July Skywatching | NASA

Venus Moon Size Comparison

On the morning of 17 June 2020, the Moon presented this nice crescent. The camera was at full zoom.

Eight days later, Venus presented in the same place at the same time with the same crescent shape. The camera was again at full zoom. The images are to scale.

Solargraph | Solstice to Solstice

My long time-exposure is finally finished. It lasted 6 months starting near the Winter Solstice in December 2019 until the Summer Solstice in June 2020. Done in three parts, sunrise solargraphs were merged into this one image. Previous solargraph posts are found here.

Sunrises between Winter and Summer Solstices

Starlink 8 | Morning Pass

On 13 June 2020, SpaceX launched 58 Starlink and 3 Planet SkySats into orbit atop Falcon 9. Many photos and video of the launch are available here and satellite details here.

Early in the morning of 17 June, that same set of satellites passed directly over my location. It was 4:45 am. Twilight was beginning to brighten the sky. I set my iPad on a stable surface and started a long 200 sec exposure with the NightCap app in ISS mode. Within a minute the train of satellites appeared in the southwest (lower left) heading northeast (upper right). The constellation Cygnus was directly in their path. You might recognize Cygnus as a set of short star trails in the center of the image.

Starlink 8 | NightCap ISS mode | 200 sec | 1/2s shutter speed

In the weeks and months ahead, the Starlink satellites will use their ion engines to move apart to higher altitudes of 341 miles (550 km) and become part of the constellation of about 12,000 when all are launched and deployed. More are planned. Since May 2019, about 538 have been launched in sets of 60 at a time. Another 1000 are expected in multiple launches this year. Details of the plan to deliver internet service can be found in a Wikipedia article here.

Gravity Lenses | Einstein Cross | Rings | Arcs

Albert Einstein published his General Theory of Relativity in 1916. One aspect of the theory predicted that light passing near a massive object would be deflected slightly in direction. Light originating from a distant bright source such as a quasar could travel by a massive object such as a galactic center and change direction. The observer would see the image of the distant source in slightly different places.

Not to scale.

Of course, such a prediction deserved to be tested. In 1919, astronomer Arthur Stanley Eddington headed a team to observe a star closely aligned with the Sun that would be visible only during a total eclipse. The star’s known position should be shifted according to the theory. Their observations confirmed that Einstein was correct.