Fast cars! Drones! Astrophotography! The Thames!

One evening the skies miraculously cleared, so I took the camera with the biggest lens I've got and star tracker down to the local park. After the usual faff of aligning with Polaris, it was rotated to a suitable target and the camera set taking a couple hundred of shots.

That left a long time hanging around, looking at the stars, listening to traffic and dog walkers fail to control their pets.

Then there was this light, out on the Thames, slowly gliding up-river. It was followed by the familiar whine of a drone. So I left my camera doing its thing and rushed to the bank to see what was going on. 

I had time to snap the above, which didn't tell me much, apart from the need to go Google "Eletre", which I did. And up popped this video, which did indeed show a glowing box with Eletre on the side gliding up and down the Thames. It was the latest electric vehicle from Lotus:

Very cool!

It and the drone was last seen heading under Putney Bridge so I returned to my camera, and this was the resulting image:

An interesting evening

Sailing from Tangier to Rabat

After Tangier we headed south. There was enough wind to leave under sail, though it was rather weak and from the wrong direction. So in the end the engine was started and we motor-sailed down the coast of Morocco.

I was beginning to feel not great but was determined to do at least one night watch. There was a lovely sunset which brought pretty much everyone on deck:

There is a magic to being on a yacht offshore at night.

The night's sky is amazing - full of bright stars, the Milky Way clearly visible. Old friends like Orion, Ursa Major, Cassiopeia ... (and all the other ones I should really know), the North Star on its own, pointing home, a crescent moon and even a shooting star. I tried to remember the equation of the star clock, but failed.

We had to dodge a couple of fishing boats but the ones we saw had lights so that was pretty easy.

I wasn't sure how much of this offshore night-time sailing I'd be doing in the future so tried to capture the moment in my memories before heading down to my bunk...

The northern lights from deck

 As seen from the deck of Opal in Greenland.

The northern lights over Greenland

With Opal at anchor.

Three planets and the Cosmonauts

This morning I got up at 05:30 to do a spot of astronomy. It wasn't as bad as it sounds thanks to the hour change, so in BST it would be the more reasonable 06:30.

The light was rather beautiful and I had just a handful of early rising birds for company.

The reason for heading out into the cold was the conjunction in the morning eastern sky of Venus, Jupiter and Mars, making a clear and bright triangle:

There's a nice little gif identifying each and describing their motion to be found here.

There's more space in London at the moment with a superb exhibition of early Soviet / Russian space technology in "Cosmonauts" at the Science Museum:

It was all rather brilliant, with lots of fantastic real engineering, such as Valentina Tereshkova's Vostok 6 capsule. The only downside was KGB levels of scrutiny to ensure that no photos were taken - apparently there were items on display that had to be specially declassified.

Well worth looking up in the night's sky if you have a cloud-free morning or visiting the Cosmonauts if you're in London.

Eclipse on a grey day

Today there was a partial eclipse across the UK, and the weather didn't really help with cloud blanketing most of the country.

However last night the forecast was for there to be a patch of clear sky about an hour's train journey north of London so I took a chance on a train to Leicester.

Partial eclipses aren't that spectacular as it just gets a bit dim and you really mustn't look at the sun so all the action involves projecting images. I had a very ad-hoc arrangement of camera resting on a pair of binoculars, both pointing at a piece of white paper.

I arrived on time, to find the sun out enough to cast a shadow and in a near empty park took the above.

The one to look out for is in 2017 when a total eclipses crosses continental USA though probably the best observing sites and hotel rooms have already been snapped up.

Magical night with northern lights

For the last night at sea my watch was 9 pm until midnight and it was jolly cold. We'd got south enough for it to get dark, just below the Arctic Circle at 65.5N, and it was a clear, star filled night.

Now we were motoring the main duty on watch was keeping an eagle eye out for ice, and it wasn't easy. Ok, some big 'bergs were pretty obvious as they reflect like the White Cliffs of Dover:

Smaller bits are however harder to spot and some become translucent, vanishing into the waves. A couple of times we had to slow down to get through flows of bergy bits spored by an island of ice.

It was hard work and I was looking forward to my warm bunk when it was decided to keep going and do a second watch as we'd be anchoring soon.

We were rewarded for this effort by a mini-display of the northern lights (top pic) which rather remarkably were to the south of us, but that's Greenland for you. They only went for a few minutes but we'd definitely seen them.

