What's Up in June 2008?
By Bernie Reim
What's Up in June 2008?
By Bernie Reim
Summer always begins around the third week of June for the Northern Hemisphere. This year the summer solstice will happen at 7:59 p.m. EDT on Friday, June 20th. That is the earliest that summer has started for over 100 years, since 1896.The word solstice means "sun stands still", which is what it appears to be doing at the apex of its trip through the sky. For us at this latitude of about 43 degrees north, that means the sun will rise well north of east, reach nearly 70 degrees high in the sky when it crosses the meridian at high noon, and set well north of west 15 and a half hours later. By contrast, the sun only reaches about 25 degrees in the sky and rises and sets well south of east and west on the winter solstice, when the days are less than 9 hours long and the sun reaches its lowest point on December 21st.
Not only do we experience the shortest night of the year on the summer solstice, we also experience the longest twilights of the year, because the angle of the sun to the horizon is not as steep as in winter.
There are three dimensions of twilight; civil, when you can still read a book outside, nautical, when it is dark enough for some of the brighter stars to appear that are commonly used in navigation, but still light enough to see the horizon, and then astronomical twilight, when most people think it is already dark, but if you look closely you will notice that the Milky Way galaxy still looks washed out. Each division of twilight is defined by the sun reaching another 6 degrees below the horizon.
On the summer solstice the sun will set at 8:25 p.m., civil twilight ends at 9:01, nautical twilight at 9:48, and astronomical twilight doesn't end until 10:48 p.m. It is not completely dark until the sun reaches 18 degrees below the horizon. As you go farther north, some parts of the earth will never get beyond one of those phases of twilight all night long near the summer solstice. That is why Scandinavia is known as the land of the midnight sun. If you travel farther north into Greenland and parts of Canada, you will not see any phase of twilight at all at this time. The most extreme case is the North Pole, which experiences 6 months of daylight in summer and 6 months of night in winter.
Even for us at this latitude, astronomical twilight already begins at 2:37 in the morning, so our true night is less than 4 hours long on the summer solstice.
The nights may be very short now, but there is plenty of planetary action to observe during those short nights. Mars continues to rapidly catch up with Saturn at the rate of half a degree per day. The red planet begins the month 18 degrees to the west of Saturn and Regulus, the white star just to the right of the slightly brighter golden planet, but ends the month less than one degree above Regulus and 5 degrees west of Saturn. Keep watching this pair of contrasting planets into next month, when they will pass within less than one degree of each other on July 9. Notice the differences in their brightness and color. Golden Saturn is one magnitude, or two and a half times brighter than Mars is now.
As if to highlight and point out the rapid approach of Mars and Saturn, the waxing crescent moon will pass just one degree below Mars on the evening of Saturday, June 7, and it will pass just below Regulus, next to Saturn, the next evening. The moon constantly moves eastward at the rate of 12 degrees per day.
Jupiter keeps rising a little earlier each evening approaching its July 9 opposition, when it rises at sunset and doesn't set until sunrise. As June begins, the King of the Planets rises around 11 pm, but it will rise just half an hour after sunset by the end of the month, softly glimmering into view in the southeastern sky just as nautical twilight begins.
Watch the nearly full moon around 11 pm on June 16 as it passes directly below Antares, the brightest star in Scorpius, and one of the largest stars in our whole galaxy of 200 billion stars. Antares, which means "rival of Mars", is a red supergiant star that is 700 times larger than our sun. So if you place Antares where our sun is located in the sky, all 4 terrestrial planets, from Mercury through Mars, would be orbiting inside its surface! It would even extend beyond the asteroid belt, nearly all the way to the planet Jupiter. Then keep watching the moon as it drifts through Sagittarius and just below Jupiter on the 19th. This is also the best time of year to watch Antares, since it rises at sunset and stays in the sky all night long, but it never gets very high in the sky for us at this latitude.
As you watch the full moon point out these dramatic objects during that week, be aware that the summer full moon takes the lowest path through the sky, which is exactly the opposite of what the sun does in summer. Just imagine that the moon is the sun, and that would be the path that our sun takes through the sky during the winter solstice.
June 3. New moon is at 3:23 p.m. EDT. The moon is also at perigee, or closest to Earth today. That means we will have higher than usual tides today since normal spring tides happen twice a month, at new and full moon, but they get an additional foot or so higher if perigee happens to coincide with a full or new moon.
June 4. On this day in the year 2000, the Compton Gamma Ray Observatory was allowed to reenter our atmosphere in a controlled, fiery crash in the south Pacific about 4000 miles off the Australian coast. The larger pieces created massive sonic booms that were telecast live on CNN when it happened 8 years ago. In its 9 years of operation, this telescope gave us a wealth of information about the extremely violent, high energy aspects of our universe way beyond our own Milky Way Galaxy. It discovered about one new gamma ray burst each day. At first astronomers had no idea what could produce such powerful explosions, since they were about 100 times more powerful than a normal supernova. Then they coined a new term "hypernova" for this event. About one in 100,000 supernovae is a hypernova. That marks the final death cry of that massive star and the birth cry of a black hole, which is essentially a tear in the very fabric of the fourth dimensional space-time continuum.
June 10. First quarter moon is at 11:04 am.
June 18. Full moon is at 1:30 pm. This is also called the Strawberry or Rose Moon.
June 20. The Summer Solstice is at 7:59 pm.
June 26. Last quarter moon is at 8:10 am. Charles Messier was born on this day in 1730. He was a French astronomer and comet hunter who compiled a catalogue of 110 celestial objects which first appeared like they could have been comets, but they did not move from night to night. Those objects included star cluster, nebulae, and galaxies. About 70 of those objects are visible with just a good pair of binoculars.
June 30. At 7:14 am on this day in 1908, exactly 100 years ago over Tunguska, Siberia, a massive, 10 megaton explosion, occurred 5 miles above the earth. Caused by a comet or asteroid fragment that tore through our atmosphere at supersonic speeds, creating a shock wave that completely leveled 80 million trees over 1000 square miles, its impact was felt thousands of miles away. If it would have struck just four hours later, it would have completely destroyed the Russian Imperial city of St. Petersburg.
Bernie Reim
berniereim@masiello.com
Bernie Reim is an amateur astronomer 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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