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Comet C/2017 S7 (Lemmon)

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Comet C/2017 S7 (Lemmon) Position

Comet C/2017 S7 (Lemmon) is currently in the constellation of Fornax. The current Right Ascension is 02h 51m 33s and the Declination is -31° 41’ 56”.

02h 51m 33s
-31° 41’ 56”

Simplified sky chart showing where Comet C/2017 S7 (Lemmon) is right now in the sky with respect to the brightest stars and constellations (see full screen Online Planetarium)

Map showing Comet C/2017 S7 (Lemmon) in Fornax on February, 25 2020
Field of view: 60x30 degrees
View fullscreen
 = visible to the naked eye
 = binocular, brighter than 10th magnitude
= current altitude ≥ 30°   = current altitude < 30°   = below the horizon
Location: Greenwich, United Kingdom [change]

Higher precision deep sky finder chart showing where Comet C/2017 S7 (Lemmon) is right now (view fullscreen)

C/2017 S6 (Lemmon)
RA: 02h 51m 33s
Dec: -31° 41’ 56”
Deep sky finder chart for Comet C/2017 S7 (Lemmon)
Field of view: 60x40 arcmins
View fullscreen

Also check out Where is Comet C/2017 S7 (Lemmon)?, a page that provides all the information needed to find Comet C/2017 S7 (Lemmon) in the sky and additional links to sky charts.

Comet C/2017 S7 (Lemmon) Distance

The distance of Comet C/2017 S7 (Lemmon) from Earth is currently 1,520,103,554 kilometers, equivalent to 10.161265 Astronomical Units. Light takes 1 hours, 24 minutes and 30.5197 seconds to travel from Comet C/2017 S7 (Lemmon) and arrive to us.

1 hours, 24 minutes and 30.5197 seconds

The following chart shows the distance of Comet C/2017 S7 (Lemmon) 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.

Distance of Comet C/2017 S7 (Lemmon) from Earth between January 2013 and December 2100

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 C/2017 S6 (Lemmon) from Earth is also available as a real time updated value in the Live Position and Data Tracker.

Closest approach of Comet C/2017 S7 (Lemmon) to Earth

Between January 2013 and December 2100 the closest approach of Comet C/2017 S7 (Lemmon) to Earth happens on Sun Dec 18 2016 at a distance of 6.69809167 Astronomical Units, or 1,002,020,253 kilometers:

Sun Dec 18 2016

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

Comet C/2017 S7 (Lemmon) brightness

The current visual magnitude of Comet C/2017 S7 (Lemmon) is 21.63.


The observed magnitude and coma diameter values are derived from the Comet Observers Database by averaging the values reported in recent observations (more recent than 4 days), when available. The Estimated Magnitude comes from the JPL Horizons ephemerides service and might be inaccurate given the highly dynamic and unpredictable behavior of comets. When available, please refer to the Observed Magnitude value and consider the Estimated Magnitude as a directional indication. We acknowledge with thanks the comet observations from the COBS Comet Observation Database contributed by observers worldwide and used in this table to report recent comet observations.

The following chart is the predicted light curve (visual magnitude as a function of time) of Comet C/2017 S7 (Lemmon), 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.

Predicted magnitude of Comet C/2017 S7 (Lemmon) between January 2013 and December 2100

Comet C/2017 S7 (Lemmon) rise and set times

Location: Greenwich, United Kingdom [change]
Latitude: 51° 28’ 47” N
Longitude: 0° 00’ 00” E
Timezone: Europe/London

Today's Comet C/2017 S7 (Lemmon) rise, transit and set times from Greenwich, United Kingdom [change] are the following (all times relative to the local timezone Europe/London):

Azimuth: 121.7°
Max altitude: 6.8°
Azimuth: 238.3°
Comet C/2017 S7 (Lemmon) is below the horizon from Greenwich, United Kingdom

The rise and set times are defined as the time at which the upper limb of Comet C/2017 S7 (Lemmon) touches the horizon, considering the effect of the atmospheric refraction. As the atmospheric conditions cannot be modeled precisely the times reported here should be considered correct with an approximation of few minutes.

Comet C/2017 S7 (Lemmon) Orbital Elements

The following table lists the orbital elements of Comet C/2017 S7 (Lemmon) at epoch 16 November 2017 00:00 UTC (JD: 2458074.5). Source: JPL Small-Body Database

Element Symbol Value
Orbit eccentricity e 1.00250628
Orbit inclination i 124.22477833°
Perihelion distance q 7.61440680 AU
1,139,099,047 km
Aphelion distance Q n.a.
Semi-major axis a n.a.
Orbital period period n.a.
Date of perihelion transit Tp 2017-May-27 21:03:37
2,457,901.3775 JD
Argument of perihelion peri 187.74678357635°
Longitude of the ascending node node 262.78842728771°
Mean anomaly M 0.001018936952627°
Mean motion n 0.00000589°/day

Visualization of Comet C/2017 S7 (Lemmon) Orbit

This 3d orbit diagram is a feature of our 3D Solar System Simulator and shows the orbit of Comet C/2017 S7 (Lemmon) with respect of the Sun and the orbits of the major planets. The position of Comet C/2017 S7 (Lemmon) and the planets along their orbits in this diagram accurately represents the current configuration of the objects in the Solar System. This is an experimental feature and it requires a WebGL enabled browser. Please provide us feedback!

Orbit Diagram of Comet C/2017 S7 (Lemmon)
View Comet C/2017 S7 (Lemmon) in the 3D Solar System Simulator

Comet C/2017 S7 (Lemmon) 15 Days Ephemeris

The following table lists the ephemerides of Comet C/2017 S7 (Lemmon) computed for the past and next 7 days, with a 24 hours interval. Click on each row of the table to locate Comet C/2017 S7 (Lemmon) in our Online Planetarium at the chosen date.

Date Right AscensionR.A. DeclinationDec. MagnitudeMag Constellation
2020 Feb 18 02h 51m 23s -32° 01’ 54” 21.60 Fornax
2020 Feb 19 02h 51m 23s -31° 59’ 12” 21.60 Fornax
2020 Feb 20 02h 51m 23s -31° 56’ 29” 21.61 Fornax
2020 Feb 21 02h 51m 24s -31° 53’ 45” 21.61 Fornax
2020 Feb 22 02h 51m 24s -31° 51’ 03” 21.62 Fornax
2020 Feb 23 02h 51m 26s -31° 48’ 23” 21.62 Fornax
2020 Feb 24 02h 51m 29s -31° 45’ 42” 21.63 Fornax
2020 Feb 25 02h 51m 32s -31° 43’ 03” 21.63 Fornax
2020 Feb 26 02h 51m 34s -31° 40’ 23” 21.64 Fornax
2020 Feb 27 02h 51m 38s -31° 37’ 45” 21.64 Fornax
2020 Feb 28 02h 51m 42s -31° 35’ 08” 21.64 Fornax
2020 Feb 29 02h 51m 46s -31° 32’ 34” 21.65 Fornax
2020 Mar 01 02h 51m 51s -31° 29’ 58” 21.65 Fornax
2020 Mar 02 02h 51m 56s -31° 27’ 25” 21.66 Fornax