I had the opportunity to present the monthly What's Up in the Sky at the March 10 Orange County Astronomers meeting. I'm sharing a sequence of images and animation that I used to illustrate the zodiacal light and the tilt of the ecliptic.
A high angled ecliptic greets us in the evening, and a low one in morning, making the evening planets easier to see by being farther above the horizon:
So, an observer at 30 degrees north latitude sees this: The planets and zodiacal light are high.
I had an opportunity to photograph Orion last night in two locations. One was in front of my home, and the other, out of town, just a few miles west next to an ecological reserve. Both locations have light pollution, but the reserve is as good as anyone can hope for in a region with many cities.
I was able to overlay my two photos without rotating or distorting either photo. Here there are in one animated graphic:
I'm presented a What's Up in the Sky for the Orange County Astronomers on 13 January 2017, and here I'm sharing some photos and images I created for the presentation.
"Klaatu Barada Nikto"
This time of year offers excellent orographic clouds,
such as this lenticular cloud over Mt. San Jacinto.
First is a comparison of the size of our sun as it appears now, in January, and as it will appear in July.
The larger outline in the photo is the sun from January 3, when Earth is closest to the sun. This photo was overlaid on a photo from July, when the Earth is farther away. There's a noticeable difference in size.
Below is an exaggeration of the orbit and the orientation of Earth's pole. Perihelion and northern hemisphere winter is on the left; aphelion and northern hemisphere summer is on the left.
The Earth's tilt defines the orientation of the seasons, which I've added as a ring with zones based on which season the Earth is in during its orbit. Because of the elliptical orbit, Earth accelerates as it approaches perihelion and slows at aphelion. So, the Earth is closer to the sun at aphelion, but it also spend less time in this position. The reverse occurs in northern summer. Our Earth lingers in the summer position because it slows near aphelion.
Many people are aware of the sun being closer and farther away while not being aware that earth is speeding up and slowing down.
The longer winter for the southern hemisphere was an early hypothesis for why Antarctica is so cold.
Astrologers like to point to the sun's position and imagine it has some influence in our lives. I like to point to the sun's position and say it has some real scientific relevance. In this case, the astronomer's understanding of Earth's changing orbit is a foundation of the science of climatology.
This understanding has linked the motions of Earth's tilt with the changing shape and orientation of the Earth's orbit with the rise and fall of Earth's ice ages.
As the Earth's pole precesses, our seasons rotate:
While the pole is precessing, the points of perihelion and aphelion are moving in the opposite direction.
Astronomers refer to the rotation of the season as precession, which as has a cycle of almost 26,000 years. Climatologist are interested in a different cycle that combines the motion of the seasons with the motion of perihelion. They also call this "precession" and recognize a cycle that varies in length between 19,000 and 23,000 years.
Climbing to Venus. Below is a recent photo of Venus of Intersection Rock at Joshua Tree National Park. The exposure brings out the lights from climbers scaling the rock at dusk. Projecting their path along a rock points to Venus, a worthy goal.
I propose that Astronomy can help. It can calculate the best time for attempting a climb to Venus. Let's look at our planets.
We have 4 planets visible in the western sky at dusk..
Our Evening Planets
Of these, Mars and Venus will show significant movement against the background stars.
Venus, moving the most, will come closer to Earth and change in apparent size. Now is a good time to watch and photograph Venus, aided by the high tilt of the ecliptic at this time of year. This photo shows relative sizes of Mars, Venus now, and Venus in one month if you looked through each with a telescope at more that 100x magnification. (Note that this is size and not position, so you won't be able to see these objects together through a telescope.)
In about one month, Venus will be closer, and because of the growth of the crescent shape, it will be easier to hang on to.
Just to make sure, this is a joke.
By February 1, the crescent moon joins the bright planets in the evening sky. If you can grab the moon and hang on, it will take you to Jupiter (also a joke).
Jupiter offers a few worthwhile transits, depending on whether you a day job:
Now, a look at the deep sky
Orion, redrawn as a climber.
Orion the Climber seems plausible, as it would explain this photo:
Of course, another explanation of this photo is what you get when you put a $1000 camera on a 5-dollar tripod.
As of Dec. 20, 2016, Mick Mulvaney is President-Elect Trump's choice for Director of the White House Office of Management and Budget. The Management side of the OMB is concisely stated on its website:
OMB oversees agency management of programs and resources to achieve legislative goals and Administration policy. (https://www.whitehouse.gov/omb/management)
Their website has a much longer, but thorough description of the Budget by policy objectives. These objectives range from creating a climate-smart economy, protecting and increasing water supply, crop insurance, preserving and protecting public lands and oceans, revitalizing manufacturing, biomedical research, civil space, agriculture, education, protecting workers, tax reform, health and safety, justice system, immigration, border security, terrorism, Russian aggression, humanitarian needs.... (https://www.whitehouse.gov/omb/budget)
At Skeptical Science we started some general posts based on questions from readers. I think it's a good service. Someone asks a reasonable and thoughtful question and gets a custom essay which may include illustrations. Or first in a series is here:
In the spirit of working with the President-elect, some of my international friends and I have linked the following individuals to Trump's Chinese global warming conspiracy:
Englishman William Herschel,
Frenchman Joseph Fourier,
Anglo-Irishman John Tyndall,
Swede Svante Arrhenius,
Americans Andrew Douglass and E.O. Hulbert,
Englishman Guy Callendar, and
Canadian-American Gilbert Plass.
