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If April showers bring May flowers, we should be in for a lovely roadside view soon. Although stargazers lament both clouds and rain, they are necessary, and I am sure when we have flowers to enjoy and food to eat, we realize rain is absolutely necessary.
When the clouds leave and the skies are dark, then we can expect to see the dependable spring/early summer constellations crossing the darkening evening sky. Because Earth rotates on its axis from west to east, in the west, we are still be able to enjoy the brilliant planet Venus for a while after sunset. The rate of rotation for us at our latitude is 898.54154 mph. At other latitudes the rate of rotation is different. As our part of earth moves, the stars and planets, the sun and moon, all will rotate into and out of sight.
Those constellations in the northern sky seem to rotate counter-clockwise about a single point, the star we call Polaris. This star is the last one in the tail of Ursa Minor, which is also the last star in the handle of the asterism Little Dipper. Observing the dippers early in the evening the Big Dipper will be high above, spilling its contents into the smaller dipper which will be very low towards the horizon. The leading stars of the Big Dipper are also known as the “pointer stars” because they direct the line of sight to Polaris at the end of the Little Dipper’s handle. Go back inside and chat with family a while, then go outside and see how much those circumpolar asterisms have rotated. You might be surprised.
Parameters of constellations are geometrically described via lines of latitude and longitude; asterisms are secondary patterns of stars within some of the constellations.
This is why the summer constellation Sagittarius is the larger group, half-man, half-horse, and an archer, while the Teapot asterism is the smaller geometric pattern of stars within the bow of the archer. It is easier to distinguish the Teapot than the centaur Sagittarius. The series of triangles formed by the teapot’s stars create the spout, which is giving off steam from stars in the Milky Way, another triangle marks the lid, another the handle, and stars of those create the trapezoid of the pot itself.
The same is true for the Ursid constellations. They look nothing like a bear, yet connecting some of the stars will make a pattern that resembles the old-fashioned ladles used to dip soup or water from large containers. Depending on the culture of the folks telling the tales connected to the star patterns, a person was seeing a plough, a drinking gourd, a hay wagon, or even a battle axe. What would you see?
Although these stars appear to be on the same plane, they are definitely not. Five of the stars are a true cluster and are about 80 light years distant from here. One is about 70 ly, others range from 105 ly to 210 ly distant.
On May evenings, our planet is standing straight up and down in the Milky Way Galaxy, parallel to the axis of the galaxy. The Milky Way lies flat along the horizon in every direction. May is a good time to look for things outside our galaxy, but you will need a decent telescope and a dark site to locate them. You might consider joining the South Texas Astronomical Society’s May 5 between 8 and 11 p.m. at the Resaca de la Palma state park to celebrate the 5th anniversary of the Christina Torres Memorial Observatory. Share the views through the very nice telescope there and learn more about astronomy. The park charges a fee but not the observatory itself.
Until next time, do let some stars get in your eyes and KLU.
