u/HolgerIsenberg

On 5 October 2026, Perseverance Rover reached 2000 Mars days (sols) on the surface! On that day an unusual sequence of 5 Navcam photos were taken at 30s intervals at local noon. Such sequences are known from the past shortly before sunrise or after sunset to look for the Martian moons or orbiters from Earth. Checking with Stellarium, the reason was revealed: Venus should be visible at -3mag and maybe even Earth at -2mag! I could see a faint white dot at the Venus location which doesn't appear as pixel defect on other frames from the same camera! Images from https://areo.info/mars20/ecams/2000

Yesterday I visited the Archenhold Observatory in Berlin, built in 1896 with 250000 German gold marks in private donations to Friedrich Simon Archenhold’s crowdfunding project as a public telescope for the Berlin Trade Fair. That’s $2.5 million in today’s USD! It is still the longest refractor telescope, at 21 m with a 68 cm lens, and most likely the fastest to rotate. Its still-original electromechanics let it rotate around the observer, who stays in the center—much different from common constructions, where you have to move around with a ladder. Unfortunately, a microcrack was recently noticed, and currently it can’t be rotated. The surrounding building was added in 1909 and is famous for being the location of Albert Einstein’s first public lecture on the theory of general relativity on June 2, 1915.

More about its history: https://www.planetarium.berlin/en/archenhold-observatory/history and https://astw.de/astronomiegeschichte/anfaenge_riesenfernrohr.php

Yesterday I visited the Archenhold Observatory in Berlin, built in 1896 with 250000 German gold marks in private donations to Friedrich Simon Archenhold’s crowdfunding project as a public telescope for the Berlin Trade Fair. That’s $2.5 million in today’s USD! It is still the longest refractor telescope, at 21 m with a 68 cm lens, and most likely the fastest to rotate. Its still-original electromechanics let it rotate around the observer, who stays in the center—much different from common constructions, where you have to move around with a ladder. Unfortunately, a microcrack was recently noticed, and currently it can’t be rotated. The surrounding building was added in 1909 and is famous for being the location of Albert Einstein’s first public lecture on the theory of general relativity on June 2, 1915.

More about its history: https://www.planetarium.berlin/en/archenhold-observatory/history and https://astw.de/astronomiegeschichte/anfaenge_riesenfernrohr.php

Now after the 12 August 2026 total solar eclipse I have made my ISS trajectory simulation script public so everyone can run it in the free GMAT astrodynamics software to simulate it under gravity, solar radiation pressure and atmospheric drag, including periodic apogee orbit boosts: https://github.com/isenberg/iss_eclipse

The purpose is to predict if the 2 August 2027 eclipse can be observed by the ISS crew on the space station from within the totality shadow (umbra) over northern Africa. I'll soon improve the script to be able to more easily delay the last boost burn by few hours before the eclipse which can adjust the orbital phase to perfectly intersect with the shadow for about 30 seconds. During the 2024 eclipse this opportunity was missed by about 8 minutes. During the 2026 no intersection of totality shadow (umbra) and orbital planed happened, only with the penumbra as visible in the screenshot.

The ISS crew will most likely have the rare opportunity on August 12 to observe a partial solar eclipse! At least that's my result for an orbit calculation based on its current position and estimated drag and solar radiation pressure using the NASA GMAT tool.

Around 13:10 EDT the station will be inside the penumbra for 8 minutes above Canada and later at 14:56 maybe again for a few seconds.

A total solar eclipse in the strict sense, where the Moon and Sun appear under the same angular diameter, was only once publicly documented as being observed by humans in space: By Jim Lovell and Buzz Aldrin on Gemini XII (other 3 photos).

Image shows screenshot I took of my GMAT orbit simulation.

Everyone can find their favorite Martian Sky Color in those original Mars pictures from 1976 - 1982! Blue and white during the usual clear weather, over gray and yellow to red during dust storm activity later in the mission. Even water ice surface frost on Viking Lander 2 during the winter!

I recently processed the original Viking Lander 1 & 2 digital 3x6 bits / pixel images in the same way as every digital camera converts raw sensor data into a visual images. Technically that's creating a camera profile (see last image info graphic) and applying it to create a standard sRGB JPEG. All color images from both Viking Landers from their mission duration 1976 - 1982 can be viewed for free via this link: https://areo.info

Top 10 countries ranked by their years of continuously king-free existence up to the present:

San Marino: 1725 years

Iceland: 1096 years

Switzerland: 735 years

United States: 250 years

Haiti: 222 years

Liberia: 179 years

Dominican Republic: 182 years

El Salvador: 185 years

Costa Rica: 178 years

Guatemala: 187 years

A great info graphic about the 3 Viking Lander life detection experiments was the centerfold in the article "Sifting for Life in the Sands of Mars" by Rick Gore in National Geographic January 1977 edition, Vol.151 No.1. The trinity: Pyrolytic Release Experiment (PR, PI Dr. Norman Horowitz, Caltech), Labeled Release Experiment (LR, PI Dr. Gilbert Levin, Biospherics Inc.), Gas Exchange Experiment (GEX, PI Dr. Vance Oyama, NASA Ames Research Center). I got the original old edition on ebay recently.

As above so below, the Perseverance Rover tracks are visible. 1900 Mars days (sols) now on the surface yesterday, 24 June 2026!

The 2nd image was taken by Mars Reconnaissance Orbiter 10 days ago and shows the rover from 300 km above. That's only possible with a clear atmosphere, like the sky seen from ground also shows.

Navcam / Watson images: https://areo.info/mars20/ecams/1900/ and even better with the areoHDR app

2nd image: PIA26726 from https://jpl.nasa.gov/images/pia26726-nasas-hirise-captures-perseverance-marking-a-milestone-on-mars/

Almagestum Novum in 1651 by Riccioli shows the lunar swirl today known as Reiner Gamma labeled as Galilæus. Then in 1834 Mädler's Mappa Selenographica changed the swirl label to γ and moved the name Galiläi to a small crater northwest where it remained until present.

I propose to revert this 1834 undocumented change and return Galilei Galileo to the original location at the swirl. To avoid confusion, using a new name, Galilaei Impulsus and keep the Galilaei name at the small crater.

More details, maps and photos and link to petition: https://areo.info/galileo

If you agree with the renaming, please sign the petition (also anonymously possible): https://c.org/q7QJTnj2Xx