National Capital Astronomers

About NCA

Serving 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. For 2023-24, meetings will be held in-person at the University of Maryland Astronomical Observatory in College Park, Maryland (directions/map) AND online via Zoom (details below). Seating is limited, so we are encouraging folks to attend via Zoom.

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 2023-2024

The meetings for this year will be HYBRID (online via Zoom AND in-person), unless otherwise noted!

With permission of the speakers, most meetings will be recorded. Once available the audio and video will be linked.

Online Meeting Information

National Capital Astronomers will be holding its 2023-2024 meetings online via Zoom and in-person. This year, the Zoom meetings have been set up so that there is no registration required. This is the direct Zoom link, it is the same for everybody for every meeting this year (2022-23). If we have problems with Zoom bombing at a meeting, then the link will be canceled and a new one created that will require registration for subsequent meetings.
As usual, the Zoom room "doors" open at 7pm ET with the actual meeting starting on time at 7:30pm! While you do not need to sign in right at 7pm, please do not wait until 7:35pm!! And since we are not registering folks, it will be important that you have a recognizable name showing so that I can let you in from the virtual waiting room.

Finally, as last year, with the permission of the guestspeakers, we will be recording the meetings.

Join Zoom Meeting: NCA Monthly Zoom

Zoom Etiquette

These guidelines will be updated as needed.

Multi-messenger Tomography of the Earth

Bill McDonough (UMD, Tohoku University)

Next Meeting Date: Saturday, 09 Mar 2024 -- (The meeting is hybrid, but the speaker is joining us from Japan.)

7:30 pm

Abstract: Geoscientists and neutrino physicists are exploring new ways of combining their methodological approaches and data to yield a multi-messenger tomography of the Earth. For the last two decades neutrino physicists have been detecting low energy (MeV) electron anti-neutrinos being emitted from the Earth (geoneutrinos), produced via ß - (electron) radioactive decay of U and Th. The radiogenic power driving the Earth’s engine has recently been determined from the flux of geoneutrinos measured at detectors in Japan and Italy (soon to be announced in a report from Canada), and from data from China. More recently, particle physicists have been sensing the Earth’s electron density via measurements of neutrino oscillations (thanks to quantum mechanics, a single neutrino will oscillate between being an electron-type neutrino, a muon-type neutrino, and a tau-type-neutrino) using 2-8 GeV neutrinos (e.g., measured by the KM3NET detector), and the overall matter density state of the planet has been mapped via neutrino absorption studies using =10 TeV neutrinos (e.g., the IceCube detector). Neutrino oscillation studies can tighten our estimates of the chemical composition of Earth, specifically testing models for the hydrogen content of the core. Sources of these latter high energy neutrinos are high energy cosmic ray collisions with air in the atmosphere, and interstellar sources of cosmic rays that interact with matter during their transit through the Universe.

Bio: Understanding the composition, structure and evolution of the Earth and the other terrestrial planets are dominant themes of my research. The differentiation of the Earth has created 3 separate and distinct reservoirs (i.e., the core, the mantle-crust system, and the atmosphere-hydrosphere system). These reservoirs are in turn themselves internally differentiated and powered in part by radioactively produced energy. Chemical and isotopic studies of terrestrial and meteoritic samples provide insights into the timing and details of the various differentiation processes occurring in these planetary domains.

My expertise is in analytical instrumentation and neutrino geophysics. Using laser ablation systems and plasma mass spectrometers for the chemical and isotopic analyses of samples I work with geologists, biologist, chemists, physicists and members of the US intelligence community. I am developing and improving upon methods of modeling and detecting the Earth’s geoneutrino (electron antineutrino) flux and anti-neutrino detection for nuclear monitoring. With my students we provide chemical and isotopic data that constrain geological processes and data for forensics, nuclear chemistry and archaeology.

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


Telescope-Making and Mirror-Grinding

Jan 2024

The telescope making, maintenance, and modification workshop with Guy Brandenburg is held in the basement (wood shop) of the Chevy Chase Community Center which is located at the intersection of McKinley Street and Connecticut Avenue, NW, a few blocks inside the DC boundary, on the northeast corner of the intersection. The workshop is open on Tuesdays & Fridays, from 6:00 to 9:00 PM. For information visit Guy's Website. To contact Guy, call 202-635-1860 or Email Guy.

Come See the Stars at Exploring the Sky 2024!

Exploring the Sky is a joint program between the National Capital Astronomers and the National Park Service Rock Creek Park Nature Center and has been run since 1948 at this location, the field at the corner of Glover and Military Roads in the District. There is an adjacent parking lot. It is free and all are welcome who have an interest in observing the heavens. It’s not an ideal dark sky location but we can still see solar system objects (even the occasional comet), open and globular clusters and maybe a fuzzy galaxy or two.

This year, as an added feature, you can come one hour early and see a planetarium program in the Nature Center and then come to the field to observe. Also, if the sky is cloudy or it’s raining there will still be a planetarium program at that one hour earlier time so Exploring the Sky will no longer be canceled!

Questions? Call NCA at 202-635-1860 and leave a message.

Download the flier

Date Time Things of interest
06 Apr 8:00pm Jupiter, Uranus, M45, Orion
06 May 9:00pm M44, Leo, Arcturus, M13
01 Jun 9:00pm Leo, Bootes, Hercules, M13
13 Jul 9:00pm Venus, Mercury, Moon, Hercules, M13, Summer Triangle
10 Aug 8:30pm Venus, Moon, Hercules, M13, Summer Triangle, M57
07 Sep 8:00pm Venus, Moon, Summer Triangle, Great Square of Pegasus
05 Oct 7:30pm Summer Triangle, Great Square of Pegasus, M31, Saturn
02 Nov 7:00pm Venus, Summer Triangle, Pegasus, M31, Saturn
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