Obama to Shine Light on Unsung Hero of Astronomy
In his final DNews segment, President Obama will highlight Henrietta Swan Leavitt, whose insights helped devise a cosmic yardstick for measuring the universe.
Dig deep in the annals of astronomy and you'd be hard-pressed to find the name of Henrietta Swan Leavitt, a 19th-century astronomer whose ground-breaking insights about a special kind of star led to a cosmic yardstick for measuring the universe.
In 1923, Edwin Hubble used Leavitt's research to discover that a faint, fuzzy patch of light known as Andromeda was not part of the Milky Way, as scientists believed at the time, but instead was a separate galaxy. The universe suddenly became a much bigger place.
Hubble had found a type of star know as a Cepheid variable, which brightens and fades in a predictable pattern, much like a lighthouse beacon.
But it was Leavitt, toiling away at the Harvard College Observatory more than a decade before Hubble, who realized that a Cepheid's cycle was related to its intrinsic brightness. That insight gave scientists a reliable tool to measure cosmic distances since a Cepheid, like a 100-watt light bulb, would appear to be dimmer the farther away it is.
Leavitt made her discovery from photographs of the Small Magellanic Clouds, though her work was published under the name of her boss, Edward Pickering, a paper presented at a 2004 American Astronomical Society meeting shows.
"Her assignment at the time was to catalogue stars, not to investigate them. She made this famous and extremely valuable discovery on her own initiative," wrote Pangratios Papacosta, a physics professor at Columbia College in Chicago.
"Hubble's underwhelming acknowledgment of Henrietta Leavitt is an example of the ongoing denial and lack of the professional and public recognition that Henrietta Leavitt suffers from, despite her landmark discovery," Papacosta added "The vision of the cosmos was dramatically enhanced thanks largely to her discovery, yet no space telescope bears the name Leavitt and no USA postage stamp has been issued to honor her," he wrote.
More than a century after her ground-breaking work, Leavitt will be acknowledged by the highest office in the United States. President Obama will conclude his week-long stint as guest presenter on Science Presents DNews at 9pm ET/PT by talking about Leavitt's contributions.
Henrietta Swan Leavitt working at her desk in the Harvard College Observatory.
The Millionth Object is... an Exoplanet On Monday, July 4, the Hubble Space Telescope celebrated its latest milestone:
one million scientific observations
. Unfortunately, we can't "see" this landmark observation as a typically picturesque Hubble photograph as it was a spectroscopic analysis of a distant exoplanet's atmosphere. Analyzing the spectrum of light from worlds orbiting other stars is one component of Hubble's capabilities, but it's most famous observations recognized by fans of the space telescope are the amazingly detailed photographs of nebulae, galaxies, stellar phenomena and cosmic explosions. After 21 years, and a million observations, Hubble has transformed our perspective of the Cosmos, so in celebration of this latest milestone, Discovery News will take you on a journey of some of Hubble's recent, most striking imagery.
Hubble's millionth observation is of the exoplanet HAT-P-7b (a.k.a. Kepler 2b), a gas giant larger than Jupiter orbiting a star 1,000 light-years from Earth. HAT-P-7b was originally discovered by ground-based observatories in 2008 and it has since been studied by NASA's Kepler space telescope. To complement these observations, Hubble has been used to analyze the exoplanet's spectrum so the chemicals present in its atmosphere can be identified. What is Hubble hoping to uncover?
Atmospheric Water "We are looking for the spectral signature of water vapor," said Drake Deming of the University of Maryland and NASA's Goddard Space Flight Center in Greenbelt, MD. "This is an extremely precise observation and it will take months of analysis before we have an answer." "Hubble demonstrated it is ideally suited for characterizing the atmospheres of exoplanets, and we are excited to see what this latest targeted world will reveal."
21 Years Ago On April 24, 1990, shuttle Discovery launched with the 12 ton space telescope in its cargo bay, inserting it in a 559 kilometer (347 mile) around Earth. Last April, Hubble celebrated its 21st birthday.
"For 21 years Hubble has been the premier space science observatory, astounding us with deeply beautiful imagery and enabling ground-breaking science across a wide spectrum of astronomical disciplines," said NASA Administrator Charles Bolden. "The fact that Hubble met this milestone while studying a faraway planet is a remarkable reminder of its strength and legacy." Bolden piloted the space shuttle during the 1991 Hubble mission (STS-31).
Servicing Missions Since its launch, Hubble has been visited five times by space shuttle crews. The first time, in 1993, was famous for the extensive work that had to be carried out on the telescope to correct its optics – particularly an out-of-shape mirror. After 10 days of spacewalks, the seven astronauts aboard shuttle Endeavour managed to give Hubble 20/20 vision. The following four service missions by Discovery (1997 and 1999), Columbia (2002) and Atlantis (2008) all served to upgrade the telescope, re-boost its orbit (to counter the effects of drag caused by Earth's tenuous atmosphere at that altitude) and fix failed equipment.
End of an Era? Now that the shuttle fleet is about to retire, Hubble no longer has an in-orbit support crew. It's by itself and some time within the next few years, the command will be sent to direct Hubble toward Earth to finish its dazzling career as a fireball as it reenters the Earth's atmosphere. Sadly, it appears Hubble's successor, the James Webb Space Telescope, will be canceled, so it's far from certain what shape the next "Hubble" will take. Special thanks to Ray Villard for assisting with the Hubble image selection!