The cosmos at our fingertips.
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orin stepanek wrote: ↑
Tue Nov 05, 2019 12:45 pm
Voyager I and II; the little engines that could!
Wow; took 42 years to travel 2/3 of a light day! So; who would want to travel to the nearest exoplanet at 4 light years away?
How are these little space probes going to fare in interstellar space with all the extra radiation?
<<2I/Borisov, originally designated C/2019 Q4 (Borisov) is the first observed interstellar comet and the second observed interstellar interloper after ʻOumuamua.
As seen from Earth, the comet is in the northern sky from September until mid-November. It will cross the celestial equator on 13 November 2019 entering the southern sky. On 6 December 2019, the comet will be an equal distance of 2 au from the Sun and Earth. On 8 December 2019, the comet will come to perihelion (closest approach to the Sun) and will be near the edge of the inner asteroid belt. In late December, it will be about 1.9 au from Earth and have a solar elongation of about 80°. Due to its 44° orbital inclination, 2I/Borisov does not make any notable close approaches to the planets.
2I/Borisov entered the Solar System from the direction of Cassiopeia near the border with Perseus. This direction indicates that it originates from the galactic plane, rather than from the galactic halo. In interstellar space, 2I/Borisov takes roughly 9000 years to travel a light-year relative to the Sun. It will leave the Solar System in the direction of Telescopium. 2I/Borisov has passed within 5.7 light-years of the binary star system Kruger 60 (13.18 light-years away, in Cepheus) at a low velocity of 3.4 km/s around a million years ago.
2I/Borisov's trajectory is extremely hyperbolic, having an orbital eccentricity of 3.3 to 3.4. This is much higher than the 300+ known weakly hyperbolic comets, with heliocentric eccentricities just over 1, and even ʻOumuamua with an eccentricity of 1.2. 2I/Borisov also has a hyperbolic excess velocity (v∞) of 32 km/s, much higher than what could be explained by perturbations, which could produce velocities when approaching an infinite distance from the Sun of less than a few km/s. These two parameters are important indicators of 2I/Borisov's interstellar origin. For comparison, the Voyager 1 spacecraft, which is leaving the Solar System, is traveling at 16.9 km/s.>>