United States Naval Observatory facts for kids
Quick facts for kids Naval Support Facility US Naval Observatory |
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| Part of Naval Support Activity Washington | |
| Northwest Washington, D.C. in the United States | |
An aerial view of the United States Naval Observatory in 2004
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 NSF US Naval Observatory
NSF US Naval Observatory
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| Coordinates | 38°55′17″N 77°4′1″W / 38.92139°N 77.06694°W |
| Type | Military observatory and official residence of the US Vice President |
| Site information | |
| Owner | Department of Defense |
| Operator | US Navy |
| Controlled by | Naval District Washington |
| Condition | Operational |
| Site history | |
| Built | 1830 (as Depot of Charts and Instruments) |
| In use | 1830–present |
| Garrison information | |
| Current commander |
Captain Mark Burns |
| Garrison | United States Naval Observatory |
The United States Naval Observatory (USNO) is a special place where scientists and military experts work. They create important information about where things are located, how to navigate, and exact time. This data is used by the United States Navy and the United States Department of Defense.
The USNO started in 1830 as the "Depot of Charts and Instruments." It is one of the oldest science groups in the United States. Today, it is still the country's main facility for gathering information about space and time.
You can find the observatory in Northwest Washington, D.C.. It's near a famous area called Embassy Row. It's one of the few old observatories still in a city. In 1893, it moved to its current spot to get away from bright city lights, which can make it hard to see stars.
The USNO has done many important scientific studies. These include measuring the speed of light and watching solar eclipses. They even helped discover the moons of Mars! They also provided data for the first radio time signals. The USNO helped create some of the earliest and most accurate telescopes. They also played a big part in developing universal time.
Besides its science work, the USNO campus is also home to something special. Since the 1970s, it has been the official residence of the Vice President of the United States. This house is called Number One Observatory Circle.
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President John Quincy Adams wanted to create a national observatory. In 1825, just before he left office, he signed a bill to make it happen. He wanted it to be called the National Observatory.
For about 10 years, people used both "National Observatory" and "Naval Observatory" as names. Then, the Secretary of the Navy officially chose "Naval Observatory."
President Adams loved astronomy and spent many nights watching stars. He worked hard to bring astronomy to a national level.
The observatory officially began on December 6, 1830. It was ordered by Secretary of the Navy John Branch. It started as the "Depot of Charts and Instruments." Its first job was to fix and check navigation tools. It had a small budget and was led by Lieutenant Louis M. Goldsborough.
The First Observatory Location
In 1842, the observatory became a national observatory by law. Congress gave $25,000 for it. Lieutenant J.M. Gilliss was put in charge. He traveled to Europe to buy telescopes, other science tools, and books.
The observatory's main job was to take care of the Navy's ship clocks, maps, and other navigation gear. It checked the accuracy of these clocks. This was done by timing how long it took for stars to cross a certain line in the sky. It opened in 1844 in an area called Foggy Bottom. This was near where the Lincoln Memorial is now.
In 1893, the observatory moved to its current spot in Northwest Washington, D.C. This new location is on a hill called "Observatory Hill." It overlooks Massachusetts Avenue.
In 2017, the buildings at the USNO were added to the National Register of Historic Places. This means they are important historical sites.
The Time Ball and Accurate Time
The first leader of the USNO was Navy Commander M.F. Maury. He had the world's first vulcanized time ball made for the observatory. This special ball was created by Charles Goodyear.
The time ball started working in 1845. It was the first time ball in the United States. It was the 12th one in the world. Maury used stars and planets to keep very accurate time.
The time ball would drop every day except Sunday. It dropped exactly at noon, which was the middle of the day based on the sun's position. This helped ships and people nearby know the exact time. By the end of the American Civil War, the observatory's clocks were connected. They used telegraph lines to ring fire alarm bells in Washington, D.C., three times a day.
The USNO even did a special time-ball drop again in the year 2000 for a celebration.
Nautical Almanac Office
In 1849, the Nautical Almanac Office (NAO) was created. It was first in Cambridge, Massachusetts. In 1866, it moved to Washington, D.C.. It then moved to the US Naval Observatory grounds in 1893.
On September 20, 1894, the NAO became a "branch" of the USNO. However, it still worked mostly on its own for several years.
The USNO has the largest astronomy library in the United States. It also has the biggest collection of astrophysics magazines in the world. The library includes many rare old books about physics and astronomy.
Measuring Earth's Distance to the Sun
One of the early science jobs for the Observatory was to help figure out the Astronomical Unit, or AU. This is the average distance between the Sun and the Earth. This work was part of a project funded by Congress.
Scientists from many countries had been measuring the transit of Venus since 1639. This helped them get a more accurate AU. Naval observers used cameras to take pictures during the transit of Venus. They took 350 photos in 1874 and 1,380 photos in 1882.
By combining results from different places around the world, they found a very accurate distance. Their calculation showed the Earth-Sun distance was about 92,797,000 miles (149,340,000 km). This was a big improvement over earlier guesses.
