Trapezoid in the Sky

Last night at about 10 the space station passed overhead. It was a chance to see it pass near Venus and Mars plus the stars Pollux and Castor of the Gemini twins. The iPad app Nightcap captured the scene including 3 airplanes. Their trails completed a trapezoid in the sky during the 147 sec exposure. That was an interesting surprise.

Taken with NightCap, ISS mode, 147 sec exposure, 1/2 sec shutter speed.

Evening Planets | April 2023

Mercury reached its greatest elongation from the Sun in the evenings of April 11-14. We were fortunate to have clear skies during some of those days. At about 8:45 on the 12th, I went out with camera and tripod to see if I could get an image. It was easy to locate a little north of west and about 17˚ above the horizon. Here it is with a few guy wires from a nearby radio tower cutting the corner of the frame.

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stratospheric balloon over iowa

More about high altitude balloons.

Our View From Iowa

I enjoy checking the air traffic over our area using a site called ADS-B Exchange. Their zoomable map shows all the flights anywhere in the world. We live under the flight paths of many planes crossing the country. That is why we are sometimes called a flyover state. Their map includes the smallest one-runway airstrips scattered around the country which support a lot of single engine planes. We also can watch the helicopter traffic over us carrying patients to the University of Iowa Hospital for care. By clicking on an aircraft symbol, it brings up windows with flight details about the aircraft, how high, direction, speed, etc.

Today, I noticed something unusual on the map. It was not a symbol showing an airplane or helicopter. It was a symbol shaped like a hot air balloon. I’ve seen that symbol only one time before on the map. The info window…

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Vernal Equinox 2023

The spring equinox took place on 20 March 2023 in the afternoon. To celebrate the event, I set up a week-long time exposure with a pinhole camera pointing south from a window of our house. I was able to capture the passage of the Sun across the scene during several cloudless days. The equinox day is visible here as the top dark trace. Go here to see how to make solargraphs.

The photo paper from the pinhole camera was put on the flatbed scanner. Software was used to increase the contrast with this result. Bright sunlight caused dark exposure. Lack of light is white. Part of our house is at the left. The straight edge of the window frame is at the upper right. Tree trunks and branches fill the center. Some neighbor’s houses on another street are across the bottom. The pinhole arrangement gives a distorted fisheye effect.

Software was used to invert this negative image into a positive one for a more familiar appearance.

Wolf-Rayet 124 | Two views

Wolf-Rayet stars are rare and extremely luminous. They were first discovered in 1867 at the Paris Observatory by Charles Wolf and Georges Rayet. They have masses exceeding 20x that of our Sun and have surface temperatures well over 25,000 Kelvin. Our Sun’s surface is about 6,000 K. Of the billions of stars in the Milky Way galaxy, only a few hundred are known to be Wolf-Rayet stars. Strong winds blow out from their atmosphere and eject material into shells of hot glowing gas surrounding the star. Radiated energy by Wolf-Rayets is many orders of magnitude greater than our Sun. It peaks in the ultraviolet part of the spectrum. Their lives are relatively short.

The James Webb Space Telescope observed Wolf-Rayet 124 in June 2022 using the infrared detector MIRI here seen on the left in purple hues. This recently released image reveals details of internal structure.


The Hubble Space Telescope imaged WR124 back in 1997. It used visible light filters to make the image. They were combined to create this false color version showing details of the gaseous nebula around WR124.


I learned how to overlay and compare the two images using this slider tool available in WordPress. Drag the divider left and right.

Left: JWST – Right: Hubble

I first saw this comparison tool in a post by fellow blogger TextileRanger. She writes Little Wild Streak about nature and Deep in the Heart of Textiles about working with fabrics. Take a look at her posts.