If you take a stroll out in early October and gaze low in the southern sky, you'll see two reddish objects. One is Mars, the other is Antares. They both look like stars, but only the one on the right, Antares, is a star. The other is a planet.

Antares resides in the constellation Scorpius the Scorpion. Scorpius is one of the zodiac constellations along the ecliptic (the apparent path of the Sun across the background stars.) The planets appear to move along the ecliptic also and so sometimes, like now, Antares and Mars appear close to each other. The ancient Greeks gave Antares its name, which literally means the "rival of Mars." The Chinese described Antares as the "Fire Star. "

Antares is a red supergiant, an elderly bloated star 700 times larger than our Sun. It is so large that if it were placed where our Sun is, the Earth would be inside the star's atmosphere! In order for the Earth to still be a life bearing planet, it would have to move beyond the orbit of Pluto.

If you have the stamina for it, you can see the entire planet of Jupiter in one night this month! Jupiter is the largest planet in the solar system, containing 71 percent of the entire mass of all the planets. It is 11 times larger than Earth, if Jupiter were the size of a dinner plate, the Earth would be the size of a dime! Jupiter also holds the speed record for rotation in the solar system, spinning once on its axis every 9.8 hours as opposed to Earth's 24 hour rotation. This month Jupiter remains in the sky for over 12 hours, which means that you could see the entire surface of the planet if you periodically peeked through the telescope or binoculars all night long.

As Jupiter swings around the Sun in its orbit, it periodically is positioned directly opposite the Sun from the Earth. All three are in a straight line and Jupiter is at what we call opposition. Once every twelve years, Jupiter is both at its closest point to Earth (perihelion) and opposition. It is hard not to notice Jupiter as it rises in the east after sunset. A small telescope will show four of Jupiter's moons and surface features on the planet including the over 300 year old storm which we call the great Red Spot.

Rising about 40 minutes after Jupiter is the ringed planet Saturn. Saturn is approaching opposition next month but is not as bright as Jupiter. The two giant planets are about 15 degrees apart, roughly the width of your hand held at arms length. But what Saturn may lack in brightness, it makes up for with the splendor of its rings. The rings are tilted at about a 20 degree angle relative to Earth and make for easy viewing.

Saturn is like a giant snowball in space, composed of hydrogen and helium ices and gasses . It is the least dense of all the planets. Water has a density of 1.0, Saturn has a density of 0.69. This means that is you could take a chunk of Saturn and bring it back to Earth, it would float in a pool of water!

Saturn has over 16 moons, and it hosts Titan, the second largest moon in the solar system (Jupiter's Ganymede ranks and number one.) Titan is larger then the planet Mercury, and the only moon of hold a substantial atmosphere composed mostly of Nitrogen. A small telescope will show Titan but it will take at least a six inch scope to show more moons.

If you are an early morning riser, or have stayed up to view Jupiter all night, you can top off the night's viewing with Venus. Unless you have looked at Venus in binoculars or a small telescope, you would not know that this planet goes through phases similar to our Moon. In the beginning of the month, Venus is a thick crescent, by the end of the month, when the planet has reached its maximum apparent distance from the Sun, it will have moved into a half full phase.

Full moon is on the 24th and this month's moon is called the Hunter's moon. Happy planet hunting!

Constellations

The Solar System