Administration: Individual. The DAB-4 is a revision of one of the most popular individual achievement tests available. Its 8 subtests identify studentsâ strengths and weaknesses across important areas of school achievement. A supplemental manual shows how to probe student responses to obtain information about studentsâ thinking processes and problem-solving strategies.
In 1992, the first evidence of a planetary system other than our own was discovered, orbiting the pulsar PSR B1257+12. Three years later, 51 Pegasi b, the first extrasolar planet around a Sunlike star, was discovered.
Bottom line: Since Pluto was discovered in 1930, astronomers have been speculating about possible large planets beyond it. But no additional large planets have been found at the edge of our solar system. New calculations by astronomers in Spain and the UK suggest that not one, but two unknown planets might exist in our solar system, beyond Plutoâs orbit.