THE USM SOUTHWORTH PLANETARIUM
207-780-4249 www.usm.maine.edu/planet
70 Falmouth Street Portland, Maine 04103
43.6667° N 70.2667° W
Altitude: 10 feet below sea level
Founded January 1970
Julian date: 2458623.5
"Made from the best stuff off Earth
THE DAILY ASTRONOMER
Monday, May 20, 2019
The Upcoming Mercurian Transit
is immensely important to us because it will be the last transit of
Mercury we'll
observe here for the next thirty years! Or, to be a little more precise,
the next 29.5 years. If you miss the November 11, 2019 transit of Mercury,
you won't have another opportunity to observe one here in the eastern
United States until May 2049. Now, if you don't mind traveling to other
parts of Earth, you could observe a transit in either 2032 or 2039. In
fact, if you don't mind traveling to other spots in the solar system, you
could see a transit of Mercury right now!*
A transit of Mercury occurs when the planet moves directly in front of the
Sun with respect to us. As the previous transit occurred in May 2016, we
can hardly complain that we're about to experience a dearth of Mercurian
transits.** Moreover, Mercury describes a long path across the Sun
during the November 2019 event, providing us with ample time to observe the
transit:
[image: tm2019-Fig01b.gif]
*Mercury's path across the Sun *During the November 11, 2019 transit,
Mercury will follow such a long path across the Sun that the planet will
remain visible for nearly five and half hours! As we eastern American
observers won't observe another transit until May 2049, this event will
afford us ample opportunity to see the first world's shadow against Sol.
Throughout the next few months, we'll return to this transit with more
detailed information. (We'll also post and distribute a free module, as
well.) For now, we'll restrict ourselves to some basic information and
questions.
The transit will occur on November 11, 2019.
For we few, we happy few in Portland, the transit will begin at 7:36 a.m.
Mid transit occurs at 10:20 a.m. and the transit ends at 1:04 p.m. for a
transit duration of 5 hours and 28 minutes. The times will vary only
slightly in other New England and eastern American locations.
Do note that the transit beginning time refers to first contact. Mercury
first appears to touch the Sun's edge at 7:36 a.m. The entire planet be
visible against the Sun about 1 - 2 minutes later.
*WILL I NEED EYE PROTECTION?*
One always needs eye protection to observe the Sun. However, Mercury will
appear so small that one will only be able to observe the transit with a
telescope equipped with special filters.***
*WHAT DO I DO IF I DON'T HAVE A TELESCOPE?*
Simple. Weather permitting, the Southworth Planetarium will have at least
one telescope available through the entire transit. You can also contact
your local astronomy society. As this will be the last transit we
eastern Americans will see for three decades, it is very likely that
astronomy societies will be organizing events around this transit.
*THIRTY YEARS IS A LONG TIME! WILL A TRANSIT OF VENUS HAPPEN ANYTIME SOON?*
Even though the next transit of Mercury that we'll see here won't happen
until 2049, the next transit of Venus isn't slated to happen until December
11, 2117. In fact, eastern American observers won't actually see that
event. They will see the transit of Venus that will happen on December 8,
2125!
*WHY SHOULD WE CARE?*
I love this question because we astronomy people hear it constantly. Fact
is that yes, this event will prove to be utterly unimportant to many good
people who are leading rich and joyous lives. We care because physical
reality is inherently fantastic and we love to watch worlds in motion in
real time.
I must ask, however, if Patriots coach Bill Belichick rode in on a moon
beam to address an audience in Portland, would anybody in the congregation
ask, 'Why should we care about this? Football is only a game."
[Inquisition: the Southworth Planetarium has changed its address to
Central Park West at 79th Street New York, NY 10024.]
*HUH?
I know. It sounds like just another silly statement we tend to write in
these articles. A transit occurs when a planet appears to move in front
of the Sun. Well, as Mercury is always moving around the Sun, if you
position yourself in the right place at any given time, you can observe
Mercury moving directly across from the Sun whenever you wish to do so.
Transits of Mercury and Venus are rare because, well, Earth has to be in
the right place relative to either planet for a transit to occur. If we
could zip around the solar system and occupy any point we wanted, we could
binge watch planetary transits.
**Presently, 3.5 years is the least amount of time that will elapse between
successive transits. It is fortunate that we were able to observe the
2016 event and provided the skies are clear, we'll be able to watch the
entire November 2019 event, as well.
***Such protective filters include aluminized mylar shielding that can be
placed on the telescope end. If you have an eyepiece with a protective
filter, please do me a favor: place it on the ground and take a
sledgehammer to it! You see, one should NEVER trust a filter that is
placed on the telescope component where the light focuses! Yes, it might
work, but if it doesn't, that focused sunlight is going to burn right into
your eye! The mylar shielding is much better on at the end of the
telescope where the light enters. It is better still to project the
sun's image onto a surface so as to avoid irreparable eye damage
altogether.
|
