The Daily Parker

Politics, Weather, Photography, and the Dog

End of the summer

Today is the Summer Bank Holiday in the UK, which has the same cultural resonance to the British that Labor Day has to us. It marks the psychological end of summer over. August 31st also marks the end of meteorological summer in the northern hemisphere. Over the next month in Chicago we'll see days shrink by almost two hours and temperatures fall by almost 6°C.

I hope, also, that by the beginning of winter, The Daily Parker will have a new home and infrastructure, and the ENSO will have pushed the storm track north of us to ensure a warmer-than-average winter.

The Prime Meridian isn't where you think

Via IFLS, the Independent reported yesterday that the Prime Meridian is not at 0°W:

Every year, hundreds of thousands of tourists from all over the world descend on the Royal Observatory in Greenwich to pose for a photograph astride the Prime Meridian, the famous line which divides the eastern and western hemispheres of the earth.

There is just one problem: according to modern GPS systems, the line actually lies more than 100 metres to the east, cutting across a nondescript footpath in Greenwich Park near a litter bin. Now scientists have explained why – and it all comes down to advances in technology.

According to a newly published paper on the discrepancy, which has existed for many years, tourists who visit the observatory at Greenwich often discover that they “must walk east approximately 102 meters before their satellite navigation receivers indicate zero longitude”.

I've visited the Royal Greenwich Observatory a couple of times, first in 2001. This sign was inaccurate then, but most people didn't realize it:

If you look at that photo's metadata, you can see the GPS location that I added using the mapping feature of Adobe Lightroom. According to Google Maps, the monument is actually at 0°0'5"W.

But the Prime Meridian was always primarily a reference point for time, not space, and therefore is exactly in the right place. As a commenter on the IFLS post pointed out:

The article uses the term "wrong" when in actuality Greenwich Mean Time (GMT) is still based on the Prime Meridian, though with the network of atomic clocks it isn't used much anymore, however the marker itself is very much in the right place. It is just when you use the coordinates on a GPS you end up at a different location. This is because GPS doesn't use the Prime Meridian as a starting point. GPS uses multiple locations all across the globe as anchor points in which to triangulate a location from called the geodetic system. The system does not rely on fixed straight lines as we see on a map but rather contours to the physical and gravitational shape of the Earth. So in essence just as the gig line (navy term) of my shirt doesn't lie straight and flat across by oversized 50 year old belly neither does the imaginary geodetic lines. These imaginary lines if drawn on a map would deviate east and west and would appear wavy. In the end, it is not about being wrong (as the article implies) but rather why do the two systems not match up.

(See? Sometimes comments on the Internet are reasoned and mostly correct.)

And this is science, too. As the Royal Observatory's public astronomer Dr Marek Kukula told the Independent, “We’re forever telling this story, making the point that as we refine our measurements and get better technology of course these things change, because we want to have the best possible data."

As a bonus, here's a photo from my most recent visit, in 2009. Look at all the tourists lining up on the 5-seconds-west line:

You can see my house from here

NASA released a really cool video yesterday:

The agency explains:

The images were captured by NASA’s Earth Polychromatic Imaging Camera (EPIC), a four megapixel CCD camera and telescope on the DSCOVR satellite orbiting 1 million miles from Earth. From its position between the sun and Earth, DSCOVR conducts its primary mission of real-time solar wind monitoring for the National Oceanic and Atmospheric Administration (NOAA).

EPIC maintains a constant view of the fully illuminated Earth as it rotates, providing scientific observations of ozone, vegetation, cloud height and aerosols in the atmosphere. Once EPIC begins regular observations next month, the camera will provide a series of Earth images allowing study of daily variations over the entire globe. About twice a year the camera will capture the moon and Earth together as the orbit of DSCOVR crosses the orbital plane of the moon.

These images were taken between 3:50 p.m. and 8:45 p.m. EDT on July 16, showing the moon moving over the Pacific Ocean near North America. The North Pole is in the upper left corner of the image, reflecting the orbital tilt of Earth from the vantage point of the spacecraft.

I love living in the future; don't you?

Pluto tomorrow

New Horizons zips past Pluto in the early hours of the morning U.S. time tomorrow:

Last night at 11:23 p.m. EDT (this morning at 4:23 a.m. BST), New Horizons moved within one million miles (1.6 million kilometers) of Pluto, speeding towards the dwarf planet and its five moons at 30,800 mph (49,600 km/h). It will arrive tomorrow at 7:49 a.m. EDT (12:49 pm BST), although owing to the vast distances involved and a one-way communications time of 4.5 hours, we won’t know if it has been successful until the end of the day. The first signals and data are expected back at 8:53 p.m. EDT Tuesday (1:53 a.m. BST Wednesday).

Despite the long journey time, the flyby will last just over two hours. The best images can be expected on Wednesday, but it will take 16 months for all of the data taken by the spacecraft to be sent back to Earth. This is due to both the distance and the low bit rate of the spacecraft, which has the ashes of its discoverer Clyde Tombaugh on board.

The spacecraft is the fastest-moving human-made object in the universe. This is how it got to Pluto in only 9 years, with the trade-off that its visit will be so short.

Scanning for life-forms...

Astronomers have discovered compelling evidence of alien life on the comet 67P/Churyumov-Gerasimenko:

Evidence of alien life is "unequivocal" on the comet carrying the Philae probe through space, two leading astronomers have said.

