Observing Forecast
The evening forecast for this Friday, October 10th is clear.
Forecast provided by Clear Sky Clocks.
Clouds are not the only kind of weather skygazers have to worry about. If the air between the telescope and the object is turbulent enough (a condition astronomers call bad seeing), the image will shimmer and blur. Planets tend to be most affected by bad seeing, stars or open star clusters the least. Clear Sky Clocks can predict bad seeing a day or two in advance.
Now Visible
This a list of the major types of objects visible in the sky over the coming weeks. It is neither an exhaustive listing nor a guarantee that we will see everything described here.
Planets
Throughout the course of the year, all of the major Planets can be viewed from the Fuertes Observatory.
Currently, Jupiter, appearing in the constellation Ophiuchus, dominates the southwestern sky during the early evening hours. At -2.2 Magnitude, it is easily visible to the naked eye, appearing brighter than any stars. When view through the telescope, Jupiter's four largest 'moons', can be seen orbiting the planet on any given night.
To the persistent and skilled observer, Mercury is visible through binoculars very low in the western sky immediately following sunset.
Neptune and Uranus can be viewed later in the evening, but at magnitudes 7.8 and 5.7, respectively, they are only visible through the telescope.
Mars rises around midnight, shining brightly orange (at magnitude +0.3) high in the predawn sky. It will make its way into our night sky late this fall in the constellation of Taurus, and will be well placed for excellent evening viewing by winter.
Saturn is not long behind it, at the moment just visible at +0.6 magnitude near dawn in the constellation Leo, below the brilliant "morning star" Venus, which, at -4.4 magnitude, is at its brightest for the year. While Saturn rises earlier each night, eventually making its way into our evening skies by spring, Venus will remain shining brilliantly in the morning sky for the next six months.
Orionid Meteors
Every few seconds, a particle of interstellar dust runs into the Earth's atmosphere and burns up, producing a streak of light known as a meteor; you can count on seeing a few on a typical night. Between October 20 and 24, however, the Earth passes very close to the orbit of Comet 1P/Halley. As our planet plows through debris left behind by the comet, observers can hope to see several meteors per hour in the Orionid meteor shower. The Orionids, despite their famous source, are not particularly bright. Like most meteors they are easier to spot in the early morning rather than the evening.
The Orionid shower is so called because its meteors seem to come from the direction of the constellation Orion, but few actually extend back that far. For the best chance of seeing a meteor, look some distance away from Orion. Or, better yet, don't look in any specific direction. Because of how human perception works, the less you focus on a spot and actually search for meteors, the more likely you are to catch one out of the corner of your eye.
Double Stars
Unlike our Sun, over half of the stars in the Galaxy are found as pairs or triplets in orbit around each other. Most of these systems can only be observed indirectly, but the individual members of a handful of doubles are far enough apart that you can see them through a telescope. Albireo and γ Andromedae are two Fuertes favorites well known for their contrasting colors. What ε Lyrae, another popular target, lacks in color it makes up for in quantity, with four stars all orbiting each other.
Some famous double stars (such as Alcor and Mizar, in Ursa Major) are not actually orbiting each other — they are two separate stars that just happen to lie in nearly the same direction, at different distances.
Star Clusters
Star clusters are a common Fuertes target throughout the year. Clusters come in two types. Open clusters are groups of newly formed stars. They are typically within a few thousand light years of the Earth and appear through the telescope as a dense collection of a few dozen to a few hundred stars. What you are actually seeing are only the brightest cluster members; most of the stars are too faint to see except in photographs.
Globular clusters are groups of up to a million stars that (with a few exceptions) date from the formation of the Galaxy. They tend to be 10-50,000 light years away and appear through the telescope as fuzzy balls. You can make out individual stars only on the outskirts; farther in there are far too many to tell apart. The night sky of a planet in one of these clusters would have thousands of bright stars (some brighter than our Moon), and a sky that never grows darker than our twilights.
Planetary Nebulae
When fairly small stars, such as the Sun, end their lives, their outer layers detach to form an expanding shell of gas called a planetary nebula. Planetary nebulae typically last a hundred thousand years (much longer than recorded history, but almost nothing on cosmological timescales) or less before they fade into interstellar space. The Ring Nebula is the nicest example of a planetary nebula, and one we will be observing very often during the summer and early fall. Though it's too faint to see through the Fuertes telescope, the center of the nebula contains a white dwarf - the remains of the star's core, still glowing with left-over heat.
Galaxies
While galaxies come in a range of shapes and sizes, the ones that you can easily spot through the Fuertes telescope are all fairly large (the size of the Milky Way or larger) and appear to the eye as elliptical blobs. Some galaxies do have spiral arms, of course, but those are usually hard to see even with a telescope much larger than ours. Arms and other subtle features usually show up only in long exposure photographs.
The Andromeda Galaxy (officially called M 31) is the nearest large galaxy to the Milky Way, only 2.5 million light years away. In dark skies it can be spotted with the unaided eye, but the Ithaca area is usually much too bright for it to be visible without at least binoculars.