Spacecraft observations indicate that a vast, unseen halo of hot gas envelopes our home galaxy, the Milky Way, and could literally be brushing up against its nearest neighbors. (p. 21)

Astronomers have for the first time caught a dying star at the very beginning of a brief, shining period, when it's known as a planetary nebula. (p. 8)

Astronomers are examining some of the brightest objects in the universe to learn about the darkest stuff. (p. 5)

Galileo spacecraft images show for the first time that material has slid downward along a cliff on Jupiter's moon Io. (p. 395)

Thousands of people in North America who got up early on Nov. 18 were treated to a memorable sky show: White, yellow, blue, and green fireballs, some leaving behind smoke trails, streaked across the sky. (p. 395)

Planetary scientists have for the first time detected sugar compounds in meteorites, bolstering the view that space rocks seeded the early Earth with ingredients essential for the development of life. (p. 388)

Astronomers have unveiled the first X-ray image of Venus. (p. 357)

Astronomers have for the first time detected the atmosphere of a planet that lies well beyond the solar system. (p. 340)

Using sound waves to obtain the first clear picture of the structure beneath the surface of a sunspot, scientists say they now have an explanation for why these dark blemishes-sites of intense magnetic activity-can persist for days. (p. 310)

In the early morning hours of Nov. 18, sky watchers in North America may be treated to one of the most spectacular displays of shooting stars they're likely to see for a generation, if not longer. (p. 293)

The largest dust storm seen on Mars in more than 2 decades is now beginning to wane. (p. 299)