What’s Up in the Sky October, 2007
By Peter Burkey
This month marks the 50th anniversary of the launch of the world’s first artificial satellite, Sputnik 1, an event of tremendous implications at the time. And this year marks the 30th anniversary of an event overlooked by many, yet vastly more important in terms of our understanding of the solar system – the launch of Voyagers 1 and 2.
The twin interplanetary probes, launched in the late summer of 1977, were supposed to last five years and explore only Jupiter and Saturn. Due to a rare alignment of the outer planets and marvelous work by NASA engineers, Voyager 2 was able to continue on to Uranus and Neptune and scientists continue to receive data from both spacecraft today.
They have enough thruster fuel and electrical power to last until 2020. Both are headed toward the outer boundary of the solar system, known as the heliopause, the limit of the sun’s magnetic field and solar wind. Their current mission is known as the VIM, Voyager Interstellar Mission, to study the interstellar and interplanetary media, and continue doing ultraviolet Astronomy.
The two spacecraft are currently the most distant human-made objects, with Voyager 1 holding the record at almost 10 billion miles. That is more than twice as far as Pluto. The round trip time for a radio signal is over 24 hours.
Yet we are still receiving radio transmissions from both spacecraft. Each is operating at a power level below 300 watts and transmit data at only a few watts so the signal received on Earth is miniscule – billions of times smaller than the power output of a digital watch. In fact, improved technology at the receiving end, the Deep Space Network, is one important factor that has allowed the mission to continue.
Also memorable is the Golden Record, conceived and recorded by Carl Sagan and attached to each spacecraft. The record contained 115 images and a variety of natural sounds and spoken greetings along with an eclectic sampling of music including Chuck Berry’s “Johnny B. Goode”. As Dr. Sagan said, “. . .the launching of this bottle into the cosmic ocean says something very hopeful about life on this planet.”
This month in history:
Oct. 1: First observations with 300-foot radio telescope at Green Bank, WV – 1962
Oct. 4: Sputnik 1, first artificial satellite, launched – 1957
Oct. 9: Johannes Kepler observes supernova – 1604
Oct. 13: M51 (the Whirlpool Galaxy) observed by Charles Messier – 1773
Oct. 19: Subramanyan Chandrasekhar born – 1910
Oct. 22: First recorded solar eclipse – 2136 BC
Oct. 31: Two new moons of Pluto discovered by Hubble Space Telescope – 2005
Planets this month:
– Jupiter is still bright, but sinking low in the SW.
– Mars between Orion and Gemini in predawn hours.
– Venus and Saturn dominate eastern horizon before dawn (see Oct. 7).
Oct. 3: Last-quarter Moon.
Oct. 7: Lovely gathering of Venus, Saturn, Regulus, and crescent Moon in the east 90 min. before sunrise.
Oct. 11: New Moon.
Oct. 18: First quarter Moon.
Oct. 21-22: Peak of Orionid meteors.
Oct. 25: Full Moon (the closest of the year – 221,676 miles from Earth)