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National Capital Astronomers

About NCA

NCA logoServing science and society since 1937. The National Capital Astronomers (NCA) is a non-profit, membership supported, volunteer run, public service corporation dedicated to advancing space technology, astronomy, and related sciences through information, participation, and inspiration, via research, lectures and presentations, publications, expeditions, tours, public interpretation, and education. NCA is the astronomy affiliate of the Washington Academy of Sciences. We are also members of the Astronomical League, in fact NCA members helped form the Astronomical League a long time ago.

NCA has for many years published a monthly newsletter called Star Dust that is available for members. Besides announcement of coming NCA meetings and a calendar of monthly events Star Dust contains reviews of past meeting and articles on current astronomical events.

NCA is a very unusual astronomy organization. All are welcome to join. Everyone who looks up to the sky with wonder is an astronomer and welcomed by NCA. You do not have to own a telescope, but if you do own one that is fine, too. You do not have to be deeply knowledgeable in astronomy , but if you are knowledgeable in astronomy that is fine, too. You do not have to have a degree, but if you do that is fine, too. WE ARE THE MOST DIVERSE local ASTRONOMY CLUB anywhere. Come to our meetings and you will find this out. WE REALLY MEAN THIS!

Our Meetings

Monthly Meetings with Educational Presentations are Free and Open to the Public

NCA has regular monthly meetings September through June on the second Saturday of the month. Most meetings are held at the University of Maryland Astronomical Observatory in College Park, Maryland (directions/map).

Public transportation: Directions/maps to the UMD Observatory
Inclement weather: In case of severe weather (tornado/snow/impassable roads), a notice will be placed on the Observatory Website on the day of the meeting. (Be sure to refresh/reload the page to make sure you are seeing an updated page.)

Meeting Schedule for 2016-2017

Next Meeting Date: Saturday, 11 Feb 2017

7:30 pm at the University of Maryland Observatory on Metzerott Road.

Mars' intensifying effect on Phobos

Speaker: Dr. Terry Hurford, GSFC

Abstract: Phobos, the innermost satellite of Mars, is steadily spiraling closer to Mars, because the tides that Phobos raises on Mars lag behind Phobos’ orbital position, and thereby slow Phobos' motion.

As Phobos spirals closer to Mars, the tidal forces on it increase. Phobos will suffer tidal disruption before colliding with Mars in a few tens of millions of years.

Phobos displays an extensive system of grooves. They are mostly symmetric about its sub-Mars point, which is evidence that the grooves are being produced by tidal forces. We have calculated the surface stress field of the de-orbiting satellite, and found from the grooves that the first signs of tidal disruption are already present on Phobos' surface. Most of Phobos’ prominent grooves have an excellent correlation with computed stress orientations.

The model requires a weak interior that has very low rigidity on the tidal evolution timescale, overlain by a ~10 to 100 m exterior shell whose elastic properties are similar to lunar regolith or to powdery asteroid materials.

The fractures on Phobos' surface can be reworked daily through diurnal tidal stress, and may prove to be a natural seismic source for probing Phobos’ interior.

Bio: Dr. Terry Hurford is a Planetary Scientist in the Planetary Systems Laboratory in NASA's Goddard Space Flight Center. Both his undergraduate work and his graduate work were at the University of Arizona. As an undergraduate he won two Undergraduate Research Awards. During the summer of his Junior year, he was a research assistant at NASA Ames Research Center, in Moffett Field, California. As a graduate student in the University of Arizona's famed Planetary Sciences Department, he won a teaching award, and also began his extensive research on using geological science and expertise in orbital dynamics to obtain information on planetary moons and on other small bodies in the Solar System. This unusual combination of tools enabled him to infer aspects of the past, present and future states of those bodies that we wouldn't have been able to learn about otherwise. In 2005 Dr. Hurford started a post-doc at Goddard, where he is now a full employee.

Weather-permitting, there will be observing through the telescopes after the meeting for members and guests.


Join Us for Dinner Before the Meeting

Telescope-Making and Mirror-Grinding

Telescope-making and mirror-making classes with Guy Brandenburg at the Chevy Chase Community Center, at the intersection of  McKinley Street and Connecticut Avenue, NW, a few blocks inside the DC  boundary, on the northeast corner of the intersection, in the basement  (wood shop), on Fridays, from 6:30 to 9:30 PM. For information visit Guy's Website  To contact Guy, use this phone #: 202-262-4274 or Email Guy.

Come See the Stars at Exploring the Sky 2017!

Please check back in early 2017 for the 2017 schedule.

Exploring the Sky is a presentation of the National Park Service and National Capital Astronomers.

For NCA information by E-mail or phone

NCA Documents

HOME | Telescope Making Workshops | Exploring the Sky | Contact Info | Star Dust Archive | Links

Updated by E. Warner on 7 Feb 2017.