Planets

The Planets tool tells you which planets are visible on the chosen night, when to photograph them, which settings to use with your lens or telescope, and which events mark the year (oppositions, close approaches…). It covers Mercury, Venus, Mars, Jupiter and Saturn and has three tabs: Night, Session and Calendar.

Place and date

• Place: by default, the phone’s GPS position. Tap it to search an address or enter coordinates.
• Date: the arrows move to the previous or next night, Today goes back to the current night.
• Explore the night: a strip coloured by the light of the sky, with bands showing when the Moon is up and when the chosen planet is more than 5° above the horizon.

Night tab

Choose a planet at the top of the screen:

• Visibility: from when to when it can be observed, in which direction and how high.
• Best moment: the time when it is highest in a dark enough sky. Plan opens the Planner at that time and the bell sets a reminder 15 minutes before.
• Brightness (magnitude, share lit), distance from the Earth and the Sun and, for Saturn, the tilt of the rings.
• Planets tonight: all the planets with their status (well placed, low, too close to the Sun, not visible at night). Tap one to show it.
• Clear sky in the coming nights? Once the option is on, a forecast gives the cloud cover, fog and rain while the planet is visible. It is indicative and needs a connection.
• Moments of the night: sunset, end of civil twilight, rise, culmination and set of the planet and of the Moon, civil dawn, sunrise.
• The Augmented reality button shows the planet in the real scene.

Session tab

1. Choose the planet.
2. Describe your optics: the lens focal length or, for a telescope, the aperture diameter. With eyepiece projection, enter the eyepiece and its distance to the sensor: the effective focal length is worked out.
3. The app gives:
   • the size of the planet’s disc in arcseconds and in pixels on your sensor, with an assessment: barely more than a point, small disc, or large enough to show details (belts, rings, phase);
   • the focal length needed for a disc of a given size in pixels;
   • the shutter speed, without and with atmospheric extinction, which increases when the planet is low;
   • the planet’s position at the chosen time.

When the exposure is longer than one second, a floating countdown button times it.

Calendar tab

• Visibility through the year: for each planet, the periods when it is visible in the evening, in the morning or all night, above 5° in a dark enough sky.
• Events of the year: oppositions, greatest elongations of Mercury and Venus, conjunctions with the Sun, close approaches between planets and the Moon passing near a planet. Filter by Sun, Planets or Moon. Tap an event to open its night; the bell sets a reminder 15 minutes before.

Close approach separations are computed from the Earth’s centre: for the Moon, they can vary by about one degree depending on your location.

Shooting tips

• Turbulence: moving air blurs the image. Photograph the planet when it is as high as possible, and avoid aiming above roofs and roads warmed by the Sun.
• Lucky imaging: record a video or a burst of thousands of frames, then keep and stack the best ones with dedicated software. Each short frame freezes a moment of turbulence; stacking reduces noise.
• Settings: low ISO and short exposure; focus on the planet in magnified live view.
• Equipment: a very steady tripod is enough for Venus, and for Jupiter and its moons with a telephoto lens. For details (Jupiter’s belts, Saturn’s rings), you need a long focal length, ideally a telescope on a motorised mount that tracks the sky.
• Processing: after stacking, wavelet sharpening brings out the details.