The Night Sky
LATE BREAKING NEWS: Three comets and a meteor shower may be naked eye visible before the end of the month! Early predictions expect October 21to be best viewing. C/2025 A6 Lemmon is closet to Earth Oct 21, C/2025 R2 Swan could be visible for the Northern Hemisphere (evening after sunset) and the interstellar comet 3i Atlas will be closest to the sun October 29th and may brighten. Peak night for the Orionid Meteor shower is October 21 and it is a New Moon.
Most of the planets are visible in the evening sky this month. The exceptions are Venus (low in ENE during morning twilight all month) and Mars (not visible at all). Mercury will be very low in the SW during evening twilight. Jupiter will rise in the ENE before midnight. It is presently in the constellation Gemini and close to the bright stars Castor and Pollux. Saturn will be high in the NE at dusk, will cross the zenith line before midnight and set in the W before 6 am. If you have binoculars or access to a telescope, Saturn’s rings are nearly edge on, so well worth a view. You might even be able to see one of the moons.
The ‘Mate Calling’ Full Moon will be on October 6. Through that week you may be able to see the bright star ‘Sirius’ in the morning daylight. This is the brightest star in Canis Major (Big Dog) constellation. The large and small dogs follow the hunter, Orion. Sirius is not far from Orion’s belt. To see a star or planet during the day, it is helpful to try to focus on some very distant object, like the edge of a cloud or aircraft.
October 9 sees the Moon in the Pleiades in the evening sky. This open cluster is to the west of Orion and makes up the shoulder of Taurus, the Bull. The red star, Aldebaran, is the eye of the Bull. The peak for the S Taurid Meteor shower is Oct 10th in the pre-dawn hours. These come from Comet Encke and last for a couple of months. They can have some very bright fireballs.
The 12th has Jupiter just S of the Moon. Last Quarter is on the 13th. Zodiacal light may be visible in the morning for the next two weeks and on the 16th the Moon will occult Regulus (the bright star in Leo). On the 19th Venus will be N or the moon. First quarter moon on the 29th and Mercury will be as distant from the Sun as it gets.
Shakespeare referred to the Moon as ‘inconstant’ and, from Earth’s point of view, it is. Although it is ‘tidally locked’ with Earth, how we actually see it changes throughout the year. The same face of the Moon is visible from Earth all the time, so the Moon’s ‘day’ is as long as our ‘month’(29.5 days). The first photograph of the far side of the Moon was taken by the Soviet Union’s Luna 3 in 1959. The Moon is known for its Phases, meaning the shape of the reflected sunlight we see from Earth. Throughout this the Moon remains a solid sphere
Let’s start with New Moon. we can’t see any of the lit parts from Earth. They are on the far side of the Moon. For an astronomer, it means sky will be dark all night long. A solar eclipse can only take place at New Moon.
What type of solar eclipse we see is dependent on how far or near the Moon is to Earth at New Moon. It varies a lot and the Moon changes how far South or North it can go.
Conversely, the lunar eclipse can only take place at Full Moon. The light of the sun is covering the entire face of the Moon that faces us. This can outshine the stars. The Moon also rises in the East as the Sun sets in the West.
The other phases are called Crescent, Quarter and Gibbous. These can be ‘waxing’ or waning. If the Moon is lit on the right hand side, it is waxing, left side is waning. DOC can be a memory aid. The crescent is thin and curved - between New and Quarter. The Quarter is where it looks like half the Moon is lit. But you are only seeing half the Moon, so you are seeing a Quarter. Gibbous meant a swelling, like a pregnancy.
The inner planets (Mercury and Venus) show us Phases as well. You can see this change with binoculars. Venus appears brightest to us when it is in its Crescent Phase.
To observe lunar details, try to find the Terminator (the line between light and shadow). This will look three dimensional.
Clear Skies.