Powerful Telescopes
The telescope used to discover the Moons of Mars was a 26-inch (66 cm) refractor telescope. It was first in Foggy Bottom. In 1893, it moved to the current Northwest DC location.
In 1934, the biggest optical telescope at the USNO started working. This 40-inch telescope was the second and last one made by the famous optician, George Willis Ritchey. His telescope design, called the Ritchey–Chrétien telescope, is now used for almost all major telescopes. This includes the famous Keck telescopes and the Hubble Space Telescope.
Because of too much light in the Washington D.C. area, the USNO moved the 40-inch telescope to Flagstaff, Arizona. A new Navy group, called the USNO Flagstaff Station (NOFS), was set up there. These operations began in 1955. Ten years later, the Navy's largest telescope, the 61-inch "Kaj Strand Astrometric Reflector," was built in Flagstaff in 1964.
The USNO still has its dark-sky observatory, NOFS, near Flagstaff. This facility now manages the Navy Precision Optical Interferometer.
Keeping Time for the Nation
By the early 1870s, the USNO's daily noon-time signal was sent across the country. It used the Western Union Telegraph Company. Time was also "sold" to railroads. This helped them schedule trains using special clocks. In the early 1900s, the time service was broadcast by radio. People with wireless receivers could get the Arlington time signal.
In November 1913, the Paris Observatory and the US Naval Observatory worked together. They used the Eiffel Tower as a giant antenna. They exchanged radio signals to figure out the exact time difference between Paris and Arlington, Virginia.
The U.S. Naval Observatory in Washington is still a main expert in precise time, Earth's movement, and observing space. It works with many science groups around the world. It figures out the timing and space data needed for accurate navigation, astrometry, and basic astronomy. It shares this information online and in yearly books like The Astronomical Almanac and The Nautical Almanac.
A former USNO director, Gernot M. R. Winkler, started the "Master clock" service. The USNO still runs this service. It provides very accurate time to the GPS satellites. These satellites are managed by the United States Space Force. Another Master Clock time service also operates at Schriever Space Force Base in Colorado.
Departments and Special Locations
In 1990, two new departments were created: Orbital Mechanics and Astronomical Applications. The Nautical Almanac Office became a part of Astronomical Applications. The Orbital Mechanics Department was led by P. Kenneth Seidelmann until 1994. Then, it was closed, and its jobs were moved to a group within the Astronomical Applications Department.
In 2010, the USNO's astronomy department in Flagstaff, Arizona, became its own command. It is now called the Naval Observatory Flagstaff Station (NOFS). It is separate from the main USNO in Washington but still reports to it. NOFS is located in the dark skies of the alpine forests near Flagstaff. It performs its national mission of creating the Celestial Reference Frame (CRF).
The Vice President's Home
There is a house on the observatory grounds at Number One Observatory Circle. Since 1974, this house has been the official home of the Vice President of the United States. It has very strong security from the Secret Service. The house is separate from the main Naval Observatory buildings.
This house used to be where the observatory's superintendent lived. Later, it was the home of the Chief of Naval Operations. Finally, it became the home of the Vice President.
How the USNO Provides Time
The U.S. Naval Observatory has two "Master Clock" facilities. One is in Washington, D.C., and the other is at Schriever SFB near Colorado Springs, CO.
- The main facility in Washington, D.C., has 57 special cesium atomic clocks and 24 hydrogen masers.
- The other facility at Schriever Space Force Base has 12 cesium clocks and 3 masers.
The observatory also uses four rubidium atomic fountain clocks. These clocks are extremely stable. The observatory plans to build more of these for both its locations.
The clocks used for the USNO's time system are kept in 19 special rooms. The temperature in these rooms stays very steady, within 0.1°C. The humidity is also kept constant in most of the clock rooms. The "Master Clock" time is created by combining the readings from many of these clocks. The clocks that are working most reliably are used more in this calculation.
The U.S. Naval Observatory offers public time services. You can get the time from 26 NTP servers on the internet. You can also call these phone numbers for voice announcements:
- +1 202 762-1401 (Washington, DC)
- +1 202 762-1069 (Washington, DC)
- +1 719 567-6742 (Colorado Springs, CO)
The voice you hear announcing the time has been the same since 1978. It belongs to an actor named Fred Covington (1928–1993).
The voice announcements always start with the local time (either daylight or standard time). You will hear a background of 1-second ticks. Local time announcements are made every minute, and also at 15, 30, and 45 seconds past the minute. The Coordinated Universal Time (UTC) is announced 5 seconds after the local time. When you first connect, you'll hear the second ticks for a few moments before the next time announcement.
The USNO also has a modem time service. It provides time to the Global Positioning System (GPS).
Instrument Shop
The United States Naval Observatory Instrument shop has been creating and building precise tools since the early 1900s.
See also
In Spanish: Observatorio Naval de los Estados Unidos para niños
