365DaysDate: April 28, 2009


Title: A Galaxy of Astronomical Birthdays

Podcaster: Patrick McQuillan

Organization: Incorporated Research Institutions for Seismology (IRIS):

Description: Happy Birthday! Today we have a star clustering of astronomically important birthdays. A total of five birthdays are celebrated today that have astronomical significance. Three are universally famous: Jan Oort, Bart Bok, and Eugene Shoemaker. The other two are not as famous, at least not yet. We will explore the astronomical contributions of all of our birthday celebrants. For without them we might not understand the origin of comets, star-forming regions, and meteor impact sites on the Earth as well as we do now. We definitely would not have the humor in this podcast or even the podcast itself without the other two.

Bio: Patrick McQuillan earned a B.S. degree in Physics from the College of William and Mary. His senior research project involved determining the period of variable stars, most notably Alpha Auriga. This was at a time when collecting data meant going to the roof of the physics building, locating the research star by hand, and tracking the star manually by following a guide star in the finder scope. No GPS-auto-guiding-from-a-climate-controlled-remote-location! In the twenty plus years since then, he has explained astronomy to the general public as a Planetarium Director, the Education Manager for Challenger Center for Space Science Education, a NASA Solar System Ambassador, and currently explains Earth Science as Education and Outreach Specialist for IRIS. You can view current earthquake activity using the Seismic Monitor located on the IRIS website.

Today’s Sponsor: This episode of “365 Days of Astronomy” is sponsored by Astrocamp Summer Mission of Idyllwild, California. Help introduce a child to the world of Astronomy. Learn more at


Patrick: Hello, I’m Patrick McQuillan, Education and Outreach Specialist with IRIS, the Incorporated Research Institutions for Seismology, a NASA Solar System Ambassador and a former Planetarium Director. Welcome to the April 28th edition of the 365 Days of Astronomy podcasts.

Ryan: Happy Birthday to you! Happy Birthday to you! Happy Birthday to Jan, Bart and Eugene! Happy Birthday to you!

Patrick: We are celebrating three famous astronomers birthdays today, but it is also somebody else’s birthday today.

Ryan: The fifth president James Monroe.

Patrick: Well that’s not who I was thinking about. I was thinking about somebody who is standing next to me. Who else’s birthday is it?

Ryan: It’s my birthday!

Patrick: And how old are you today?

Ryan: Eight!

Patrick: Eight? Wow! Guess how old these famous astronomers are. One famous astronomer whose birthday is today is Jan Oort. And today he would be?

Ryan: 109

Patrick: Another famous astronomer was Bart Bok. He would be?

Ryan: 103

Patrick: And Eugene Shoemaker is our final famous astronomer and he would be?

Ryan: 81

Patrick: Our first birthday celebrant is Jan Oort. Jan Hendrik Oort was born on April 28, 1900 in the northern part of the Netherlands. Numerous contributions to our knowledge of the workings of the universe were discovered by Jan Oort. In 1924, he discovered the galactic halo, the roughly spherical group of stars orbiting the Milky Way galaxy. In 1927, he calculated the distance of the Earth from the center of the Milky Way, which is located in the direction of the constellation Sagittarius. He showed that the Milky Way had a mass of 100 billion times that of the Sun. He discovered that the light from the Crab Nebula is polarized and produced by synchrotron emission, electromagnetic radiation generated by electrons traveling near the speed of light through magnetic fields. Jan Oort is best known for suggesting that comets come from a common region of the Solar System. What did Mr. Oort think was at the edge of the solar system?

Ryan: A big cloud.

Patrick: Of What?

Ryan: Of Ice.

Patrick: And what does that ice make?

Ryan: Comets.

Patrick: What are comets?

Ryan: Big balls of ice, dust and rocks.

Patrick: How big are they usually?

Ryan: About 10 miles across.

Patrick: What happens to them when they get close to the Sun?

Ryan: They start melting and make a tail.

Patrick: Do they always have tails?

Ryan: No.

Patrick: Only when they are close to…

Ryan: The Sun.

Patrick: This spherical cloud of comets is located at the edge of our solar system and is the repository for the long period comets, comets with orbital periods in the hundreds to tens of thousands of years. This comet cold storage area is now known as the Oort cloud. Jan Oort died November 5 1992.

Bart Jan Bok was born on April 28, 1906. Not only did he share his middle name with Jan Oort, he was also born in the Netherlands. Bart Bok was an incredibly popular personality in the field of astronomy, noted for his friendliness and humor. The Asteroid 1983 Bok was named for him while he was still living. In the ceremony announcing the award, he thanked the IAU for giving him “a little plot of land that I can retire to and live on.” In 1929 he married fellow astronomer Dr. Priscilla Fairfield Bok, and for the remainder of their lives the two collaborated closely on their astronomical work. From 1929 until 1957 he worked at Harvard University. He then worked as director of Mount Stromlo Observatory in Australia for nine years, before returning to the United States as director of Steward Observatory.
His major astronomical interest was the structure of our galaxy, most notably in regards to the actual shape. He is mostly remembered today for his discovery in 1947 of small, very dark circular clouds visible against a background of stars or luminous gas and since known as Bok globules.

