth’s shadow, as cast by the Sun. You might imagine that this would happen once every lunar orbit, or once a month. That it does not is due to the fact that the Moon’s orbit around the Earth is tilted by around 5 degrees compared with the Earth’s orbit around the Sun. So in most orbits the Moon passes above or below the Earth’s shadow.
Please read the rest of this article on Dark Sky Diary
I’ll make a prediction: on or around 19 March, when the so-called “Supermoon” occurs, at its closest approach to Earth in two decades, people will indeed report that the Moon looks much bigger than normal. But it won’t really be much bigger in the sky at all. It’s all in our heads!
You’ve probably all seen it before, a huge Full Moon sitting on the horizon. Time and again I have had people ask me why the Moon is so much bigger some times than others, and the answer is: it isn’t, really.
The Moon orbits the Earth in an elliptical orbit, meaning that it is not always the same distance from the Earth. The closest the Moon ever gets to Earth (called apogee) is 364,000km, and the furthest is ever gets (perigee) is around 406,000km (these figures vary, and in fact this Full Moon on 19 March 2011 will see a slightly closer approach of 357,000km).
So the percentage difference in distance between the average perigee and the average apogee is ~10%. That is, if the Full Moon occurs at perigee it can be up to 10% closer (and therefore larger) than if it occurred at apogee.
This is quite a significant difference, and so it is worth pointing out that the Moon does appear to be different sizes at different times throughout the year.
But that’s NOT what causes the Moon to look huge on the horizon. Such a measly 10% difference in size cannot account for the fact that people describe the Moon as “huge” when they see it low on the horizon.
What’s really causing the Moon to look huge on such occasions is the circuitry in your brain. It’s an optical illusion, so well known that it has its own name: the Moon Illusion.
If you measure the angular size of the Full Moon in the sky it varies between 36 arc minutes (0.6 degrees) at perigee, and 30 arc minutes (0.5 degrees) at apogee, but this difference will occur within a number of lunar orbits (months), not over the course of the night as the Moon rises. In fact if you measure the angular size of the Full Moon just after it rises, when it’s near the horizon, and then again hours later once it’s high in the sky, these two numbers are identical: it doesn’t change size at all.
So why does your brain think it has? There’s no clear consensus on this, but the two most reasonable explanations are as follows:
1. When the Moon is low on the horizon there are lots of objects (hills, houses, trees etc) against which you can compare its size. When it’s high in the sky it’s there in isolation. This might create something akin to the Ebbinghaus Illusion, where identically sized objects appear to be different sizes when placed in different surroundings.
2. When seen against nearer foreground objects which we know to be far away from us, our brain thinks something like this: “wow, that Moon is even further than those trees, and they’re really far away. And despite how far away it is, it still looks pretty big. That must mean the Moon is huge!”.
These two factors combine to fool our brains into “seeing” a larger Moon when it’s near the horizon compared with when its overhead, even when our eyes – and our instruments – see it as exactly the same size.
There seems to be a growing excitement about the “Supermoon” that is due to occur on 19 March 2011, when the Moon will be at its closest to Earth in this orbit, and closer than it has been at any time since 1992.
The Moon orbits the Earth in an elliptical orbit, i.e. it is not perfectly circular, and so in each orbit there is a closest approach, called “perigee” and a furthest approach, called “apogee”.
At this month’s perigee the Moon will be 356,577km away from Earth, and will indeed be at its closest in almost 20 years. But how close is it compared with other perigees?
Let’s start by comparing it to the Moon’s average distance from the Earth, which is ~385,000km. This perigee will be ~8% closer to the Earth than average. OK, that’s a bit closer, but not significantly so.
What about comparing it to the Moon’s average perigee distance, which is ~364,000km. So this “Supermoon” will be ~2% closer to the Earth than it is most months at perigee. Wow!
So what will this mean to you? Nothing at all. The Moon will be a few percent bigger in the sky, but your eye won’t really be able to tell the difference. It will also be a few percent brighter, but your eye will compensate for this too, so altogether this “Supermoon” will look exactly the same as it always does when it’s full.
As to all of those soothsayers claiming that there will be earthquakes and tidal waves. There very well might be, but they’ll be nothing at all to do with the Moon.
UPDATE: I predict that lots of people will report having seen a huge Moon on or around 19 March