Woking Planetarium

Read our September sky notes to find out what’s in the night sky this month!

Map

Constellations

These constellations are well placed in the evening this month, but many more can be seen. Check the star map for more.

Perseus appears at dusk in the south east, moving across the sky towards the zenith throughout the night and across the course of the month. Look for it beneath and to the left of the bright constellation Cassiopeia.

Cygnus begins the night close to the zenith, before moving slowly towards the western horizon through the night. As the month goes on, it gets closer to the horizon by sunrise.

Orion, a winter constellation, is just becoming visible in the morning sky, a couple of hours before dawn. It rises due east and climbs higher in the sky before being drowned out by the light of the Sun. As the month goes on, it rises earlier each night and moves across the southern sky.

Planets

Mercury is too close to the Sun to be visible this month. Its highest point of 4° occurs on the 19^th, the same night that it reaches aphelion, its furthest point from the Sun. However, light from the Sun will drown it out.

Venus appears in the eastern morning sky, beginning in the constellation of Gemini and moving through Cancer into Leo. Its highest point occurs on the 8^th, when it will be 36° above the horizon. After this, it can be seen at gradually lower altitudes through the month. Venus is in conjunction with the Moon on the morning of the 14^th.

Mars can be seen in the late evening and morning sky, in the constellation of Pisces. It rises earlier as the month goes on, rising shortly after sunset by the end of the month. Mars has 2 conjunctions with the dwarf planet Eris on the 1^st and the 19^th. You will need at least a 4-inch telescope to see this. It is also in conjunction with the Moon on the morning of the 6^th.

Jupiter is visible in the constellation of Sagittarius in the southern sky from sunset onwards, setting in the early hours of the morning. As the month continues, it sets earlier, and by the end of the month sets before midnight. Jupiter is in conjunction with the Moon on the 25^th.

Saturn stays close to Jupiter, appearing in the constellation of Sagittarius in the southern sky. It can be seen from sunset onwards, setting in the early hours of the morning. By the end of the month, it sets before midnight, having set earlier each night. Saturn is in conjunction with the Moon on the 25^th.

Uranus is too faint to be seen with the naked eye. It appears in the southern sky, between the constellations of Aries and Cetus, moving from east to west over the course of the night.

Neptune is too faint to be seen with the naked eye. It appears in the southern sky, lower than Uranus. Near the constellation of Aquarius, it moves from east to west over the course of the night. Neptune reaches opposition on the 11^th, with its highest point occurring around midnight.

Meteor Showers

The September ε-Perseids reach their peak on the 9^th. The radiant (origin point) in the constellation of Perseus is circumpolar, so meteors will be visible all night. Best views will be shortly before dawn, as the radiant reaches its highest point around 05:00. There will be 4-5 meteors per hour.

The Sextantids reach their peak around the 27^th. It will not be visible before 04:41, when the radiant (origin point) in the constellation of Sextans rises in the east. Meteors will be visible through to sunrise. Best displays are likely to be shortly before dawn. The normal rate of meteors is 5 per hour, but as the radiant will be low on the horizon you are more likely to see about 1 per hour.

Moon

Full Moon: 2^nd

Last Quarter: 10^th

New Moon: 17^th

First Quarter: 24^th

The Moon reaches perigee, its closest point to the Earth, on the 18^th and apogee, its furthest point on the 6^th. This effect is not visually apparent.

The Moon will be at perihelion, its closest point to the Sun, on the 19^th and aphelion, its furthest point, on the 29^th. This effect is not visually apparent.

Look for Earthshine from the 11^th to the 16^th, and from the 18^th to the 22^nd.

Points of Interest

Asteroid 19 Fortuna reaches opposition on the 11^th. It can be seen between 21:37 and 04:14 in the southern sky, moving across from east to west. Around midnight, it will reach its highest point in the sky. You will need at least a 4-inch telescope to see it.

The September Equinox takes place on the 22^nd. On this day, everywhere on the planet has almost exactly 12 hours of day and night, as the tilt of the Earth’s axis is perpendicular to the direction of the Sun. This marks the first day of autumn.

Asteroid 68 Leto can be seen in the constellation of Cetus between 22:03 and 04:05 on the 30^th, when it reaches opposition. Appearing in the southern sky, it will reach its highest point in the sky around midnight. You will need at least a 4-inch telescope to see it.

The Zodiacal Light is visible during the early mornings towards the east, from the 17^th onwards. In skies without light pollution or the Moon, you should see a faint cone of light pointing southwards.

Visit Spot the Station to find out when the ISS will be visible from your location.

Last updated: 15^th September.