From the Director





by Rex Parker, Phd

What’s Happening in AAAP
This month’s lecture on Feb 11 at Peyton Hall will deepen our look at our own favorite star, the sun, from the incredibly close perspective of NASA’s Parker Solar probe. Recent updates from Parker’s NASA blog on Jan. 29 indicated that in its latest (fourth) solar orbit the probe came closer than 12 million miles from the Sun’s surface and reached a speed of 244,000 miles per hour. These are unprecedented achievements in the history of science. See Ira’s section below for more on the speaker and specifics about the talk.

Meanwhile here in our local corner of the planet we patiently await clear nights, especially on weekends, for the opportunity to gather at AAAP’s Observatory in Washington Crossing Park for member training/refresher sessions with the astronomy equipment and software. Due to the challenges of weather this time of year, announcements for these sessions are likely to come on short notice – so please keep your eyes on the e-mail when signs of a clearing sky appear. I hope to see you out there over the next couple of months.

We are also aiming for a special observing outreach session on Feb 29 at the Friends of Hopewell Valley Open Space headquarters at the mansion (on the patio) at the Ted Stiles Preserve on Baldate Mountain in Hopewell Township ( To participate with your telescope go to the Calendar on our website and send a note to

Princeton Legacy of the Space Telescopes
Here among the ivy-trailed towers and steeply slanting lecture halls across our benefactor university, many tales intertwine to speak of deeds worthy of our remembering. So many bright stars of astronomy have called Princeton University home through the decades.

The Spitzer Space Telescope has gone out with a flare of news and publicity recently as it concluded its scientific career on January 30, 2020. It made numerous discoveries from exoplanetary to galactic research in its nearly 18 year life, longer than ever expected. The Spitzer telescope’s earth-trailing solar orbit was the first among spacecraft. Rather than circling Earth as Hubble does, Spitzer orbits the Sun but moves more slowly and drifts farther away from earth each year. Spitzer was one of NASA’s four orbiting Great Observatories which spanned the wavelengths and together enabled concomitant observations of deep space across the spectrum: Spitzer (infrared), Hubble (visible), Compton (gamma ray), and Chandra (X-ray). Each wears the name of a luminary of astronomy and astrophysics. Did you realize that the Spizter was named for a Princeton University icon?

An earlier chapter in this story begins with Spitzer’s mentor at Princeton, professor Henry Norris Russell (also director of the Princeton University Observatory). In the early 1910’s, Russell’s trail-blazing work and intellectual abilities led him to deep insights about the fundamental relationships between temperature, size, distance, and luminosity of stars. He developed a profoundly elegant formulation which today is known by students and amateurs alike as the Hertzsprung-Russell (H-R) diagram. Independently established by Russell and the Danish astronomer Ejnar Hertzsprung, the H-R diagram can be used to directly infer a wide range of stellar astrophysical properties. As Russell continued his work at Princeton he mentored several young PhD students, one of the brightest being Lyman Spitzer, who received his doctorate in 1938 and went on to astrophysics fame. Spitzer made big contributions in stellar dynamics and plasma physics over many decades at Princeton. He became one of the main drivers of thermonuclear fusion research in the 1950s, culminating in Project Matterhorn which in 1961 became the Princeton Plasma Physics Laboratory. Today Spitzer’s stellarator fusion design prototype can still be seen in the main lobby at PPPL. He is acknowledged as the first to seriously conceive and promote development of space-based telescopes, and was a force in the creation of the Hubble Space telescope.

It is this legacy which NASA honored by naming the Spitzer Space Telescope back in the early 2000’s. Over the next millennium, this reminder of the incomparable history of great astronomers at Princeton will continue its now lonely journey watching over the planets and stars, a sentinel for the remarkable scientific achievements of its namesake and lineage.

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