The interstellar comet 3I/ATLAS will reach its closest point to Earth in the early morning of this Friday, December 19even if it will pass at a completely safe distance for our planet. However, its approach is of enormous scientific interest, since it is one of the rare objects from another star system detected to date.
According to the orbital calculations of the Horizons system Jet Propulsion Laboratory (JPL) from NASA, the exact moment of maximum proximity will occur at 1:00 a.m. EST, which is equivalent to 07:00 Spanish Peninsula Time. At that time, the comet will measure about 1.8 astronomical units, or about 270 million kilometersalmost double the average distance between the Earth and the Sun.
I discovered the July 1 thanks to the network of telescopes ATLASfunded by NASA and located in Chile, 3I/ATLAS is the third known interstellar object passing through our solar system, after ‘Oumuamua in 2017 and 2I/Borisov in 2019.
Although your passage carries no risk and will not be visible to the naked eyeastronomers consider this moment key to study matter formed around another starwhich makes it possible to obtain direct information on the composition and evolution of other planetary systems.
The technology needed to observe Comet 3I/ATLAS
Comet observation 3I/ATLAS need specialized astronomical instrumentationbecause its luminosity is very weak and its apparent size small. Your trajectory is monitored using data from the JPL Horizons Systemthe reference tool used by observatories around the world.
To try to detect it from Earth, experts recommend medium or large aperture telescopesof some 20 or 25 centimetersable to capture a greater amount of light. In many cases, direct visual observation is not enough, which is why we resort to CCD or CMOS astronomical camerascommon in astrophotography, which allow the comet to be recorded using long exposures.
This type of observation also requires motorized equatorial mountsessential to compensate for the rotation of the Earth and precisely follow the movement of the comet for several minutes (comets move relative to the stellar background and keeping them in the field of view during long exposures requires mounts that compensate for the Earth’s rotation). Without this tracking system, detection of such a faint object is virtually impossible.
To know exactly where to aim the telescope at any time, it is recommended to use software/apps as Stellarium, SafariSky either LeCielLivewhich offer updated ephemeris based on the position of the comet in the sky.
Added to all this is a key factor: the need for dark skies without light pollution. Even with adequate equipment, observation from urban areas is impractical. For this reason, astronomers recommend elevated areas away from urban centers.
Space missions and telescopes observing 3I/ATLAS
The stage of 3I/ATLAS for its closest point to Earthin the early morning of December 19, will be followed by a international observation campaign in which space agencies, professional observatories and scientific monitoring networks participate.
THE JAR continues to monitor the comet as part of its observation programs for small solar system bodies, using both ground telescopes as data from space missions. Its position and trajectory are precisely calculated using the JPL Horizons Systemwhich serves as a reference for observatories around the world.
At the same time, the European Space Agency (ESA) participates in the exchange of scientific data and the coordination of observations of European installations, both from Earth and from active space missions. These observations make it possible to study the evolution of the comet as it approaches and moves away from our planet.
Tracking the object is also part of the job of the International Asteroid Warning Network (IAWN)a UN-supported network that brings together space agencies, research centers and observatories from many countries. Although 3I/ATLAS poses no risk, the network coordinates observations to improve knowledge of its orbit and behavior, which is particularly relevant in the case of an interstellar object.
From space, telescopes like Hubble and other scientific instruments have already contributed to the study of the comet, by analyzing its coma and its activity. In the earthly realm, professional observatories like those linked to large astronomical facilities in the United States, Europe and Chile, continue to collect images and photometric data during these key days.
With them they also participate amateur astronomers equipped with state-of-the-art equipmentwhose data, when they meet scientific standards, are integrated into international databases and make it possible to refine orbital calculations.
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