What's Up in July 2008?
By Bernie Reim
What's Up in July 2008?
By Bernie Reim
This is the first full month of summer and there are several celestial and man-made highlights to watch for to add some excitement to this new season.As the nights are already getting longer again, there are three celestial highlights to enjoy. Mars will finally catch up with and pass Saturn, Jupiter reaches opposition, and there will even be a meteor shower thrown in for good measure, the Delta Aquarids.
After racing across the sky throughout the spring, Mars will catch up with Saturn on Wednesday evening the 9th. Even before that happens, Mars will be less than one degree above Regulus on July 1, and about 4 degrees to the right, or west of Saturn. Watch closely every clear evening during the first ten days of this month to watch this much anticipated celestial drama unfold. To make it even more spectacular, a slender crescent moon will glide just underneath the trio on the evenings of Saturday the 5th and Sunday the 6th, one hour after sunset in the western sky.
Notice the different colors and magnitudes of these three objects. Golden Saturn is brightest at 0.8 magnitude, then bluish-white Regulus at 1.4, and then orange Mars is the faintest at 1.6 magnitude. Each magnitude number is a difference of two and a half times in brightness.
Mars is the closest at about 200 million miles, or just over twice the earth-sun distance. Then Saturn is nearly one billion miles away and the star Regulus in Leo is 77 light-years away. Converting these distances to light time makes Mars 17 minutes away, Saturn just over 1 hour, and Regulus 77 years. That places Regulus just over half a million times farther away than distant Saturn. When the crescent moon joins this trio, keep in mind that it is only one second away at the speed of light. So here you have a rare quartet of heavenly objects that will give you some insight into the precise mathematics of the solar system and nearby area of our Milky Way galaxy, as well as providing us with great natural beauty.
Drifting rapidly along at the rate of half a degree per day, or only 24 times slower than the moon continually moves, Mars will already be 11 degrees to the left, or east of Saturn by the end of this month. The red planet continues to fall farther and farther behind Earth in our orbit around the sun, so it continues to get smaller and dimmer in our sky.
By coincidence, Jupiter will reach opposition on Wednesday, July 9, the same day that Mars and Saturn will be at their closest until 2022. Similar to a full moon, Jupiter will be on the opposite side of the earth from the sun. That means the King of the Planets will rise at sunset, reach its highest point in the sky at midnight, and not set until sunrise. All the superior planets from Mars out to Neptune also reach the midpoint of their retrograde motion at opposition. That is the best time to view them, because they will be closest to Earth and biggest and brightest in our sky. Jupiter started its retrograde, or westward motion back on May 9th and it will switch back to direct motion in early September. Shining brightly at magnitude -2.7, Jupiter is over 6 times brighter than Saturn.
The Delta Aquarid meteor shower, caused by the earth passing through the debris trail of Comet Machholz, will only produce about 15 meteors per hour after midnight on the morning of Monday the 28th. However, you may see more than just Aquarids, because the famous Perseids will already have started, although they will not peak until August 12th.
The man-made highlights to watch for this month are the recent launch of GLAST (Gamma-ray Large Area Space Telescope) and the ongoing drama of the Phoenix mission on Mars. Launched on June 11, 8 years after our last gamma-ray space telescope was allowed to crash back to Earth after 9 years of gathering amazing data and seeing about one powerful gamma-ray burst each day, GLAST has established its communication link and is now tuning its instruments. It should be ready to start pouring in new data by the end of this month. Now we have an even better tool to study the many burning questions about the most extreme high energy environments anywhere in the universe. Its mission objectives include searching for signs of new laws of physics and what constitutes the mysterious dark matter and dark energy. It will also try to explain how black holes can accelerate immense jets of material to nearly light speed and try to answer detailed questions about solar flares, pulsars, and the origin of cosmic rays. So when you enjoy the fireworks on earth this month, keep in mind that nature is constantly producing infinitely more powerful fireworks!
When you look at Mars and Saturn this month, remember that the Phoenix lander is up there on the red planet near its North Pole and digging away into its icy soil looking for signs of life, although it hasn't found any yet.
July 2. New moon is at 10:19 p.m. EDT.
July 4. Earth is at aphelion, or farthest from the sun today. This happens every year at this time, but today we will be at the most distant aphelion of the decade and the second most distant for the whole century. This is because it occurs near new moon, so the earth has to lean a little farther out to balance the gravitational pull of the moon perfectly, just as a parent swinging a child around by its arms has to lean backwards.
July 6. Isaac Newton published his Principia, the greatest math book ever written, on this day in 1687. Mars, Saturn, and the moon form a nice conjunction this evening.
July 9. Mars and Saturn are at their closest, less than one degree apart and Jupiter reaches opposition.
July 10. First quarter moon is at 12:35 a.m.
July 14. The moon is at apogee, or farthest from Earth today.
July 16. The first fragment of Comet Shoemaker-Levy 9 hit Jupiter on this day in 1994. I remember watching 5 of those 21 fragments hitting the gas planet and leaving giant, earth-sized black marks over the course of the next 6 days.
July 17. The moon will 3 degrees south of Jupiter this evening.
July 18. Full moon is at 3:59 a.m. This is also called the Hay or Thunder Moon.
July 20. On this day in 1969 the first humans walked on the moon, still the only place other than Earth that humans have ever set foot upon. Only 12 humans have ever walked on our only natural satellite. The last two were in December of 1972. Viking 1 landed on Mars on this day in 1976.
July 25. Last quarter moon is at 2:42 p.m.
July 28. The Delta Aquarid Meteor Shower peaks today. The first photograph of a total solar eclipse was taken on this day in 1851.
Bernie Reim is an amateur astronomer from Wells, Maine who writes a monthly astronomy column for several newspapers throughout Maine. Including: The Portland Press Herald, The Kennebec Journal, The Morning Sentinel, and the York Weekly. He has also taught astronomy lab courses at the University of Southern Maine.
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