Astronomical events of May 2025
The first days of May feature important astronomical events for both beginners and more experienced observers. Astrophotographers can capture impressive events, such as the opposition of Vesta, and beginners can capture the conjunction of Mars with the Moon.
Observation of the asteroid Vesta
Vesta, the most massive object in the asteroid belt and the third largest, will be visible to telescopes, thanks to its visible magnitude of 5.75, when it reaches opposition on May 2. An object in the solar system is said to be at opposition when it is directly opposite the Sun from Earth's perspective. During this time, it reaches its closest point to Earth in its orbit and remains visible for most of the night.
Amateur observers can try to view the object with small telescopes. If you're in Spain or Portugal, look through your telescope toward the south, above the constellation of Libra. The best time to see it is around 2 a.m. on May 2, 3, 5, and 6. The asteroid will move away from us until it becomes practically invisible on May 11.
Planetary conjunctions of the month of May
On May 3, 2025, in addition to taking advantage of the night to observe the asteroid Vesta, you will also witness a conjunction of the Moon and Mars. Our natural satellite passes 1° from the red planet over the constellation of Cancer on the night of May 3 at approximately 10:42 PM. Look with your telescope or binoculars toward the west.
This type of astronomical event will occur twice more during May. On the 22nd, it's Saturn's turn, which, in the early morning hours at approximately 4:27 a.m., will pass just 2º above the Moon above the eastern horizon before dawn. Something very similar will happen on the 23rd, also during dawn, but this time it's Venus that joins our natural satellite to form a beautiful conjunction, also before dawn, in an eastern direction above the horizon.
Eta Aquariid meteor shower
May 2025 also brings a meteor shower: the Eta Aquariids can already be seen in the sky tonight, but their peak is expected on May 6, when up to 13 meteors per hour can be observed.
The Eta Aquariids occur when Earth passes through a trail of debris left by Comet 1P/Halley. As the particles enter our planet's atmosphere at high speed, friction with the air heats them up and causes them to combust, creating bright flashes of light in the sky, called meteors .
To observe the meteor shower, it is recommended to visit places far from large cities and look toward the horizon, heading east, from 3 a.m. until sunrise.
The Eta Aquariids are most favorable from the Southern Hemisphere, with meteor showers increasing to a total of 45 per hour.
Locate the constellation Aquarius and enjoy this magnificent astronomical event.
Comet 1P/Halley
Comet 1P/Halley, also known as Halley's Comet, is the most famous comet and one of the few short-period comets visible to the naked eye from Earth. It has an orbital period of approximately 76 years, meaning it passes close to the Sun and Earth with that frequency. It was the first comet recognized as periodic, thanks to the calculations of astronomer Edmond Halley in 1705, who correctly predicted its return. Halley's Comet was last visible in 1986 and is expected to return in 2061. Its orbit is elliptical and retrograde, meaning it moves in the opposite direction to the planets around the Sun.
The Eta Aquariids are an excellent opportunity to see the trails of this important and well-known comet in our sky.