Sky at a Glance May 25 – June 1

Photo showing location of the asteroid Ceres near Jupiter.

Photo showing wider view location of the asteroid Ceres near Jupiter.

This Week’s Sky at a Glance, 2019 May 25 – June 1 ~by Curt Nason

Asteroids, like comets, are solar system objects that some amateur astronomers like to collect; that is, identify them at least once with binoculars or a telescope. They are not as interesting to see as comets are, being just points of light, but they are usually more challenging to identify. If you are lucky one might be near an easily identifiable star or group of stars, and if you are even luckier you might be able to detect its movement relative to a star over several minutes or an hour. The few near-Earth asteroids that I have located, which can be seen moving in real time with a telescope, are among my lifetime observing highlights.

The first asteroid was discovered on January 1, 1801, and Ceres was initially called a planet once its orbit was calculated. In the 18th century a mathematical progression known as the Titius-Bode Law was formulated which fit the distances of the six known planets from the Sun. Uranus was discovered in 1781 and its distance fit that formula, but there was an inexplicable gap between Mars and Jupiter. Ceres filled that gap nicely, but over that decade three more new “planets” were found within the gap. Later in the century many more were found when astrophotography became a tool for astronomers, and now thousands are discovered monthly by automated telescopes programmed to look for asteroids that could potentially collide with Earth.

Ceres is by far the largest asteroid and it is now categorized as a dwarf planet along with distant Pluto, Eris, Makemake and Haumea. Ceres is at opposition on Tuesday and it can be seen easily with binoculars over the next month about a fist-width to the upper right of Jupiter. However, you will likely have difficulty distinguishing it from the stars. The Heavens-Above website has an Asteroids section which includes two maps for each of the brighter asteroids; one with a wide-field view of the constellations in the area, and an expanded inset with a binocular-size view showing the asteroid among the nearby stars. Currently, Ceres is moving westward relative to the stars and within a few weeks it will pass above the claws of Scorpius.

This Week in the Solar System

Saturday’s sunrise in Moncton is at 5:36 am and sunset will occur at 8:55 pm, giving 15 hours, 19 minutes of daylight (5:44 am and 8:58 pm in Saint John). Next Saturday the Sun will rise at 5:31 am and set at 9:02 pm, giving 15 hours, 31 minutes of daylight (5:39 am and 9:04 pm in Saint John).

The Moon is at third quarter this Sunday, rising at 2:21 am and setting at 12:38 pm. Mercury has moved into the evening sky, setting 50 minutes after the Sun by midweek. Jupiter is now getting high enough for late evening observing, while Saturn rises after midnight and is best seen in early morning twilight. Mars sets around 11:15 pm, and Venus continues to herald the sunrise by 50 minutes.

The Saint John Astronomy Club meets in the Rockwood Park Interpretative Centre on June 1at 7 pm. All are welcome.

Questions? Contact Curt Nason.

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