By Jane Houston Jones
Saturn shines brightly from now through June below the distinctive constellation Leo, while Mars is visible nearly overhead during the evening this month. Between the two planets are two of the larger asteroids - one visible in binoculars and the other a challenge even with a telescope.
Vesta was the 4th asteroid discovered (in 1807), so its official name is 4 Vesta. It's a little over 500 kilometers in diameter and is the brightest of the asteroids because its orbit takes it closer to Earth and because of its high albedo or surface reflectivity. You can spot this magnitude 7 asteroid with binoculars within the sickle of Leo, the backwards question-mark of stars that forms the head and mane of Leo now through June. After June, Leo dips toward the western horizon and is lost in the glow of sunset.
21 Lutetia is more challenging and requires a star chart and a medium-to large telescope, plus dark skies on your eastern horizon. Lutetia was the 21st asteroid discovered (in 1852) and its diameter is only 100 kilometers. It is much fainter than both Vesta and all the surrounding stars in its area. It shines at magnitude 12, just a little brighter than Pluto! But a bonus for trying to spot the faint asteroid is its proximity to an eye-catching group of galaxies which are easier to see.
Toward the last two weeks of March and the first two weeks of April, you'll find Lutetia slowly nearing and then passing the distant galaxy M105. Two other galaxies - M95 and 96 - are nearby. You can see several galaxies in the photo inset. 21 Lutetia (circled in red) is closest to the faint galaxy M105 from the 20th to the 31st of March. Galaxy M95 can be seen center top above M96. So even if Lutetia proves too challenging for your skies, your telescope or both, you'll have had a great spring sky tour that includes a constellation, a bright asteroid, two planets, the stars of Leo, and several galaxies beyond our own Milky Way.
I took a look at all four objects earlier this month using my own 12.5 inch telescope. The view of Leo in-between the two colorful planets was stunning even without a telescope! And the asteroid hunt added a challenge to a great night of stargazing.
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