From both values of the position of the nodes it is clear that possible impacts of the asteroid (101955) Bennu with the earth can occur close after present time, according to the run of the position of the ascending node, and maybe after 1000 yr in the future according to the position of the descending node
. These prognostic dates of possible impact are based on the mean value of both positions of nodes not for individual possible impactors (VAs).
For example, the 8-year pair of transits in 2004 and 2012 both occur at Venus' descending node
, with the Sun looking down on June flowers in Earth's Northern Hemisphere.
Comet Giacobini-Zinner returns to perihelion on 2012 February 11 and reaches the descending node
6.06 days later on February 17.
For an eclipse to occur, the line between these two nodes -- which itself rotates with a period of 347 days (the so-called eclipse year) -- must intersect the sun at a time when the moon, in its own orbit, is sufficiently close to either the ascending or descending nodes
. If it is then between the earth and the sun, then a solar eclipse results.
In the present case Venus reaches inferior conjunction on June 6d 1h, passing through the descending node
at 17h, just sixteen hours later.
The ascending and descending nodes
of the Moon's orbit--its intersections with the Sun's path across our sky--were traditionally known as the dragon's head and dragon's tail.
The orbit comes close to that of the Earth and it could produce a meteor shower at the descending node
The very brightest oppositions of Vesta are those that take place at its descending node
, around July 5th, when it reaches magnitude 5.2.
It is rooted in Hindu astronomy and astrology, which regarded the invisible nodes as a pair of graha, or planetary divinities, known as Rahu (the ascending node) and Ketu (the descending node
The closest approach of the orbit of the asteroid to the orbit of the earth occurs near the descending node
, at a distance of about 4,600,000 miles.
* Earth closely follows Giacobini-Zinner to the comet's descending node
(where Earth passes through the comet's orbital plane).
Argument of perihelion 43.63720 [degrees] Longitude of ascending node 126.37563 [degrees] Eccentricity 0.5147984 Inclination 19.81182 [degrees] Currently the ascending node is between the orbits of Mercury and Venus, and the descending node
between the orbits of Earth and Mars.
While the Moon closets itself in the Earth's shadow at the ascending node of its orbit this month, the Sun is occupying the descending node
on the opposite side of the sky in Pisces, the Fishes.