When NASA’s New Horizons spacecraft left on its mission to Pluto in January 2006, the latter was still listed as the ninth planet of the solar system. As the spacecraft begins its approach to Pluto nine years later, its target has been downgraded to a dwarf-planet or plutoid in the Kuiper belt, a disk-like collection of objects orbiting the Sun at 30 – 50 Astronomical Units (AU = 93 million miles).

Seven months after New Horizon’s launch, the International Astronomical Union downgraded Pluto’s status as a planet based on its size, among other criteria. Even though Pluto is smaller than Earth’s Moon, it has one major moon of its own, Charon, and at least four minor ones. The story of how Lowell Observatory astronomer Clyde Tombaugh discovered Pluto in 1930 is a fascinating one.

When New Horizons makes a flyby of Pluto on July 14 of this year it will pass within 7,700 miles and send back thousands of images of Pluto in never before seen clarity. It will also image Charon at 18,000 miles with researchers hoping that the data will provide new insights into the Kuiper belt considered a leftover relic of the formation of the solar system.

Focus on the Planets

Mercury peers above the east-southeast horizon about 45 minutes before sunrise in the first week or so of the month.

Venus dominates the western horizon as darkness falls, starting fairly low but climbing a little higher each successive evening.

Mars starts the month to the immediate lower right of Venus but sinks on the horizon as Venus climbs so the gap between the two increases nightly. No detail can be made out on the dim reddish-orange planet.

Jupiter is prominent high in the eastern horizon as March opens. Jupiter and the nearly full Moon will make a stunning duo on March 2. Telescopes will reveal the bands and zones on the planet’s surface, as well as the cavorting of the four moons as they orbit about and pass across the face of the giant planet.

Saturn rises shortly after midnight and is high in the south about an hour before sunrise. The tilt of the ring system presents a clear view of the Cassini division separating the A-ring and B-ring systems. Its large moon Titan is also readily visible by telescope.

Uranus is very close to Venus throughout the month and, on March 4, Venus passes within less than a tenth of a degree above the dim blue-green planet, the closest planet-planet conjunction for 2015. Mars, Venus, and Uranus are grouped in a tight circle less than five degrees across.

Neptune is too low in the dawn sky to be visible in March.

March Events

1: Sunrise, 6:14 a.m.; sunset, 5:22 p.m.

2: Brilliant Jupiter shines just to the left of the nearly-full Moon as night falls.

5: Moon at apogee or farthest distance from Earth. Full Moon, 1:05 p.m. The full Moon of March is called the Worm Moon, Sap Moon, or Lenten Moon.

7: Venus shines brightly in the west after sunset with much fainter Mars to its lower right.

8: This is the second Sunday in March and time to set your clocks ahead one hour as the nation goes from Standard Time to Daylight Saving Time.

12: The Sun enters Pisces on the ecliptic. Saturn shines just to the lower right of the Moon about an hour before dawn.

13: Last quarter Moon, 1:48 p.m.

15: The Ides of March, a bad day for Julius Caesar.

17: Happy St. Patrick’s Day!

20: New Moon, 5:38 a.m. The spring or vernal equinox arrives at 6:45 p.m. This is the point at which the Sun crosses the equator into the northern hemisphere. The Sun enters the astrological sign of Aries at the equinox.

21: Mars perches on the tip of the upper limb of the crescent Moon in the west as darkness falls.

22: The crescent Moon and Venus are paired in the west an hour after sunset with Mars far to their lower right.

27: First quarter Moon, 3:43 a.m.

31: Sunrise, 6:19 a.m.; sunset, 7:01 p.m.

Send astronomical queries to Clair Wood at cgmewood@aol.com or care of the Bangor Daily News, Features Desk, P.O. Box 1329, Bangor, ME 04402.