Handy Astronomical Facts

Useful for outreach volunteers or anyone teaching astronomy. All figures are approximate and designed with the NYC public in mind, in terms of analogies and units. Please add as many things as you like.

Rutherfurd Observatory/Pupin Hall

  • Rutherfurd Observatory was named for Lewis Morris Rutherfurd, a wealthy lawyer who was an amateur astronomer and one of the first astrophotographers (a rather expensive hobby in the mid-nineteenth century). His observatory was initially in the Stuyvesant estate on the Lower East Side, but he became associated with Columbia University (then around Rockefeller Center) as he and natural philosophers at Columbia shared a common interest in astronomical spectroscopy.
  • From 1906, approximately two decades before Pupin was built, telescopes were kept in the Wilde Observatory's dome and "transit building" where the Interdisciplinary Science Building now stands (an area formerly known as "The Grove"; see picture here: http://www.wikicu.com/File:WildeObservatory.png ). Transit observations were considered one of the most important aspects of astronomy even into the twentieth century for both time-keeping and navigation (Naval Observatories would announce the precise moment the sun crossed the meridian so that ships in the harbor could set their clocks in order to allow for accurate determination of longitude on the high seas). The current observatory still has a "transit room" with a slit oriented precisely north-to-south to aid in such observations.
  • Pupin Physics Laboratory was completed in 1927.
  • A twelve inch (30 cm.) refractor telescope built by the Alvan Clark firm in 1916 for the Czarist government of Russia was to be installed in Crimea to observe an upcoming solar eclipse and verify Einstein's theory of relativity. With unrestricted U-boat warfare during World War I shipment was delayed until the war ended. The new Russian government headed by Lenin refused to pay for or accept the telescope, which sat in a crate in a warehouse until 1920, when Columbia bought it. Upon the completion of Pupin Hall, it was located to the big dome which was built especially to house that telescope. The telescope was sold in 1997 to South Carolina State Museum that specializes in the upkeep of the old Alvan Clark refractors. They plan to use it for actual observing again very soon: http://www.museum.state.sc.us/plan_visit/observatory.aspx
  • In the 1970s, the "Columbia CO Survey" built a 1.2 meter radio telescope that operated out of the Little Dome and was the first to map the sky in this important radio band. See a picture of this at http://www.cfa.harvard.edu/mmw/mini_NY_210.jpg
  • Rutherfurd Observatory has been in continuous operation since Pupin was constructed, but in 2009 a new "Northwest Corner Building" was erected next to it, six floors higher than the roof of Pupin and blocking a significant portion of its field of view, and putting out a considerable amount of light, interfering with observations in the remaining sky.
  • Below the Rutherfurd Observatory on the 14th floor was the site of Professor Wallace Eckert's Astronomical Laboratory, in which he constructed the first device to perform general scientific calculations automatically in 1933-34 by connecting IBM punch card tabulating machines together, arguably inventing punch card programming. Eckert's expertise in this computational device was the reason he was appointed as director of the United States Naval Observatory at the beginning of World War II. His Columbia Astronomy Department replacement was refugee from Europe, Martin Schwarzschild (son of Karl Schwarzschild and later chair of the Princeton Astrophysics Department), who himself enlisted in the US Army and was eventually promoted to be an officer in the Army Intelligence Corps. After the war, Eckert returned to Columbia to head the newly-named Watson Scientific Computing Laboratory that worked in close cooperation with IBM. In 1957, Eckert's laboratory finally left Pupin Hall to the new campus at the Thomas J. Watson Research Center in Yorktown, New York, still the headquarters for the IBM research division.
  • Pupin Hall is also where Enrico Fermi, Leo Szilard, and other physicists began work on developing a self-sustaining neutron chain reaction in 1939, in the basement. When Fermi's work moved to the University of Chicago after Pearl Harbor so it would be safer from attack from the sea, it was called the Manhattan Project because of where it had begun, and it kept its name when it moved later to Los Alamos, New Mexico. Here is an article from the NYT describing the Manhattan roots of the Manhattan project: http://www.nytimes.com/2007/10/30/science/30manh.html?pagewanted=1.

Solar System

Saturn1 2

* 30 year orbit, on average 900 million miles from the Sun
* 10 hour rotation
* about 10 times Earth's diameter
* you could pack about 500 Earths inside Saturn (hard to find the exact number--look up sphere packing and enter a world of pain)
* has at least 61 moons
* average density is below that of liquid water
* composed of 96% Hydrogen, 3% Helium
* upper atmosphere temperature is -290 deg F
* the rings span 175,000 miles, 3/4 the Earth-Moon distance
* the rings are made of water ice particles ranging size from microns to cars
* the rings were probably formed in the early Solar System from the remains of a destroyed moon
* the rings have a complex structure of gaps and subdivisions created by gravitational interaction with Saturn's moons and moonlets

Titan1 2

* slight less than half the diameter of Earth, and slightly bigger than Mercury
* 16 day orbit around Saturn
* a dense atmosphere composed of 98% Nitrogen, with an orange smog made of organic compounds, that may partially resemble that of early Earth
* air pressure at the surface is 1.5 times that on Earth -- like being at the bottom of a swimming pool
* surface temperature is -290 F
* has Methane versions of rain, snow, seas, rivers, and lakes
* like on Earth, geological activity is driven by radioactive heat from the core
* has "cryovolcanoes" -- volcanoes that spew ammonia and water instead of magma


There are six trillion miles in a light year. The ratio of an astronomical unit to a light year is coincidentally close to that of the ratio of an inch to a mile. Light travels at the speed of one foot per nanosecond.

If the Earth's orbit around the Sun were shrunk down to the size of a quarter, a light year would extend about 10 short city blocks. In other words, a light year in this scale is 0.5 miles. Now you can make comparisons between the distances to the bright stars in our sky:

star dist. (lyr)
Altair 17
Deneb 1400
Vega 25
Pollux 34
Castor 50
Capella 42
Aldebaran 65
Betelgeuse 600
Rigel 800
Sirius 9
Arcturus 37
Mizar 78
Polaris 430