Autumn begins: what to look for in the Canarian sky
Today, 23 September, at 01:05 Canary time, autumn begins. This is not a calendar convention: it is an exact astronomical instant, the moment the centre of the Sun crosses the celestial equator.
Spain's national geographic institute puts it at 02h 05m mainland time, which here, one hour behind, is 01:05 this morning. If you were awake, it has already happened.
The instant is not the interesting part. What follows it is. For anyone who looks up, autumn is the better half of the year in the Canaries, and it is worth knowing why.
What actually changes from today
Three things, and none of them is the cold.
Nights lengthen faster than at any other time of year. Around the equinoxes the rate at which the day shortens is at its maximum. Within a few weeks you will notice it getting dark much earlier, and that means more usable hours of dark sky without staying up half the night.
The summer calima usually eases. It is not a rule, and Saharan dust can arrive out of season, but autumn air over the islands tends to be clearer.
The sky reshuffles. The Summer Triangle tilts west after dusk, and in the east the winter sky starts to climb.
What you can see in October and November without equipment
None of this needs a telescope. Just a dark sky, half an hour of dark adaptation and knowing where to look.
The Milky Way, still visible after dusk in the first weeks, running north to south. From a dark spot on the islands you can make out the band with its dense patches and its dark lanes.
The Andromeda galaxy, high in the eastern sky through autumn. To the naked eye it is a small elongated smudge. It is the most distant object the human eye can see unaided.
The Pleiades, rising in the east earlier every week. A small tight cluster that plenty of people mistake for the Little Bear.
The zodiacal light, a very faint cone of brightness above the horizon before dawn. It needs exceptional skies and no Moon at all, and the islands are one of the few places in Europe where it shows well.
For meteor showers and planetary oppositions month by month, the sensible move is to check the current year's calendar from an observatory, because the dates shift and the Moon matters more than the peak itself: an excellent shower under a full Moon looks worse than a mediocre one under a new Moon.
Why you see things here that you do not see elsewhere
The Canarian advantage is not only latitude, although that helps: from here you see southern constellations that never rise over central Europe.
The decisive factor is something else. The island observatories sit above the sea of clouds in stable air, and the darkness of the sky is protected by law. There is specific legislation governing outdoor lighting, flight paths and emissions that could degrade the sky above the observatories.
That is a rarity worth understanding: on La Palma and Tenerife the darkness does not survive by accident or by remoteness, but because a rule holds it in place.
Where to go tonight
The rule that works best is simple: go up and away from the coast. Most of the light pollution on the islands sits in the coastal strip, and a few hundred metres of altitude change the sky completely.
Three things that prevent most disappointments:
Check the Moon phase before choosing the night. It matters more than the location does.
Allow half an hour of adaptation without looking at your phone. Night vision takes that long to open up fully, and one glance at a screen resets it.
Bring more layers than seems reasonable. Up in the highlands, an October night bears no relation to the afternoon you left behind on the coast.
The specific spots, island by island, are in our guide to stargazing in the Canaries. If the plan involves going up Teide, read the permit and cable car guide first, because night access has its own rules.
And if you are considering La Palma, where the sky is at its best, our island guide helps with the rest of the trip.
Sources
Instituto Geográfico Nacional, Agenda Astronómica 2026: autumn begins on 23 September at 02h 05m. The agenda itself states that its instants are given in mainland official time, hence the conversion to Canary time.
Cover photo: Roque de los Muchachos observatory, La Palma. Photograph: Gianni0088, CC BY 4.0, Wikimedia Commons.
