11° above the horizon at

sundown on

20 Nov 2024.

Oct–Nov 2024 night apparition of Mercury

The desk under lists the altitude of Mercury at

sundown
over the course of the apparition. All instances are given in Los Angeles native time.

Mercury will fade quickly in direction of the top of the apparition because it heads in direction of inferior conjunction,
when it should go between the Earth and Solar. At inferior conjunction, the planet turns its unilluminated facet
in direction of the Earth, and so seems as a skinny, barely illuminated crescent.

Since Mercury can solely ever be noticed in twilight, it’s notably tough to search out when it’s in a skinny
crescent section. Thus, it will likely be considerably simpler to see within the days earlier than it reaches its highest level
within the sky than within the days after.

Altitude of Mercury at sundown

A graph of the angular separation of Mercury from the Solar
across the time of biggest elongation is
accessible right here.

Apparitions of Mercury

Observing Mercury

Mercury’s orbit lies nearer to the Solar than the Earth’s,
that means it at all times seems near the Solar and is misplaced within the Solar’s
glare a lot of the time.

It’s observable for

only some weeks
every time it reaches biggest separation from the Solar – moments referred
to as biggest elongation.

These apparitions repeat roughly as soon as each

3–4 months,

going down alternately within the morning and night skies, relying whether or not

Mercury
lies to the east of the Solar or to the west.

When it lies to the east, it rises and units a short while after the Solar and is
seen in early night twilight. When it lies to the west of the Solar, it
rises and units a short while earlier than the Solar and is seen shortly earlier than
dawn.

Nevertheless, some instances of the yr are extra beneficial for viewing Mercury than others. From Los Angeles, it reaches
a peak altitude of between

11°

and

22°

above the horizon at sundown
throughout every night apparition,
relying on the time of yr. Throughout its Oct–Nov 2024 apparition,
it should peak at

11° above the horizon at

sundown on

20 Nov 2024.

This variability over the course of the yr is because of a mix of two components.

The inclination of the ecliptic to the horizon

Always, Mercury lies near a line throughout the sky
referred to as the ecliptic, which is proven in yellow within the planetarium above. This line
traces the trail that the Solar takes by the zodiacal constellations yearly, and
reveals the airplane of the Earth’s orbit across the Solar. Since all of the planets circle the
Solar in virtually precisely the identical airplane, it additionally intently follows the planes of the orbits
of the opposite planets, too.

When Mercury is extensively separated from the Solar, it’s separated from it
alongside the road of the ecliptic. However, at completely different instances of yr, the ecliptic meets the horizon
at completely different angles at sundown. Which means
Mercury seems at completely different
altitudes above the horizon at completely different instances of yr, even when its separation from the Solar is identical.

If the ecliptic meets the horizon at a shallow angle, then Mercury must be very extensively
separated from the Solar to seem a lot above the horizon. Conversely, if the ecliptic is sort of perpendicular
to the horizon, Mercury might seem a lot larger within the sky, even whether it is
really a lot nearer to the Solar.

At sundown, the
ecliptic makes its steepest angle to the horizon on the spring equinox – in March
within the northern hemisphere, and in September within the southern hemisphere. Conversely, it meets the horizon at its
shallowest angle on the autumn equinox. As a result of the seasons are reverse within the northern
and southern hemispheres, a great apparition of Mercury in a single hemisphere will normally
be poorly positioned within the different.

At dawn, these dates are additionally inverted, in order that for morning apparitions of Mercury,
the ecliptic makes its steepest angle to the
horizon on the autumn equinox, and its shallowest angle to the horizon on the spring equinox.

Mercury’s elliptical orbit

A secondary impact is that
Mercury is uncommon among the many planets for having a considerably non-circular orbit, which
varies in its distance from the Solar by 52% between its closest strategy
(perihelion, labelled P within the diagram to the fitting) and biggest distance (aphelion, labelled A).

Which means Mercury’s separation from the Solar at biggest elongation varies, relying the place it lies
relative to the aphelion or perihelion factors of its orbit. In mid-September and mid-March, the Earth is nicely positioned
to view the lengthy axis of Mercury’s orbit edge-on.

So, if Mercury seems within the night sky in
mid-September, or within the morning sky in mid-March, then it seems extra extensively separated from the Solar
than typical. Particularly, at every apparition, Mercury reaches a separation from
the Solar of between 18 and 28°. Throughout its Oct–Nov 2024 apparition,
it should attain a most separation of

22°
to the Solar’s east at biggest elongation.

The optimum time for an apparition of Mercury

The 2 results described above are of comparable magnitude, although the inclination of the ecliptic
to the horizon is the extra
vital. They conspire to make Mercury a lot simpler to
observe from the southern hemisphere than from the north.

Within the southern hemisphere, apparitions of Mercury which happen when the ecliptic airplane is favourably
inclined to the horizon additionally coincide with apparitions when Mercury is near aphelion. Within the northern
hemisphere, sadly the alternative is true: when the ecliptic airplane is favourably inclined, Mercury
is near perihelion.

The plot to the fitting reveals the utmost altitude of Mercury throughout all its

night
apparitions between 2000 and 2050,
as noticed from a variety of various latitudes on Earth.
The very best altitudes are seen completely from the southern hemisphere.

Mercury’s place

The place of Mercury when it reaches biggest elongation will likely be:

The coordinates above are given in J2000.0.

The sky
on 16 Nov 2024

Supply

The circumstances of this occasion have been computed utilizing the DE430 planetary ephemeris revealed by the Jet Propulsion Laboratory (JPL).

This occasion was routinely generated by looking out the ephemeris for planetary alignments that are of curiosity to newbie astronomers, and the textual content above was generated primarily based on an estimate of your location.

Associated information

Picture credit score

© NASA/JPL/MESSENGER