Patrick: What’s happening inside that cloud?

Ryan: Gravity is making it shrink.

Patrick: And what’s going to happen when it shrinks?

Ryan: It’s going to form new stars. This hypothesis was difficult to prove since the dense dark clouds obscure all visible light emitted from within them. A study of near infrared observations in 1990 confirmed that stars are indeed being born inside Bok globules. Bok died of a heart attack at his home in Tucson, Arizona on August 5, 1983.

Eugene Merle Shoemaker was born in Los Angeles California on April 28, 1928. For his Ph.D. at Princeton (1960), Dr. Shoemaker studied Barringer Crater. Eugene Shoemaker studied this hole in the ground and he found out there was something special about it.

Ryan: It was made by a meteor.

Patrick: Where is this whole located?

Ryan: In Arizona.

Patrick: And how come its still there?

Ryan: Because its in a desert.

Patrick: So there has been no rain to fill it up or wash it away. Meteor crater was formed 50,000 years ago. So how did he know it was a meteor that formed it?

Ryan: Because he studied the rocks. And there was a rock that you can only get when stuff gets smashed together hard.

Patrick: He studied craters that remained after underground atomic bomb tests at the Nevada Test Site at Yucca Flats. He found a ring of ejected material that included shocked quartz (coesite), a form of quartz that has a microscopically unique structure caused by intense pressure.

Dr. Shoemaker helped pioneer the field of astrogeology by founding the Astrogeology Research Program of the U.S. Geological Survey in 1961 at Flagstaff, Arizona. He was prominently involved in the Lunar Ranger missions to the Moon, which showed that the Moon was covered with a wide size range of impact craters. He was also involved in the training of the American astronauts. He himself was a possible candidate for an Apollo moon flight and was set to be the first geologist to walk on the Moon but was disqualified due to being diagnosed with Addison’s disease, a disorder of the adrenal gland. Coming to Caltech in 1969, he started a systematic search for Earth orbit-crossing asteroids, which resulted in the discovery of several families of such asteroids, including the Apollo asteroids. Since then, Shoemaker has done more than any other person to advance the idea that sudden geologic changes can arise from asteroid strikes and that asteroid strikes are common over geologic time periods.

In 1993, he co-discovered Comet Shoemaker-Levy 9. This comet was unique in that it provided the first opportunity for scientists to observe the planetary impact of a comet. Eugene Shoemaker, his wife Carolyn and another astronomer, David Levy discovered a comet that became known as Shoemaker-Levy 9. What was special about that comet?

Ryan: It got too close to Jupiter.

Patrick: And what happened?

Ryan: Jupiter broke it apart, to pieces.

Patrick: And then the comet smashed into Jupiter, and what happened?

Ryan: It made big clouds.

Patrick: Did it destroy Jupiter?

Ryan: No.

Patrick: Did the clouds stay there forever?

Ryan: No.

Patrick: Which one is bigger?

Ryan: Jupiter.

Patrick: A little bit or a lot?

Ryan: A lot.

Patrick: So the comet was too small to really do any damage to Jupiter, but it made a nice show. Shoemaker-Levy 9 collided with Jupiter in 1994. The resulting impact caused large dark clouds on the face of Jupiter that lasted for several months. Most scientists at the time were dubious of whether there would even be any visible markings on the planet. Dr. Shoemaker spent much of his later years searching for and finding several previously unnoticed or undiscovered meteor craters around the world. It was during one such expedition that Dr. Shoemaker died in a car accident while on the Tanami Road northwest of Alice Springs, Australia in July 1997.

On July 31, 1999, some of his ashes were carried to the Moon by the Lunar Prospector space probe. To date, he is the only person to have been buried on the Moon. The brass foil wrapping of Dr. Shoemaker’s memorial capsule is inscribed with images of Comet Hale-Bopp, the Barringer Meteor Crater, and a quotation from Romeo and Juliet reading
“And, when he shall die
Take him and cut him out in little stars
And he will make the face of heaven so fine
That all the world will be in love with night
And pay no worship to the garish sun.”
Ok. We have one final birthday for today. And the final birthday is who?

Ryan: Grandma.

Patrick: And without grandmom, who is my mother, I wouldn’t be here. And if I wasn’t here…

Ryan: I wouldn’t be here.

Patrick: And if both of us weren’t here there would be nobody…

Ryan: … to record the podcast.

Patrick: So I guess we should be pretty happy we have all those people having birthdays today: Grandmom, Ryan, Jan Oort, Bart Bok, and Eugene Shoemaker. SO…

Ryan: Happy Birthday!

TMBG: You’re older than you’ve ever been. And now you’re even older. And now you’re even older. And now you’re even older. You’re older than you’ve ever been. And now you’re even older. And now you’re older still.

End of podcast:

365 Days of Astronomy
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