This is the Dudley Observatory Skywatch Line for Wednesday, May 9th, and Thursday, May 10th, written by Louis Suarato.
The 33% illuminated, waning crescent Moon sets at 1:46 p.m.,Wednesday. The two brightest planets shine in the evening sky, as magnitude -2.52 Jupiter rises at 7:51 p.m.., and Venus highlights the west-southwestern sky, at magnitude -3.95, until setting at 10:32 p.m. in the constellation Taurus. At 9:13 p.m., both planets will be at the same altitude of 13 degrees on opposite ends of the sky. Jupiter’s brightness is not only a result of reaching opposition on May 8th, it is also at its closest approach to Earth during 2018. On May 10th, Jupiter will come within 409 million miles of Earth. Saturn rises in Sagittarius at 11:51 p.m., followed by Mars at 1:13 a.m. near Capricornus.
The first view of the Milky Way is available as the constellation Cygnus rises in the southeast around 11 p.m… By 4 a.m., The Milky Way is visible from Cassiopeia, above the northeastern horizon, to Sagittarius, above the southern horizon. The center of the Milky Way lies at the westernmost part of Sagittarius. The distance to the galactic center is estimated to be between 24 and 28.4 kilolight-years. A kilolight-year is equal to 63,240,000 astronomical units. An astronomical unit is the average distance of Earth to the Sun, or 93 million miles. A radio source emanating from the center of the galaxy, known as Sagittarius A, indicates the presence of a supermassive black hole. The center of the black hole is estimated to have a diameter about the same as Mercury’s orbit around the Sun. The massive amount of cosmic dust between our solar system on the Orion Arm of our spiral galaxy and Sagittarius A prohibits us from viewing the galactic center.
For a full view of a galaxy, look toward the Big Dipper asterism in the constellation Ursa Major for M51, The Whirlpool Galaxy. Technically, M51 is in the constellation Canes Venatici, but it is easier to locate by following the handle of the Big Dipper to the last star at the end, known as Alkaid. M51 is located 3 degrees southwest of Alakid. If you are looking at the Big Dipper around 9 p.m., when it is upside down, M51 will be slightly above, and to the left, of Alkaid. M51 is 23 million light-years away, and spans 50,000 light-years across. Discovered by Charles Messier on October 13, 1773, The Whirlpool Galaxy is gravitationally affecting a nearby smaller galaxy known as NGC 5195. NGC 5195 was discovered by Pierre Mechain on March 20, 1773.