As the Roman god who baptized him, Mercury runs very fast in the sky. Its orbit close to the Sun makes the year only 88 days long - and makes the planet particularly difficult to observe. But a good opportunity happens now, in the last days of January.

Mercury will reach its highest point above the horizon this Wednesday (27th), but it will already be very visible today. If you are in São Paulo, the planet will reach an altitude peak of 14 ° above the western horizon, close to the time of sunset, and set at approximately 20pm.


The smallest planet in the Solar system it will shine five times brighter than normal - so bright that you should be able to spot it with the naked eye. Of course it depends on the weather, but if you have clear skies and an open view, you should have no problem finding it.

Mercury does not have a thick atmosphere to protect it from space debris, so it is riddled with craters, such as the Caloris Basin, which is 1.525 kilometers in diameter. Image: Nasa / Johns Hopkins University Applied Physics Laboratory / Carnegie Institution of Washington

Mercury's orbit is closer to the Sun than to Earth, which means that the planet always appears close to the star and is lost in its brightness most of the time. Therefore, it is observable for only a few weeks at a time - when it reaches greater separation from the Sun.

How to orient yourself

To follow the movement of the stars, it is important to know in which direction to look and how to identify the main cardinal points. To do this, you can use an old trick, a compass or an astronomy app on your cell.

The old trick is based on a phrase you must have learned at school: “the sun rises in the east and sets in the west”. Stand and stretch your arms, with your right pointing towards the east, and your left towards the west. Then you will have east to the right, north to the front, west to the left and south behind you.


As for compasses, anyone using an iPhone doesn’t need an extra app: just use the “Compass”, Which is part of iOS. For Android we recommend “Just a compass”, From PixelProse SARL, which is beautiful, simple, free and, most importantly, ad-free.

SkySafari uses a compass and GPS to identify the stars the phone is pointing at. Image: Simulation Curriculum

Another option is to use an astronomy app, which uses the cell phone's compass and your location obtained via GPS to identify what you are aiming for or indicate where to look. A good option is Sky Safari, from Simulation Curriculum Corp., which is available in versions for Android e iOS and can be used free of charge. 

On Android, apps like SkysafariStarchartStellarium ou Star Walk 2 can facilitate indicating the position of the comet. Although some are paid, their free versions also allow to guide the user.

Street: In The Sky/NASA/The Sun