Using the National Science Foundation's Robert C. Byrd Green Bank Telescope, radio astronomers have found that Smith's cloud has a mass of at least one million solar masses and measures 3,000 parsecs (9,800 ly) long by 1,000 pc (3,300 ly) wide in projection.[5] The cloud is between 11,100 pc (36,000 ly) and 13,700 pc (45,000 ly) from Earth[5] and has an angular diameter of 10 to 12 degrees, approximately as wide as the Orion constellation, or about 20 times the diameter of the full moon, although the cloud is not visible to the naked eye.[2]