... 1b. Pole Star . ... Two bright constellations occupy opposite sides of the pole star--the Big Dipper and Cassiopeia . ... The Big Dipper consists of 7 bright stars, forming a dipper, a small pot with a long handle. ... It shows the 7 stars of the Big Dipper and Polaris, the north star. ... Ursa Minor , the "Small Bear" or "Little Dipper" is a constellation somewhat resembling the Big Dipper, and Polaris is the last star in its tail. ... Questions from Users: About the stars of the Big Dipper . ...
Hubble Finds Oxygen Atmosphere On Jupiter's Moon Europa . Astronomers using NASA's Hubble Space Telescope (HST) have identified the presence of an extremely tenuous atmosphere of molecular oxygen around Jupiter's second moon, Europa . ... Europa's oxygen atmosphere is so tenuous that its surface pressure is barely one hundred billionth that of the Earth," said Principal Investigator Doyle Hall, of Johns Hopkins. ... The oxygen gas slowly leaks into space and must be replenished continuously. ...
Jupiter's volcano-pocked moon Io has been found by NASA's Galileo spacecraft to have a giant iron core that takes up half its diameter, scientists report in today's issue of Science magazine. The spacecraft also has detected a large "hole" in Jupiter's magnetic field near Io, leading to speculation about whether Io possesses its own magnetic field. ... Galileo scientists also are trying to determine the cause of the hole they found in Jupiter's magnetic field when the spacecraft was closest to Io. ...