It ended up being rather a magical night, a harsh beauty of stars, shooting stars, Iridium satellite flares and what looked to me like noctilucent clouds:

For the first time since Iceland we saw some flashing lights marking out a channel guiding us toward the narrow entrance into Tasiilaq fjord.

Then in the dim light of what was now early morning could make out the town, a jumble of coloured wooden houses clustered around a little hill:

The anchor went down with a splash and rattle of chain: we had arrived and I could head down to my bunk and rest.

Super Moon

Over the weekend there was the "super moon", which is when it is at perigee (i.e. closest to the Earth) and full at the same time, and I took the opportunity to take this photo.

Of course the moon appears to be up side down....

The star clock: deriving 41.5

Yesterday's post was about the sky clock you could use to work out the time by looking at the sky and knowing the month, and it was the equation (terms explained in previous post):

    LocalTime = 41.5 - 2 * (SkyTime + Month)

Tillerman asked the question why is the constant 41.5?

Good question - but I'm not an astronomer, and haven't done these calculations before, but then that is what Wikipedia is for so here goes.

Firstly lets rearrange the equation so the constant which we'll call K (we maths types like short variables) is on one side:

    K = LT + 2 * (ST + M)

We want is to derive are all the terms on the right and hence we can calculate K, but how?

So what do we know? Well lets start with the two stars Alpha Ursae Majoris and Beta Ursae Majoris, and Wikipedia gives their right ascension (RA) and declination. These are the astronomical equivalents of longitude and latitude respectively, and the RAs are very similar - which is what you'd expect for something that points at Polaris Its like two points with different latitude but the same longitude: you know that line is going to head up to the poles.

But how to match RA to longitude? Classically you'd use the equinox, when RA = long = 0 and the sun is due south from Greenwich, but that's no longer used as it doesn't include effects such as nutation, so now we need to consider J2000.

J2000 is the time reference used for most celestial mechanics applications and is referenced to 1st January 2000 at midday, 12:00 UT, or JD 2451545.0, and it is this frame that is used to define the RA of these two stars as around 11 hours.

To convert from RA to longitude we need the sidereal time equation:

   GMST = 18.697 374 558 + 24.065 709 824 419 08 * D

Here D is Julian Date and everything is in hours, which is great, as that's the units that all the terms in the equation are in.

If we find a date at which the GMST is zero then the RA will be the same as the longitude and the constellations should look similar to the graphic above. I used the iPad app Red Shift with observer at London and time set so that theta should be zero, hence the two stars should be at longitude 11 hours, or in degrees 165E.

In the graphic above the up arrow goes over one's head (standing in London looking north) and then down the longitude = 0 line to the Antarctic. Meanwhile the down arrow is the other side of the Earth, going down the international date line.

The date and time that GMST is around zero around the spring equinox - to be more precise, using the equation above, around 36 seconds after noon on the 21st of March 2013. With our back to front clock the leading lights of the Plough are at a time of 11/2 + 6 = 11.5

The divide by 2 is because the sky clock goes round 12 sky hours to 24 on Earth and the + 6 because the zero line at the top is sky clock 6:

Hmm.... the projection here makes it look like those two stars don't line up with Polaris, but of course that's just an illusion.

So we know (rounding a bit):

     ST = 11.5 hours

     LT = 12 hours

But what is the month? Is it:

    Month = 12 * Day / 365

That would be mathematically nice but not how non-maths types are likely to answer. If the month is March then the answer is 3, despite there being a 31 day range covered by a single integer.

To minimise error lets say that month = 3 is mid March, hence our reference date of 21st March is a little more than 3 - in fact Excel suggests 3.26 or so.

So we now know all three parameters and can plug them into our equation to work out the constant:

    K = 41.58142726

That's reassuring close to the number we were looking for (or at least it is to me - I know there will be some that are hoping it would be either 42 or 43).

Does that sound plausible?

The star clock

The World Cruising Club stand at the Boat Show had a short talk by Stokey Woodall on navigating by the stars, and having fond memories of the night's sky mid Atlantic boosted by reading Tristan's book on Natural Navigation, I went along for a prep.

Most of it was based upon spotting Polaris but there was one nice trick about how to use it and the Plough to work out your time.

Basically look at the night's sky and think of a back to front clock as in the graphic above, and then work out the "sky hour" of the leading edge of the Plough.

Then the time can be estimated using:
       Time = 41.5 - (2 * SkyHour + 2 * Month)

So if the sky hour is 7 at its April then the real time is:
      Time = 41.5 - (14 + 8) = 19.5 = 7.30 pm

Neat!

