Lighting Advice for Borrego Springs
You can help protect Borrego's night sky from the increasing problem of light pollution.
Making small improvements to lighting can lead to huge improvements in the quality of our dark night sky.
courtesy Yorkshire Dales UK National Park Authority
Sky Calendar: April — May 2025
By Dr. Randolph Baron
| April 12 Sat | Full “Pink” Moon rise at 7:17 p.m. |
| April 21 Mon | Lyrid meteor shower See below |
| April 24 Thurs | Conjunction of Moon and Venus rising at the eastern horizon at 4:14 a.m. |
| April 30 Wed | Conjunction of Moon and Jupiter visible around 7:44 p.m. above western horizon |
| Early May | Sunrise 5:57 a.m., Sunset 7:28 p.m. |
| May 3 Sat | Conjunction of Moon and Mars visible around 8:08 p.m. high above southwestern horizon |
| May 3 Sat | Eta Aquarid meteor shower See below |
| May 12 Mon | Full “Flower” Moon rising 8:04p.m. |
| May 22 Thurs | Conjunction of Moon and Saturn rising at eastern horizon around 2:48 a.m. |
| May 23 Fri | Conjunction of Moon and Venus rising at eastern horizon around 3:28 a.m. |
THE PLANETS IN APRIL AND MAY
Venus will be a morning planet and rises 70 minutes before sunrise in early April.
Mars and Jupiter are early evening planets but are setting closer and closer
to sunset. By late May Jupiter sets only an hour after sunset. Saturn is difficult to
see in both months as it rises just before the sun giving us only a small window to view it.
If you do view Saturn through a small telescope you will note that its rings appear almost
edge on. This is due to the fact that Saturn, like the Earth, is tilted on its axis of rotation.
In fact, Saturn’s tilt is not too dissimilar to the Earth’s. Our tilt is 23.5 degrees, and
Saturn has an axial tilt of around 26.7 degrees, giving the planet seasons. But a year on Saturn
is 29 Earth years so a season on Saturn is over 7 of our years! So when Saturn is near
an equinox we see its rings appearing much thinner. And when Saturn is near a solstice
we see its rings appearing much wider. Over the coming months and years the rings will
again be opening up until a maximum in 7 years.
The Lyrid meteor shower is one of the oldest recorded meteor showers with observations going back to around 687 B.C. The shower is visible over three nights centered around the predicted maximum. This year the predicted maximum is around 6 a.m. on the morning of April 22 so the best time to observe this shower would be late night of April 21 into the morning of April 22.
The Eta Aquarid Meteor shower occurs when the Earth moves through debris left by none other than Haley’s Comet. This shower is predicted to peak on the night of May 3-morning of May 4.
Sky Quality Meter Readings for Borrego Springs
A Sky Quality Meter (SQM) measures the luminance of the background night sky, in units of magnitude per square-arc-seconds. In essence, this indicates the magnitude that the integrated luminance over a square-arc-second in the same measure as used for stars. A good human eye, on a dark night, can see 6th magnitude or slightly darker. SQM readings over 20th magnitude indicate a dark sky with good visibility; and readings above 21st magnitude,which are common in the Borrego Springs area, represent truly excellent skies.
The readings presented here are from a location on St. Vincent Drive, about ¼ mile from the Borrego Springs High School; readings in more remote locations would be expected to be somewhat higher. The graph presents the reading from the previous night, with options to allow users to explore earlier data as well. The iconic marks on each reading indicate various impacting factors, such as moon brightness, estimated cloudiness, etc.
