As November begins, two of the solar system’s rocky planets form a nice pair low in the western sky during twilight. They add a sparkle to our view of the constellation Scorpius the Scorpion as it sinks toward the horizon.
Innermost Mercury comes into view first. It shines at magnitude –0.1 and appears 8° directly below 1st-magnitude Antares on Nov. 1. The planet approaches within 4° of the Scorpion’s brightest star during the month’s second week.
Mercury looks even better when you view it through a telescope. As it moves closer to the Sun in advance of its Nov. 20 inferior conjunction, the inner world shows a beautiful crescent during moments of good seeing. The best viewing time comes around the 12th, when the planet’s disk spans 9″ and appears 22 percent lit.
Ruddy Mars joins Mercury in evening twilight during the first half of November. The two reach conjunction on the 12th, when Mercury slides 1.3° south (upper left) of Mars. The two make a fine sight along with Antares, and all three will fit in a single binocular field. Don’t confuse the Red Planet with the red supergiant Antares. Magnitude 1.4 Mars lies below the star and appears a bit dimmer.
Turn a telescope on Mars and you’re sure to be disappointed. It lies on the far side of the solar system from Earth and looks tiny, with an apparent diameter of just 4″. Both Mars and Mercury disappear into the solar glare after midmonth.
Once darkness falls and Mercury and Mars have vanished, turn your attention to the north. There you’ll find Saturn located about two-thirds of the way from the horizon to the zenith. The ringed planet shines at magnitude 0.8, easily the brightest object in the so-called water constellations that cover much of our spring evening sky. Saturn lies in the north-eastern corner of Aquarius the Water-bearer, just across that constellation’s border with Pisces the Fish.
A telescope transforms the planet from a bright point of light into a stunning world. Saturn’s disk measures 19″ across in mid-November while the ring system spans 42″. You might have a hard time discerning the rings, however, because they tilt a minuscule 0.4° to our line of sight. Use the minimal glare from the rings to look for subtle details in the gas giant’s atmosphere as well as several of the planet’s moons.
You’ll have to wait several hours for the next planet to appear, but it’s worth the delay. Jupiter rises among the background stars of Gemini the Twins, to the south (upper right) of the constellation’s two brightest stars, Castor and Pollux. At magnitude –2.4, the giant planet outshines all stars, including brilliant Sirius. Jupiter begins retrograde (westward) motion Nov. 11, heralding its upcoming opposition in January.
Wait until the planet climbs higher as dawn approaches before turning your telescope in its direction. With an equatorial diameter of 42″ in mid-November, the gas giant’s disk should show a wealth of detail under steady seeing conditions. The smallest instruments also reveal the planets four bright Galilean moons.
Although Venus is the brightest planet, it is essentially unobservable this month from mid-southern latitudes. The planet begins November 16° west of the Sun, but it stands just 2° above the eastern horizon 30 minutes before sunrise. The inner planet will return to view on March evenings.
The starry sky
If you look high in the north late on any November evening, you’ll spot the sprawling constellation Cetus the Whale. This star pattern holds a single Messier object, the Squid Galaxy (M77), and it’s worth exploring with a telescope.
French astronomer Charles Messier (1730–1817) compiled a list of non-stellar objects more than two centuries ago. His only interest was in finding comets — he discovered 13 independently — so he wanted to catalog those objects observers could mistake for comets. The Squid Galaxy became the 77th entry in his catalog.
Of course, no one recognized galaxies for what they were in Messier’s time. Indeed, the great astronomer recorded the object as a “cluster of stars,” even though he could not possibly have resolved any part of M77. He would have seen the object as a patch of light, as you will when you first set eyes on it. Look for M77 0.9° east-southeast of 4th-magnitude Delta (δ) Ceti. Once you have Delta in the middle of an eyepiece field, nudge the scope 20′ south and wait a bit more than three minutes. M77 will then lie at the center of the field.
At 9th magnitude, the galaxy makes a fine target for relatively small scopes. A 7.5cm instrument is enough to spot it, but it appears better with greater aperture. The galaxy shows up easily because it has a concentrated central region.
M77 is a Seyfert galaxy — an active galaxy with a bright nucleus that emits strongly across a broad range of wavelengths. The radiation comes from an accretion disk surrounding a central supermassive black hole. It’s the same process that powers quasars, but, unlike quasars, the galaxy itself shows up clearly.
Interestingly, M77 recently “migrated” across the celestial equator. In standard epoch 2000.0 coordinates, M77’s center lies just 48″ south of the celestial equator. But in the 25 years since, precession has carried the galaxy through the equator to the northern side. Its slowly changing declination current stands at 6′ north.
Interestingly, M77 recently “migrated” across the celestial equator. In standard epoch 2000.0 coordinates, M77’s center lies just 48″ south of the celestial equator. But in the 25 years since, precession has carried the galaxy through the equator to the northern side. Its slowly changing declination current stands at 6′ north.
Star Dome
The map below portrays the sky as seen near 30° south latitude. Located inside the border are the cardinal directions and their intermediate points. To find stars, hold the map overhead and orient it so one of the labels matches the direction you’re facing. The stars above the map’s horizon now match what’s in the sky.
The all-sky map shows how the sky looks at:
11 p.m. November 1
10 p.m. November 15
9 p.m. November 31
Planets are shown at midmonth here.