More detail in "The Natural Navigator" footnotes for the chapter on The Firmament.

Remembering Gagarin

In honour of the 50th anniversary of Gagarin's successful first orbital flight here's another picture of the moon (taken this time with small tripod).

The Aurora

The Aurora from Terje Sorgjerd on Vimeo.

For an explanation as to why this is the limit of my blogging at the moment, check out the most recent Dilbert.

Moon photo for Super Moon Day

Today is not just any full moon, its a super full moon!

Well to be precise it's a full moon when it is also at its perigee i.e. nearest point to the Earth, and hence is just slightly bigger than normal. It is not actually the nearest so don't fear Hollywood style destruction, as it will be closer still in 2016.

The above photo was taken yesterday when the moon was nearly but not quite exactly full. It's also not quite as sharp as I'd like and I'm wondering why. I tried getting the exposure time down to reduce motion blur, but that didn't help so I'm wondering if its a sign of weakness in the lens.

Its a rather cheap and cheerful 70 - 300 mm Canon lens, the bottom of their range, and with a new 18 megapixel camera that is likely to be the weakest point. So I have been checking out options on http://www.eflens.com/ and as always the best lenses are the most expensive and heavy, which is not helpful.

One question I'm not sure on is whether it would be better to go for a higher quality lens at 200 mm or a not quite so good lens at 300 mm - any suggestions? I really do not want anything too big or heavy - or silly expensive.

North heading West

Oh no! Another navigation post - surely its time to move on!

Well that's exactly what the North Magnetic Pole is doing. According to this article from the Independent it is heading towards Russia and speeding up as it does. It's now racing at about 60 km/year.

Hold on to your hat and do adjust your sets.

Rather appropriately currently watching right now in HD the latest Brian Cox TV series, the Wonders of the Universe, where have seen a brilliant description of entropy through use of a sand pile and castle (you'll just have to watch it) and hence explain why there is an arrow of time.

Of course there must be an arrow of time: how else could we - or rather he - say "Things can only get better"?

The truth is out there - Part 2

Ok more from JP's X Files.

The Natural Navigator spotted this object near Venus - full background here - and he's looking for help identifying it.

I'm going with a satellite, but it wasn't a point like object.

Anyway - what do you think?

The truth is out there

A couple of days ago I posted Buff Spaceman's report on the "Spontaneous Crystalline DHMO Alien Sculpture Phenomena" or SCDASP in which he went on to suggest a link between SCDASP with the North Star, saying it was "the focus on an ongoing investigation."

Imagine my surprise when I read on the interwebby thing that NASA, as part of the SETI project, transmitted a message towards Polaris!

Spooky or what.

More on the search for ET in a great BBC4 documentary about the Drake Equation to be found on iPlayer here.

I was going to post a link to the Natural Navigator's puzzle about the picture above (basically asking what's wrong with it) but was too busy so the answer has already been supplied, by, err, me.

Anyhow, head over there so you can say "I could have told you that!"

Then you will see how these two stories are connected.

Another Moon

Another clear night so another Moon photo. But this is no quick and easy post as there were many trials before took this one.

The moon is rising very far to the North at the moment - an explanation at the Natural Navigator site here, though to be honest I can't quite get my head around it so will email Tristan for more.

Shooting the Moon

In a post at the start of this year I showed my failed attempt at photographing the Moon. Using the default settings the exposure was ludicrously long, leaving the heavenly sphere little more than a white circle.

However knowing that this evening the Moon would be both visible and the skies clear I did a bit of Googling and came up with this great article on top tips, first of course to manually set the exposure.

And after a couple of cycles of go-out-get-cold-come-in-check-pic I ended up with the above, which is a lot better!

For those wanting technical details it was my venerable and soon to be replaced Canon 350D together with Sigma 70 - 300 mm lens, 400 ASA, 1/1250 sec exposure F/5.6.

Stunning Space

I could try and think up some connection between this pic and sailing (navigation maybe or that they come from the Royal Observatory in Greenwich?) but to be honest I'm posting it as its one of a series of just amazing photos of the night's sky.

They are the result of the 2010 Astronomy Photographer of the Year, and you can see a slide show of them together with audio description if you click here.

Silent Skies

London's skies are for once completely clear of aircraft. There's an almost eerie lack of sound as we miss the relentless roar of jets from above as the volcanic dust continues to spread

In the pic above there seems to be a smog like reddy band along the horizon where the sun has just set, which I guess is the culprit.

You can also see the sliver which is the new moon and the evening star, Venus.