Dial-a-Moon | 2019

How will the Moon look on any date in 2019? What will it look like on your birthday? Find out at NASA Dial-a-Moon. Here is Dial-a-Moon for southern hemisphere readers.

8 Feb 2019

Enter any month and day to see a high definition image. The composite images of Dial-a-Moon are made from those of the Lunar Reconnaissance Orbiter (LRO) in low altitude orbit around the Moon since 2009.

You may leave the universal time (UT) at the default value. Your local to Universal time conversion can be done at this link. Or, type ‘universal time’ into Google. Go back to Dial-a-Moon to enter the UT.

A Year of Moon Motions

The collection of accurate images of the Moon for each hour have been made into the movies below each lasting about 5 minutes. Try watching full screen for the best effect. Versions of the movie are available for readers in the northern and the southern hemispheres.

I explain the Moon’s peculiar wobble and tipping motions at this blog post.

Northern hemisphere

Southern hemisphere

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Cast a Long Shadow

Previously, I shared a post about a conversation with my son about the rising sun viewed at different latitudes. During that conversation, we also discussed how the length of our shadow varied over the course of a year. In winter at noon in the northern hemisphere, when the sun is low in the sky, our shadows are cast long to the north. In summer, our shadows are shorter due to the higher angle of the sun in the sky.

Imagine a plane extending through the earth at the equator. Extend that equatorial plane out into space. Between late March and late September, the sun appears above that plane. It reaches its highest extent in late June at the summer solstice. The sun appears at the elevation of the plane on the equinoxes in late March and late September. It appears at its farthest extent below the equatorial plane in late December at the winter solstice. The farthest north and south of the equatorial plane reached by the sun is 23.5˚.

Normal Shadows

Melanie and I live about 42˚ north of the equator. In the summer months, the sunlight direction is above the equatorial plane several degrees. Our short shadows are cast to the north at noon. In the winter months, the sunlight direction is below the equatorial plane. Our shadows are cast longer to the north. The blue man in this figure is not to scale, but illustrates the concept of casting of shadows.

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Christmas Morning | ISS Lunar Transit

Passes of the International Space Station are very predictable. There are internet sites that will email you notification of a coming pass. This one by NASA is easy to use. I use a site called CalSky which also notifies me if the ISS is going to pass in front of the Sun or Moon for my location. These transits are brief lasting barely more than a second. I’ve written about seeing several transits of the Sun in these posts.

Transits of the Moon are more difficult to see. The CalSky site has notified me fewer times about lunar transits. When they do occur for my location, the weather is sometimes a problem. This Christmas morning a transit was to occur but the forecast called for very cloudy skies. I woke not expecting to see it. When I looked out the window, the Moon was shining brightly in a clear patch of sky. I got my camera ready and hoped it would stay clear. It did just barely long enough. Here are three frame-grabs from the video showing the ISS just before, during, and after the transit.

This is the video slowed down to 50% speed. It is best viewed on a large screen with quality set to HD. It is not likely visible on a phone or tablet screen. The transit begins at the 7 o’clock position and ends at the 2 o’clock position of the Moon’s face. It lasts only 2.5 sec on this video, only 1.24 sec in real time.

I’ve waited a long time to see this. It was great to have it occur on Christmas morning. What a nice present.

DAWN Spacecraft | End of Mission

NASA’s DAWN spacecraft ran out of fuel used to point its antenna toward Earth. Communications failed on 31 Oct and 1 Nov 2018. It was launched in 2007 to study minor-planets Vesta and Ceres, the two largest asteroid bodies in our solar system. It achieved the mission goals which I have highlighted in several previous posts. NASA issued this press release about the DAWN mission which I encourage you to read.

DAWN was the first spacecraft to fly to a body of the solar system, descend into orbit, conduct science, ascend from orbit, travel to a second body, descend into orbit, conduct science, and all under the propulsive power of an ion engine instead of a chemical rocket engine.

Chief Engineer and Mission Director Mark Rayman reflects on the mission in this video.

 

Leon Lederman | How I Knew Him

There was sad news in the physics community about the death of Nobel Laureate Leon Lederman on 3 Oct 2018. He was 96. He lived a distinguished career in physics research and education.

1988 | Director of Fermilab

My first contact with Leon came in 1983 as a participant in the first Summer Institute for Physics Teachers held at Fermilab near Batavia IL. Participants met daily for several weeks. Several days each week started with a talk by a physicist explaining the state of research about fundamental particles which make up the world we know. We had special tours of the research facilities. Through these insights we were charged to include modern physics topics into our classroom teaching.

Dr. Lederman was the lab director at that time. His interest in science education often brought him to our group of teachers. He showed up at the talks, took some tours with us, and talked informally with us. He always carried a smile and had a good joke to tell. His hope for the Theory of Everything was that it would fit on a T-shirt. Simplicity of concepts was important.

Leon meets with the Education Office team | 1985

I took over as coordinator of the physics part of the Summer Secondary Science Institutes until 1992. That’s me next to Leon. The Fermilab Education Office had a farewell dinner in my honor when we moved from the area. Seated at my table that evening were my wife, my closest teaching colleagues, and Leon. I was thrilled to share the evening with him.

One sad facet of the news of his death included the fact that in 2015 he sold his Nobel Prize for $765,000 to pay for medical expenses related to his care in a nursing home for dementia. His wife said:

“It’s terrible,” Leon’s wife Ellen Lederman told NBC News back in 2015 after they had to sell the Nobel Prize. “It’s really hard. I wish it could be different. But he’s happy. He likes where he lives with cats and dogs and horses. He doesn’t have any problems with anxiety, and that makes me glad that he’s so content.”

It is inexcusable that this wealthy country does not have a plan in place to guarantee care and comfort to its citizens. I believe it should be a right. Leon Lederman certainly did his share of contributions to our country. He deserved better.

Aerosols on 23 Aug 2018

Aerosols are very small particles of matter in the air suspended by winds and air currents. The haze they cause can reduce visibility and redden sunrises and sunsets. The particles are much smaller than grains of sand. Common types are carbon from fires, wind blown dust from deserts, and salt from winds at the ocean surface.

The map below is a snapshot from 23 August 2018 showing where these three types were observed globally by satellite sensors. Color coding makes them easy to identify. A much larger version of this map is available at this link. The download allows you to zoom in on any of the regions shown. A previous aerosol post is here.

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U.S. Climate | April and May 2018

Two contrasting headlines about recent climate in the U.S. this spring caught my attention. Both came from NOAA’s National Centers for Environmental Information. The headlines were from the assessments of climate in the U.S. for April and May of 2018.

The contiguous United States had its coldest April in more than 20 years.

The contiguous United States had its warmest May on record.

Year-to-Date

The part of the U.S. where you live might not have seemed unusual. However, we noticed these differences in the midwest. Before examining April and May specifically, we will look at the climate for the year-to-date in the next two graphics. Relative to the period from 1895-2018, the upper plains was below average in temperature for the first five months of the year. The west was above to much above normal with record setting temperatures in the southwest.

Not shown in the graphic, the Alaska year-to-date temperature was 20.7°F, or 4.9°F above average. It was the ninth warmest on record. Western and northern Alaska were much above normal. Record low amounts of sea ice in the Arctic likely contributed to the warming.

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