[Astrobiologist] Chandra Wickramasinghe said: "What we're saying is that data coming from the comet seems to unequivocally, in my opinion, point to micro-organisms being involved in the formation of the icy structures, the preponderance of aromatic hydrocarbons, and the very dark surface.

"These are not easily explained in terms of pre-biotic chemistry.

"The dark material is being constantly replenished as it is boiled off by heat from the Sun. Something must be doing that at a fairly prolific rate."

Welcome to the future.

Chicago sunrise chart, 2015-2016

Here's the semi-annual Chicago sunrise chart . (You can get one for your own location at http://www.wx-now.com/Sunrise/SunriseChart.aspx .)

Date Significance Sunrise Sunset Daylight
2015
2 Jul 8:30pm sunset 05:20 20:30 15:09
16 Jul 5:30am sunrise 05:30 20:24 14:54
9 Aug 8pm sunset 05:53 20:00 14:07
16 Aug 6am sunrise 06:00 19:50 13:50
29 Aug 7:30pm sunset 06:13 19:30 13:16
14 Sep 6:30am sunrise 06:30 19:03 12:32
16 Sep 7pm sunset 06:32 18:59 12:27
23 Sep Equinox , 03:21 CDT 06:39 18:47 12:10
26 Sep 12-hour day 06:42 18:42 11:59
3 Oct 6:30pm sunset 06:50 18:30 11:39
12 Oct 7am sunrise 07:00 18:15 11:15
22 Oct 6pm sunset 07:11 17:59 10:48
31 Oct Latest sunrise until 1 Nov 2016
Latest sunset until Mar 6th
07:22 17:47 10:24
1 Nov Standard time returns
Earliest sunrise until Mar 2nd
06:23 16:46 10:22
7 Nov 6:30 sunrise 06:31 16:38 10:07
15 Nov 4:30pm sunset 06:40 16:30 9:49
2 Dec 7am sunrise 07:00 16:21 9:20
8 Dec Earliest sunset of the year 07:06 16:20 9:14
21 Dec Solstice , 22:48 CST 07:15 16:23 9:07
2016
4 Jan Latest sunrise until Oct 28th 07:19 16:33 9:13
28 Jan 5pm sunset 07:08 17:01 9:52
5 Feb 7am sunrise 07:00 17:11 10:10
20 Feb 5:30pm sunset 06:40 17:30 10:49
27 Feb 6:30am sunrise 06:30 17:39 11:08
12 Mar Earliest sunrise until Apr 17th
Earliest sunset until Oct 24th
06:07 17:55 11:47
13 Mar Daylight saving time begins
Latest sunrise until Oct 16th
Earliest sunset until Sep 18th
07:05 18:56 11:50
16 Mar 7am sunrise, 7pm sunset
12-hour day
07:00 19:00 11:59
19 Mar Equinox 23:30 CDT 06:54 19:03 12:08
3 Apr 6:30am sunrise (again) 06:30 19:20 12:50
12 Apr 7:30pm sunset 06:15 19:30 13:15
22 Apr 6am sunrise 05:59 19:41 13:41
10 May 8pm sunset 05:35 20:00 14:24
15 May 5:30am sunrise 05:30 20:05 14:35
14 Jun Earliest sunrise of the year 05:15 20:28 15:13
20 Jun Solstice 17:34 CDT
8:30pm sunset
05:16 20:30 15:14
26 Jun Latest sunset of the year 05:17 20:31 15:13

You can get sunrise information for your location at wx-now.com.

Today is the longest day of the year

No, really. Today will have 86,401 seconds in it, as opposed to the usual 86,400 seconds that every day for the last 18 years has had.

Because the earth interacts with lots of other gravity sources in the universe—most notably the moon—its rotation sometimes speeds up and sometimes slows down. Over the last 18 years or so, the planet has lost an entire second because of these perturbations, requiring us to update our most accurate clocks to compensate. Of course, when those clocks get updated, there's a trickle-down effect, because so much of what we do in the 21st Century requires really, really accurate timekeeping.

So, this evening in Chicago, the 6pm hour will have 3,601 seconds in it as the master clocks all over the planet add their leap second at 23:59:60 UTC.

Enjoy your extra second.

Where's the weekend?

Between unpacking, preparing for a party (which encourages the unpacking), and the regular business of working, I didn't have time to write this weekend. I still don't, but I did want to catch up on a couple of things.

First, a coronal mass ejection over the weekend is producing large aurorae today, which could be visible in Chicago, New York, Dublin, and Seattle—way farther south than usual.

Second, Rhianna Pratchett, Sir Terry's daughter, says the next Discworld novel will be the last:

The author, videogame and comics writer told a fan last week that her late father’s forthcoming novel, The Shepherd’s Crown, featuring teenage witch Tiffany Aching, would be the final Discworld book. And asked by a fan if she would be continuing the series herself, she ruled out the possibility.

“No. I’ll work on adaptations, spin-offs, maybe tie-ins, but the books are sacred to dad,” she wrote on Twitter. “That’s it. Discworld is his legacy. I shall make my own.”

She added: “To reiterate – no I don’t intend on writing more Discworld novels, or giving anyone else permission to do so.”

Good for her. As blogger A.J. O'Connell wrote today, "Forty-one stand-alone novels are an amazing gift to give a fanbase, and I feel like it would be greedy to ask for more."

More later. Back to a deck that's due this afternoon.