The Daily Parker

Politics, Weather, Photography, and the Dog

If it were clear, and dark, and there were no streetlights

...this app might be fun. CityLab explains:

Floating in space among the stars and planets are more than 2,250 satellites and “space junk” traveling at up to 18,000 miles an hour. Some are large enough to be seen with the naked eye—though you’d have to first figure out which ones are within your line of sight.

Luckily, there’s a map for that now, by Patricio Gonzalez Vivo, a graphics engineer at Mapzen who has a knack for turning pure data into mesmerizing visuals (like this one of New York City). His latest project, Line of Sight, traces the orbital path of more than a thousand of those satellites and predicts their current location using open-source data from tracking sites like CelesTrak andSatNogs. Plug in your address (or choose one of the pre-selected cities) to see if there are any satellites—shown as yellow dots—nearby. Or zoom out to watch all the satellites orbit the Earth at once in a dazzling visualization.

His city visualizer is also really cool.

Might have to get up early

A G3-class solar storm (i.e., a big one) is predicted to hit the earth tonight, generating category 7 aurorae, which are rarely seen on earth:

Auroral activity will be high(++). Weather permitting, highly active auroral displays will be visible overhead from Inuvik, Yellowknife, Rankin and Igaluit, to Portland OR, Cheyenne, Lincoln, Springfield, and New York City, and visible low on the horizon as far south as Carson City, Oklahoma City, and Raleigh.

Here's the prediction map from the University of Alaska at Fairbanks:

But here's the observed aurora right now:

So, while the aurora isn't yet visible in Chicago, the solar storm might propel enough material into our ionosphere that we could see some auroral displays in a few hours—or tomorrow. The prediction for Tuesday calls for displays overhead central Wisconsin which would be visible down to St. Louis, weather permitting.

The only place in Chicago dark enough to see them is the lakefront. Parker and I might have to walk over there tomorrow evening.

Updates as events warrant...

Changing the clocks

If you live in the parts of the U.S. and Canada that observe Daylight Saving Time, don't forget to move your clocks back an hour tonight. It couldn't come soon enough, though this is the soonest it can come under the 2007 changes to DST observance.

This morning's 7:22 sunrise in Chicago is the latest we'll have to endure until next November 1st, but tonight's 5:47 sunset is the latest we'll get to have until March 6th. Tomorrow the sun rises at 6:23 and sets at 4:45, as our available daylight shrinks from 10 hours, 24 minutes today down to 9 hours, 7 minutes on December 21st.

I'm not a fan of the 2007 changes. I like switching to DST in the spring and switching back in the fall, but I also believe that mid-October (or even the end of September as they do in Europe) makes a lot more sense. At least mornings aren't so gloomy in the fall. (Not a lot we can do about the post-7am sunrises from December 2nd through February 5th, but we expect those two months to be gloomy.)

Of course, I'm not in Chicago at the moment, and it's plenty sunny here...

Total eclipse of the moon

The weather in Chicago cleared up enough that we got a great view of the total lunar eclipse last night:

For comparison, here is the full moon when Earth doesn't get in the way:

Note that it's a lot harder to photograph the moon when it's eclipsed. The full moon reflects 9% of the light falling on it, or about half as much as a standard gray card or green grass. So when shooting the moon, the correct exposure is surprisingly fast: about 1/250 at f/5.6 at ISO 100. Shooting the eclipse last night, I used 1/10 at f/5.6 at ISO-25600. And a tripod.

Moon disappears; film at 11

OK, so, astronomers predicted tonight's lunar eclipse about 6,000 years ago, but it was still bloody cool. I'll have photos tomorrow. Meanwhile, I am happy the clouds over Chicago parted long enough that I could see one great rock cast a shadow on another. It happens every six months, I realize, but it won't be visible again in Chicago for many years.

Lunar eclipse weather forecast: excellent

WGN's Tom Skilling is optimistic about seeing Sunday night's eclipse:

While the first vestiges of Sunday evening’s full moon will begin at 7:40pm, the partial eclipse stage is to be reached at 8:07 pm Chicago time moving toward the “total eclipse” phase at 9:11pm. The disc of the moon will take on a dim rusty-red cast in the total eclipse phase for 1 hour and 12 minutes (through 10:23pm Sunday evening). The partial eclipse phase is to be reached at 11:27 pm and the eclipse ends at 11:55 pm.

The early read is that the weather is going to cooperate in viewing the event from Chicago and the Midwest. Here, from the National Weather Service’s GFS forecast model is a forecast of the likely location of cloud cover at differing heights–and, finally, a composite of potential total cloud cover at 7pm CDT Sunday.

Here is the GFS model’s total cloud cover prediction. Sunday is likely to be an unseasonably mild late September day with brisk southerly winds likely to boost daytime temps across the VChicago area to around 80-degrees and to limit nighttime lows to the 60s.

Here's hoping. It should be an epic eclipse.

Lunar eclipse + Harvest moon + perigee = cool

I hope Chicago has decent weather for the full moon 11 days from now:

It's coming Sept. 27 at 9:47 p.m. CDT.

For starters, it is what some astronomy enthusiasts call a "super" moon because it will occur when the moon is close to perigee, its nearest point to Earth in its elliptical orbit.

The moon reaches perigee Sept. 28, and it will be just more than 222,000 miles away at the time of the full moon. That is about 31,000 miles closer than lunar apogee, the moon's farthest point in its orbit.

The moon appears about 14 percent bigger and 30 percent brighter at perigee than it does at apogee, according to NASA. But it doesn't look dramatically different to the naked eye.

The full moon also comes with a full lunar eclipse, all of which will be visible from the eastern half of the United States, including Chicago. Such eclipses can give the moon a reddish tint, caused by light bending through Earth's atmosphere.

Here's the official NASA page showing just how disappointed we'll be if it's cloudy in Chicago.

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?