Mercury

Mercury is the smallest and innermost planet in the Solar System, located 0.39 astronomical units from the Sun. It has a diameter of 4,880 kilometers and a mass of 3.3 x 10^23 kilograms, making it only slightly larger than Earth's moon. Mercury is a rocky, terrestrial planet with a heavily cratered surface and a thin atmosphere composed mostly of helium and trace amounts of other gases. The planet has a slow rotation and completes three rotations for every two orbits around the sun, resulting in a day that is longer than its year. Mercury has no moons or rings and is the second hottest planet after Venus, with a maximum temperature of 800 degrees Fahrenheit (430 degrees Celsius) on its daytime side due to its proximity to the sun. Mercury was first observed and studied by ancient civilizations, including the Babylonians and Greeks, and has been explored by multiple spacecraft in recent decades, including NASA's MESSENGER mission.

Mercury is currently in the constellation of Sagittarius.

The current Right Ascension of Mercury is 18h 08m 19s and the Declination is -25° 42’ 56” (topocentric coordinates computed for the selected location: Greenwich, United Kingdom edit_location_alt). The current magnitude of Mercury is -0.39 (JPL).

Today's rise, transit and set times of Mercury from Greenwich, United Kingdom edit_location_alt (all times relative to the local timezone Europe/London):

If you need to access this information frequently for your observations, you can create a simple customized Quick Access page, so that you can easily bookmark it in your browser favorites or add a shortcut to your mobile phones' home screen.

Available Resources

• Position and finder charts (see also Where is Mercury?)
• Distance from Earth (see also How far is Mercury from Earth?)
• When does Mercury rise and set?
• Brightness (see also How bright is Mercury?)
• Physical data. Detailed information about physical properties of Mercury, such as mass and geometric properties.
• 15 days ephemerides. Table showing celestial coordinates and magnitude of Mercury for the past and next 7 days.
• Interactive sky chart. An online planetarium application that shows where to locate Mercury in the sky from your location.
• Live position tracker. A high precision sky chart that uses real deep sky imagery to help locate Mercury with your telescope or on your astrophotographies.

Higher precision deep sky finder chart, 60 arcmin wide, showing where Mercury is right now. Click on the image to see a more detailed fullscreen tracker view.

Also check out Where is Mercury?, a page that provides all the information needed to find Mercury in the sky and additional links to sky charts.

Mercury Distance from Earth

The distance of Mercury from Earth is currently 155,066,496 kilometers, equivalent to 1.036556 Astronomical Units. Light takes 8 minutes and 37.2462 seconds to travel from Mercury and arrive to us.

The following chart shows the distance of Mercury from Earth as a function of time. In the chart the distance data is measured in Astronomical Units and sampled with an interval of 1 day.

The value of the reported distance might be somewhat inaccurate around the times of closest approach for objects passing extremely close to Earth. The value of the distance of Mercury from Earth is also available as a real time updated value in the Live Position and Data Tracker.

Closest Approach of Mercury to Earth

Between 1 January 1600 and 30 December 2499, the closest approach of Mercury to Earth happens on Mon Jun 6 2416 at a distance of 0.548876 Astronomical Units, or 82,110,662 kilometers:

NOTE: values for the closest approach are computed with a sampling interval of 1 day.

Mercury Brightness and Light Curve

The following chart is the predicted light curve (visual magnitude as a function of time) of Mercury, according to the most recent ephemerides data. Magnitude data is sampled with a 2 days interval and there might be inaccuracies for objects changing brightness very rapidly during the course of a few days. For comets there could be large discrepancies between the observed and predicted brightness because of their highly dynamic behaviour.

Mercury 15 Days Ephemeris

The following table lists the ephemerides of Mercury computed for the past and next 7 days, with a 24 hours interval. Click on each row of the table to locate Mercury in our Online Planetarium at the chosen date.

Date	Right AscensionR.A.	DeclinationDec.	MagnitudeMag	Apparent DiameterDiameter	Constellation
2023 Nov 26	17h 26m 42s	-25° 40’ 26”	-0.45	5.7”	Ophiucus
2023 Nov 27	17h 32m 39s	-25° 45’ 21”	-0.45	5.8”	Ophiucus
2023 Nov 28	17h 38m 30s	-25° 48’ 52”	-0.45	5.9”	Ophiucus
2023 Nov 29	17h 44m 15s	-25° 51’ 00”	-0.44	5.9”	Sagittarius
2023 Nov 30	17h 49m 51s	-25° 51’ 42”	-0.43	6.1”	Sagittarius
2023 Dec 01	17h 55m 18s	-25° 50’ 58”	-0.42	6.2”	Sagittarius
2023 Dec 02	18h 00m 36s	-25° 48’ 51”	-0.41	6.3”	Sagittarius
2023 Dec 03	18h 05m 39s	-25° 45’ 20”	-0.40	6.4”	Sagittarius
2023 Dec 04	18h 10m 30s	-25° 40’ 27”	-0.38	6.6”	Sagittarius
2023 Dec 05	18h 15m 02s	-25° 34’ 13”	-0.35	6.7”	Sagittarius
2023 Dec 06	18h 19m 17s	-25° 26’ 40”	-0.32	6.9”	Sagittarius
2023 Dec 07	18h 23m 09s	-25° 17’ 53”	-0.28	7.0”	Sagittarius
2023 Dec 08	18h 26m 36s	-25° 07’ 54”	-0.24	7.2”	Sagittarius
2023 Dec 09	18h 29m 36s	-24° 56’ 48”	-0.18	7.4”	Sagittarius