Find it in the Sky
Chose a date & time and view the position of comet C/2021 T4 (Lemmon) in the sky on our interactive planetarium.
In Evidence
Comet C/2021 T4 (Lemmon)
Comet C/2021 T4 (Lemmon) is in the constellation of Leo Minor, at a distance of
Finder Charts
The sky charts below show, at different resolutions, the position of comet C/2021 T4 (Lemmon) in the sky. Click on each chart to access the interactive star map tool.
The following map uses photographic imagery from the Digitized Sky Survey (DSS) to realistically visualize the precise position of comet C/2021 T4 (Lemmon) against the stars in the background. The horizontal size of the map measures 60 arcminutes. Click on the image to access a more detailed full-screen view.
Equatorial Coordinates
Apparent
J2000
Additional Information
The observed values of Magnitude, Coma Diameter and Tail Length are derived from the most recent observation recorded at the Comet Observers Database. The value of Predicted Magnitude comes from the JPL Horizons ephemerides service and, in the case of comets, might be inaccurate given the highly dynamic and unpredictable behavior of these objects. When available, please refer to the Observed Magnitude value and consider the Predicted 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.
Rise and Set Times
The following table lists today's rise, transit and set times of comet C/2021 T4 (Lemmon) from Greenwich, UK (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.
Distance from Earth
The distance of comet C/2021 T4 (Lemmon) from Earth is currently
The following graph shows the distance of comet C/2021 T4 (Lemmon) from Earth as a function of time. In the chart the distance is measured in Astronomical Units and the data is sampled with an interval of 1 day.
Note: The values in this chart may not be entirely accurate around the time of closest approach for objects passing very close to Earth at high speed (e.g., Near-Earth Objects).
The value of the distance of C/2021 T4 (Lemmon) from Earth is also available as a real time updated value in the live position tracker.
Closest Approach to Earth
In the period between January 1, 2000 and December 31, 2099, the closest approach of comet C/2021 T4 (Lemmon) to Earth happened on Friday 21 July 2023 at a distance of 0.541555 Astronomical Units, or 81,015,514 kilometers:
Note: the values for the closest approach are computed with a sampling interval of 1 day.
Light Curve
The following chart shows the light curve of comet C/2021 T4 (Lemmon), i.e., its apparent magnitude as a function of time. The curve is calculated using the latest ephemerides provided by JPL Horizons. The magnitude data is sampled with the interval of 2 days. Because of this sampling, inaccuracies may occur for objects that have large variations of brightness over a few days. For comets, large discrepancies can arise between the calculated brightness and the observations due to their highly dynamic, and not always precisely predictable, behavior.
Orbital Elements
The following table lists the orbital elements of comet C/2021 T4 (Lemmon) at epoch April, 13 2023 00:00 UTC (JD: 2460048.5). Source: JPL Small-Body Database
| Element | Symbol | Value |
|---|---|---|
| Orbit eccentricity | e | 0.99991819 |
| Orbit inclination | i | 160.77740884° |
| Perihelion distance | q | 1.48329798 AU 221,898,219 km |
| Aphelion distance | Q |
36,262.09015781 AU 5,424,731,485,618 km |
| Semi-major axis | a |
18,131.78672789 AU 2,712,476,691,919 km |
| Orbital period | period |
2,441,569.5804 years 891,783,289.2347 days |
| Date of perihelion transit | Tp | July 31, 2023 2,460,157.0270 JD |
| Next perihelion transit | April 18, 2443643 894,243,446.2617 JD |
|
| Argument of perihelion | peri | 329.81392999632° |
| Longitude of the ascending node | node | 257.88231220148° |
| Mean anomaly | M | 359.99995618921° |
| Mean motion | n | 0.00000040°/day |
Orbit Visualization
The following chart is a 3D animated visualization of the orbit of comet C/2021 T4 (Lemmon) relative to the other major objects in the Solar System. You can access more advanced features using our 3D Solar System Viewer.
15 Days Ephemeris
The following table lists the ephemerides of comet C/2021 T4 (Lemmon) computed for the past and next 7 days, with a 24 hours interval. Apparent celestial coordinates are provided.
| Date | Right AscensionR.A. | DeclinationDec. | MagnitudeMag | Constellation |
|---|---|---|---|---|
| Jul 05 2025 | 10h 53m 24s | +26° 16’ 17” | 20.87 | Leo Minor |
| Jul 06 2025 | 10h 53m 34s | +26° 13’ 24” | 20.88 | Leo Minor |
| Jul 07 2025 | 10h 53m 44s | +26° 10’ 31” | 20.89 | Leo Minor |
| Jul 08 2025 | 10h 53m 55s | +26° 07’ 37” | 20.90 | Leo Minor |
| Jul 09 2025 | 10h 54m 07s | +26° 04’ 43” | 20.90 | Leo Minor |
| Jul 10 2025 | 10h 54m 18s | +26° 01’ 50” | 20.91 | Leo Minor |
| Jul 11 2025 | 10h 54m 30s | +25° 58’ 57” | 20.92 | Leo Minor |
| Jul 12 2025 | 10h 54m 43s | +25° 56’ 04” | 20.93 | Leo Minor |
| Jul 13 2025 | 10h 54m 55s | +25° 53’ 11” | 20.93 | Leo Minor |
| Jul 14 2025 | 10h 55m 08s | +25° 50’ 18” | 20.94 | Leo Minor |
| Jul 15 2025 | 10h 55m 21s | +25° 47’ 26” | 20.95 | Leo Minor |
| Jul 16 2025 | 10h 55m 35s | +25° 44’ 33” | 20.95 | Leo Minor |
| Jul 17 2025 | 10h 55m 49s | +25° 41’ 41” | 20.96 | Leo Minor |
| Jul 18 2025 | 10h 56m 03s | +25° 38’ 49” | 20.97 | Leo Minor |
Additional Resources on TheSkyLive
- Comet C/2021 T4 (Lemmon): Complete reference information on TheSkyLive.com.
- Where is comet C/2021 T4 (Lemmon)?: Key information on where to find comet C/2021 T4 (Lemmon) in the sky.
- Distance of comet C/2021 T4 (Lemmon) from Earth: Find out how far comet C/2021 T4 (Lemmon) is from Earth right now.
- How Bright is comet C/2021 T4 (Lemmon)?: Current visual brightness (magnitude) and apparent size.
- Rise and Set Times: Rise and set times of comet C/2021 T4 (Lemmon) from your location.
- Interactive Sky Map: Planetarium-style interactive visualization of comet C/2021 T4 (Lemmon)'s position in the sky.
- Live Position Tracker: High precision real time tracker of comet C/2021 T4 (Lemmon)'s position using deep space imagery.
- Ephemeris: 15 days comet C/2021 T4 (Lemmon)'s computed ephemeris.
- Orbital elements: Information about comet C/2021 T4 (Lemmon) orbital parameters.
- Orbit Visualization: 3D interactive visualization showing the orbit of comet C/2021 T4 (Lemmon) with respect to the major Solar System objects.