Astronomical SIGHTS Coming to a SKY NEAR YOU!

Graphics c/o Starry Night Education

This page updated Sep 3, 2018.

See the HOME page or COMING EVENTS for daily listings.

VIS. COMETS page has more details and finder charts for currently visible comets.

The Planets for September and October 2018:

Venus is quickly dropping out of sight in the west but has a last fling on Sep 21 when it reaches maximum brightness. After that it quickly drops toward the horizon and by the end of September she is lost in the solar glare. Venus reappears as Morning Star late in October. Mercury reappears as an Evening Star in October but it is not a good apparition for Northern Hemisphere viewers.

Both of the gas giants,
Uranus and Neptune are well up in the south by dark and continue to be good viewing this fall. Neptune is at opposition Oct 21.

Jupiter has peaked and will follow Venus into the western horizon by a month or so, so some Jupiter watching is still possible. The main planets for autumn are Saturn and Mars (and Uranus and Neptune) and all are well up by dark. Saturn is sitting above the Teapot lid and changes the appearance of Sagittarius noticeably. Continue to watch Mars even though it is past maximum size and starting to shrink in diameter. The dust storm has subsided and surface details are showing through even though the disk will shrink noticeably with time.

Pluto is in Sagittarius right between Mars and Saturn and visible only in moonless sky and with larger telescopes. Finder charts are found on our CHARTS/FORMS page.

September/October 2018 Sky Sights

Jupiter well up, Saturn opposition June 27, Mars July 27
Jupiter is the first star (after Venus) to poke through twilight in the early evening after the Sun goes down. The King of Planets will be featured in several of the BAS Dark of the Moon viewing nights with the Great Red Spot visible on the planet. Saturn is next and then there is Mars, which will be the best this year than it has been since 2003.

Saturn opposition is June 27 and at magnitude 0.0 it is brightly shining to the left of the Milky Way near the lid of the Teapot. Saturn’s rings are tilted nearly the maximum they can be (26°) this summer. It will be a regular feature at summer star parties.

Mars reaches opposition July 27 and all three bright planets will be visible for much of the summer stretched along the ecliptic from SW to SE. The diameter of Mars will be steadily growing to a maximum of 24 arc seconds near opposition. This is bigger than the disk of Saturn (which ranges from 15 to 18 seconds at opposition) but not as big as Jupiter (31 to 45 seconds across). Surface features on Mars will become detectable easily this month as long as seeing is good (and there are no dust storms on the planet...) The only “fly in the ointment” this year is that Mars does not get more than 20° high above the southern horizon in Capricornus even at its best. So go out and observe often and hope for one or two nights when steady air prevails, the dust on Mars has settled (see
WEBLOG for the latest on that) and clouds don’t get in the way.

Aug 26, 2018
Mercury Farthest from Morning Sun
When Mercury rises this August morning, it will be as far from the Sun as it can get and visible in dark sky for a hour or so before the twilight blots it out. At magnitude 0, it is the brightest “star” in the morning sky once it clears the horizon just after 5 am EDT. If you can get a look through a telescope at high power, it should show a phase like a FQ moon. By the second week of September it is too close to the Sun to view but not before it sidles up to Regulus Sep 6.

Screen Shot 2018-07-27 at 1.41.58 PM

Sep 6/7/8, 2018
Mercury near Regulus and last crescent Moon
Look in the morning hours before sunup for a nice sky show before dawn involving, the Moon, Mercury and the brightest star of Leo, Regulus. The last crescent Moon sits 9° above the Beehive Cluster in Cancer on Sep 6, then 6° below M44 on Sep 7 then only 2° above Regulus on Sep 8. During the same interval, look for a -1 magnitude Mercury only 1° east of Regulus on Sep 6, and then slipping downwards to about 4° below alpha-Leo by Sep 8. It is moving back toward the Sun and will pass it in the third week of September enroute to returning to the evening sky in October.
Chart for 6:20 am EDT from Starry Night below shows the Moon on Sep 6/7/8 and Mercury’s changing position over the same interval.

Merc Moon Reg Sep 6-7-8 2018

Sep 7, 2018
Neptune at opposition
On this date, Neptune, the more distant of the two outer gas giants (the farthest official planet) reaches opposition on the same side of the Sun as Earth. In our sky it rises at sunset in the east and sets when the Sun returns to the sky at dawn. Neptune is located in Aquarius shining at magnitude 7.8 and visible in binoculars. Finder chart is found here: Neptune 2018


Sep 21, 2018
Venus maximum brightness
Venus has been slowly getting closer to us and increasing in apparent size as she does so, but the percentage of surface illuminated slowly decreases as the planet becomes more of a crescent. The two effects (decreasing illumination due to phase and increasing disk size as Venus approaches) provide for a maximum brightness on Sep 21 when Venus reaches -4.8 magnitude. Check it out but a low SW horizon is needed as the planet is sinking lower and lower in the sky.


Left: Simulation c/o US Naval Observatory Right: Istituto di Linguistica Computazionale
Galileo Galilei's observations that Venus appeared in phases -- similar to those of Earth's Moon -- in our sky was evidence that Venus orbited the sun and contributed to the downfall of the centuries-old belief that the sun and planets revolved around Earth. Also sketched here are Jupiter, Saturn and Mars.

A summary of the entire 2018 year of ASTRONOMY events can be found here:
ASTRONOMY 2018 Events
An astronomical calendar for 2018 (with diagrams of sky sights like those above) will be available soon for download from Alan Dyer's website here: (look at the bottom of the "about Alan" page).