Though there are many more individuals to be outed, we stopped at those doing their work before Trump was old enough to find conspirators on his own. Writing in the now foreign language of fact and reason, my friends argue that climate science is a proud accomplishment of Western civilization:
The Western Riverside Council of Governments is sponsoring a test of LED light fixtures considered for widespread use throughout western Riverside County. The new LEDs offer great improvements on energy consumption, aiming, and intensity control, but vary in how well they minimize light pollution, preserve a night-time ambiance, and disrupt circadian rhythms of humans and animals. Understanding the wavelengths of light, which humans perceive as color, is key to selecting lights that minimize negative effects.
WRCOG is sponsoring tours of the test lights. About a dozen manufacturers provided sample LED lights that were installed in various settings in the city of Hemet. Installations include commercial, roadway, and residential sites. The tour participants are invited to rate how they safe they feel and how well they see under each light as well as how much they like the aiming (e.g., you may like a light but not want it spilling into a your bedroom window, or maybe you would like it to spill a little into your front yard). Participants were discouraged from looking at each light directly and were not told of the lights' exact specifications on color temperature. I was a flawed participant because I was to eager to assess the glare and spectra of the lights for their impact on the night sky. My interests required looking directly at the lights and testing their output with my spectograph:
Photos taken with my spectrograph of a low-pressure sodium light (top)
and a new LED (bottom two)
A key specification in understanding the impact of a type of light on the night sky, and therefore, on Palomar Observatory and our ability to enjoy the night, is color temperature. Color temperature comes from the physics concept of black body radiation and is used to describe how a given unit of mass radiates energy when heated to different temperatures. If I took a chunk of matter and heated it to 2700 K, 4500 K, and 6000 K and measured the wavelengths of light emitted at each temperature, I'd have data similar to the following:
Diagram produced with my home-made Planck black body radiation curve generator
So, an object that is at 6000 degrees Kelvin (6000 K) will put out radiation all across the electromagnetic spectrum but the wavelengths at which it emits the most energy will be at the green part of the color spectrum. 6000 K is approximately the temperature of our sun, and its peak output is in the green wavelengths, but since our eyes are adapted to the full range of color produced by the sun, we perceive the sun's light as white. Any lamp matching the sun's output we will perceive as white and the color temperature specification would be 6000 K. If you see a light that has noticeably more blue color, like with some plasma TV screens, you might infer that it's color temperature is higher than 6000 K, perhaps 7000 K or 8500 K.
The blue spectrum of light affects human and animal health. More of it at night, when the body is trying to shut down for sleep, will disturb the natural production of hormones that regulate our health. That is why the American Medical Association has recently issued warnings about the wide spread adoption of lighting that peaks in the blue part of the spectrum. The blue end of the spectrum also scatters more readily in our atmosphere, and therefore, it creates more light pollution than lights on the red end of the spectrum. Consider a common observation, the sky is blue on a clear day and red at evening and sunrise. This is because the blue light gets scattered and the red light beams straight or bends only slightly. So, lights with a lot a lot of blue will be scattered back at us, creating for us the look of a gray sky with few stars. We see this effect on cloudy nights when the clouds reflect most of the light back to us and our bedroom windows glow with this light pollution.
Below is a light on WRCOG's test. I was impressed based on my visual observation. The color is similar to the color of low-pressure sodium, but offers more color rendition and is very well aimed, hitting the street only. But when I looked that the lights through my spectrograph, I was reminded that the real test will be scientific measurements of the lamp's spectra.
Below are two light spectra measured by Dan McKenna of Palomar Observatory. All I know about the specific lights are their designations within the test program (P104 and P46). I've added some annotations:
The photo composite below shows a comparison of three lights. The top and bottom are new LEDs that differ in the range of color produced. Both are rated at a maximum of 3000 K though I suspect that this rating doesn't accurately reflect the blue light in the bottom example.
This residential street corner provides a reasonably fair comparison of new LED to existing LPS:
This row of distant lights demonstrate that it's easy to aim the new LEDs. You see less flare from the new lights because most of the light is directed downwards.
The type of lights chosen now will have a great impact on our night sky. All offer excellent opportunities for energy savings, aiming, and dimming, but some will produce wavelengths that will take away some of the pleasant qualities of the night. I am, of course, biased, because I consider the night sky a key feature in my quality of life. I've learned to see well in low lighting by relying on my night vision. I've also learned that though you can perceive color better in white light, such lighting doesn't make me see detail better. But what is important to me may not be important to others, so it is important for others to participate in these tours to offers their opinions. I welcome diverse opinions here and will preserve any comments.
I use this blog as a companion to my website www.brightstarstemeculavalley.org, where I call attention to local light pollution and share my enthusiasm for science and astronomy. I'm also a contributor to www.SkepticalScience.com.