An Astronomer's Guide to Seeing the Planetary Cluster This April
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From blood moons to partial solar eclipses, there's been no shortage of exciting astronomical events in 2025. Over the course of a couple of weeks in mid-April, early risers will get a treat looking to the east before sunrise: three naked-eye planets will be clustered low to the horizon, at times separated by just 8 degrees (less than the apparent size of your fist held at arm's length).
Meet the author: Dr. Phil Plait is an astronomer, author, and science communicator with a PhD in astronomy at the University of Virginia. He has written four books on astronomy and consulted on space TV shows and movies, including the 2016 hit, Arrival. He was also the head science writer for the first season of Bill Nye Saves the World on Netflix.
The planets are Venus, Mercury, and Saturn, and all you need to see them are clear skies, an unobstructed view to the eastern horizon, and a willingness to get up before dawn. Binoculars might help you spot the trio, though they aren't strictly necessary. The grouping is visible anywhere on Earth, though the closer you are to the equator, the easier it will be to see.
Of the three planets Venus is by far the most obvious, the third brightest natural object in the sky after the sun and moon, shining 25 times brighter than the other two planets. It's also highest above the eastern horizon, making it a cinch to catch even when the sky begins to glow with the impending dawn. Venus is closer to the sun than Earth is, which means it moves more rapidly around the sun. It just 'lapped' us in late March, passing the sun in the sky and sliding ahead of us in its orbit to become a 'morning star.' As it continues to move away from the sun, it will appear higher every morning at the same time.
Due to its changing geometry relative to the sun and Earth, we see Venus going through phases much as the moon does. By eye it will look like a brilliant star, but with binoculars it will appear as a crescent, much like the new moon. Its proximity to Earth—about 50 to 70 million kilometers from mid to late April—means we catch more of its light, so it appears extremely bright. It's often mistaken for an airplane or UFO.
Mercury is closer to the sun even than Venus, but is far smaller in physical size and also less reflective—Mercury's surface is mostly dark volcanic rock, while Venus is enshrouded in clouds that are far better at reflecting sunlight—making Mercury much fainter than Venus by eye. On top of that, it's also lower to the horizon making it harder to spot. While visible to the naked eye before dawn, binoculars will help here; sweep around the sky below Venus to spot the elusive planet.
Saturn will appear as the third vertex of this planetary triangle, just 2 - 3° from Mercury (roughly the width of two fingers held at arm's length) on April 10 through April 15. Even though Saturn is physically far larger than Mercury, at over 20 times wider, its distance of 1.5 billion kilometers from Earth is so much farther away that the two planets appear to be nearly the same brightness in the sky. Again, binoculars may help you spot it below Venus. The hazy atmosphere of the gas giant world will likely make it appear yellowish to the eye.
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Over a few weeks the individual motions of the planets change their relative positions in our sky; Venus gets higher fairly rapidly from morning to morning, while Saturn moves in a more stately fashion. Mercury is at its highest pre-dawn on April 11, and moves closer to the sun after that. The three are closest together between April 10 and April 13. The thin crescent moon joins the trio on April 24 and 25 as well, adding a bit of icing to this celestial cake (though by then Mercury may be too low to easily observe). I suggest going out over several mornings to see how they've moved.
How well you can see all of this also depends on your location. Near the equator the sun rises nearly straight up, perpendicular to the horizon, and the planets will be directly above it as they rise, making them much easier to spot. If you're in mid-latitudes north or south, the planets rise at more of an angle making them lower in the sky and more difficult to view when dawn breaks. Either way, your best bet is to be on the lookout about an hour before sunrise, compromising between the sky getting brighter and the planets getting higher in the sky and easier to catch.
A triple meetup like this is somewhat rare, so grab your chance (and a cup of coffee) and spot them while you can.
Originally Appeared on Condé Nast Traveler
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