Notes about your surroundings.

LOOKING AT MARS: On Wednesday, Mars will be at its closest point to Earth in 17 years. Mars’ orbit around the sun takes 687 days, and the faster-orbiting Earth overtakes and passes it approximately every 780 days. This event is called an opposition, because Mars and the sun are on opposite sides of Earth.

Because the orbits of the two planets are not perfect circles and are not centered exactly on the sun, the distance between Earth and Mars during an opposition varies, depending on where in the orbits the event occurs. Wednesday’s opposition occurs at the point where the orbits come closest together.

This makes for ideal viewing of Mars. The closer the planet is, naturally, the larger it appears in a telescope and the easier it is to make out surface features. A telescope with a main lens or mirror at least 4 inches in diameter should allow viewers to see one of Mars’ brilliant white polar ice caps, as well as darker markings on the otherwise pale red surface.

The Museum of Natural History and Science in Newport Beach is offering a field trip Oct. 1 to the Orange County Astronomers observatory in Anza, about two hours from Orange County in San Diego County. The site’s 22-inch telescope will offer an excellent view of Mars and other heavenly bodies. Cost is $3 and space is limited. Call (714) 640-7120.