The speedster zooms through inferior conjunction
on January 20th and swiftly enters the morning sky.
The apparent diameter of an inner planet changes appreciably with its position in its orbit; it is largest at inferior conjunction
, but since it is then between the Sun and the Earth it cannot be seen.
By contrast after Mercury has passed through inferior conjunction
on November 1, it moves west of the Sun and reaches greatest western elongation on November 18 to provide us with the best morning apparition of 2013.
Having passed through inferior conjunction
on January 20th, Mercury has migrated into the morning sky.
It is at inferior conjunction
on the 6th when it passes between the Earth and the sun.
30 Venus, at inferior conjunction
with the sun, nevertheless rises 40 minutes before sun today; first use of ether as an anesthetic, 1842, by Dr.
An inferior conjunction
of Mercury is an important astronomical phenomenon because it is an indicator to Mercury transition from an evening sky (Western horizon) to the dawn sky (eastern horizon).
The tiny planet goes through inferior conjunction
on December 13th and reappears in the morning sky around December 20th.
It then passes through inferior conjunction
on July 9 re-emerging at the end of the month into the morning sky.
Venus passes through inferior conjunction
on the 25th, when it enters the morning sky for the rest of the year.
26 Neptune at opposition (visible in binoculars, but a detailed star chart is needed to locate it among many similarly bright stars; Neptune has lost back the title of outermost planet to Pluto--and won't regain it for 230 years); Mercury at inferior conjunction
with sun and unviewable; Jupiter at west quadrature--90 [degrees] west of the sun--and hence visible in the south around dawn.
As known, there are two types of conjunction for solar system planets, Superior and Inferior conjunctions
; where Superior conjunction occurs for all solar system planets, while Inferior conjunction
occurs for two planets only (Mercury and Venus), because they orbits around the sun are inside Earth's orbit.
Mercury passes through inferior conjunction
on April 20th before reappearing at dawn at the very end of the month.
Mercury then goes through inferior conjunction
on March 4 after which it moves west of the Sun to become a morning object.
17 Mercury at inferior conjunction
with Sun (unviewable); Saturn resumes direct (that is, eastward) motion relative to the background stars.