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(in 1946, an eighteen-year-old San Diego High School student wrote an essay in which he asked for plain courtesy when driving)
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“year”
The time it takes the Sun to travel around the center of the galaxy: A cosmic year, the period of revolution of the Sun around the galaxy, takes roughly 22.5 million years.
This entry is located in the following unit:
Astronomy and related astronomical terms
(page 7)
The distance traveled by a beam of light in a vacuum in one year, approximately 9.46 trillion (million million) kilometers or 5.99 trillion miles: A light-year has an average speed of 186,291 miles or 299,792 kilometers, per second; which equals approximately 5.88 trillion miles or 9.4607 trillion kilometers, or 63,246 astronomical units.
The light-year is also divided into light-minutes and light-seconds; for example, the Moon is 1.3 light-seconds from the Earth and the Sun is 8.3 light-minutes away from the Earth.
Although a light-year is a measurement of distance and not time, it does imply time, such as the light from a star that is ten light-years from the Earth takes ten years to reach the Earth. So, an observer on Earth is seeing the star as it appeared ten years ago.
This entry is located in the following units:
Astronomy and related astronomical terms
(page 14)
Measurements and Mathematics Terms
(page 7)
McGraw-Hill Year Book of Science & Technology
McGraw-Hill, Inc.; New York; 1992.
This entry is located in the following unit:
Sources of Information; Science and Technology
(page 1)
The 106-year-old Virginia McLaurin, an African-American, was very excited to meet the Obamas in the White House and she was dancing with joy.
Ms. McLaurin was invited as part of a Black History Month celebration. “I thought I would never live to get into the White House and I tell you I am so happy to have a black president,” she said to the smiling Barack Obama and the first lady, Michelle Obama.