Saturday: One hundred five years ago tonight, astronomers Heber Curtis and Harlow Shapley were debating the distances of some of our farthest neighbors: galaxies. Curtis argued that the universe consisted of many galaxies millions of light years away. Shapley thought that the spiral structures seen in telescopes were close by as a part of the Milky Way. They also had different views on the size of the Milky Way. Learn more about their debate, called the Great Debate, at https://youtu.be/0MJCqJPMpeY. Learn more about the Milky Way by watching the center of it rise over the southeastern horizon at about 1:00 a.m.
Sunday: This morning, Venus is at its greatest illuminated
extent of this orbital cycle. The lit part of Venus has an area of 309 square
arcseconds. This is larger than any other planet in the sky but much smaller
than the full moon, which is about three million square arcseconds. (One
arcsecond is one three thousand six hundredths of a degree.) Venus is half a
fist above the eastern horizon at 5:00 a.m. Saturn is halfway between Venus and
the horizon at this time.
Monday: The Eta Aquarid meteor shower peaks just before dawn
on May 5 and 6. Since this meteor shower has a fairly broad peak range, you
should start looking before dawn every morning this week. The moon is close to
the new moon phase near the peak, meaning that the dimmer meteors will be
visible then. Meteor showers are named after the constellation from which the
meteors appear to originate. The meteors appear to come from a point in the
constellation Aquarius near the star Eta. This point is about one fist above
the east horizon at 4:00 a.m. The Eta Aquarid meteors slam into the Earth at
about 40 miles per second. They often leave a long trail. The Eta Aquarid
meteors are small rocks that have broken off Halley’s Comet. For more
information about the Eta Aquarids, go to http://earthsky.org/?p=158833.
Tuesday: Jupiter is two and a half fists above the western
horizon at 9:00 p.m. Mars is five and a half fists above the southwestern
horizon at this time.
Wednesday: Celebrate the ending of Global Astronomy Month by
reading some poems and short stories submitted by astronomy fans at https://my.astronomerswithoutborders.org/programs/astroarts/astropoetry.
Thursday: Some open star clusters are easy to find and see,
such as The Pleiades and The Hyades clusters in the constellation Taurus the
bull. Some are difficult to see. M35, an open star cluster in the constellation
Gemini the Twins, is in the middle. It doesn’t jump out at you, but it is easy
to find if you have help. M35 is about three fists above the western horizon at
9:30 p.m., halfway between the moon and the bright planet Jupiter. It is a
family of a few thousand stars about 3,000 light years away. Open star clusters
are young for stars, this one being about 100 million years old. The cluster is
best seen using binoculars or a small telescope.
Friday: Orion stands low in the southwestern sky. At 9:00
p.m., the middle of Orion’s belt is about one fist above the west-southwest
horizon. And talk about belt tightening! Alnilam, the middle star in the belt,
is losing mass at a rate of about 100 thousand trillion tons a day. That’s a 1
followed by 17 zeros tons per day.
The positional information in this column about stars and
planets is typically accurate for the entire week. For up-to-date information
about the night sky, go to https://nightsky.jpl.nasa.gov/planner.cfm.
All times are Pacific Time unless noted.
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