THE SOUTHWORTH PLANETARIUM
70 Falmouth Street Portland, Maine 04103
(207) 780-4249 usm.maine.edu/planet
43.6667° N 70.2667° W
Altitude: 10 feet below sea level
Founded January 1970
2021-2022: CXXXIV
"Everytime I see an adult on a bicycle, I no longer despair for the future of the human race." H.G. Wells
THE DAILY ASTRONOMER
Wednesday, June 8, 2022
June 2022 Night Sky Calendar Part III
TUESDAY, JUNE 21, 2022: SUMMER SOLSTICE (GOLD EVENT!!!)
At 5:13 a.m., June 21, 2022, astronomical summer will begin in the northern hemisphere while astronomical winter starts in the southern hemisphere. Consequently, we should refer to this event as the June Solstice.
We have seasons because Earth is tilted relative to the plane of its orbit. This tilt, called the "obliquity," measures about 23.5 degrees. As Earth revolves around the Sun, the pole orientation relative to the Sun continually changes.
Earth's tilted orbit. As Earth revolves around the Sun, the pole orientation constantly changes. On the summer (June) solstice, the north pole is aligned as close to the Sun as possible. On the winter (December) solstice, the south pole is pointed as close to the Sun as possible. Summer begins in the northern hemisphere on the June solstice. Image: Earthsky.org
Throughout the year, a northern hemisphere observer will notice the Sun's altitude changing from season to season. On the vernal (March) and autumnal (September) equinox, the Sun rises due east and sets due west. In the spring and summer, the Sun rises north of east and sets north of west. On the summer solstice, the Sun rises as far north of east and sets as far north of west as possible. In the autumn and winter, the Sun rises south of east and sets south of west. On the winter solstice, the Sun rises as far south and sets as far south as possible.
The Sun's changing altitude throughout the year. As Earth's pole alignment changes throughout the year, the Sun's altitude varies: from a minimum position on the winter (December) solstice to a maximum altitude on the summer (June) solstice. The Sun's altitude oscillates between these two extremes during the year. The winter solstice is also known as "Midwinter," and the summer solstice as "Midsummer." Image: Earthsky.org
The Sun's altitude directly relates to its time above our horizon. The higher the altitude, the greater the path between horizons. As Earth's speed is constant along any line of latitude -fastest at the equator and progressively slower with increasing distance from the equator- the Sun will remain above the horizon for a longer period of time in the summer than the winter.
Summer is warmer than winter because the Sun's angle is higher and it heats the ground more efficiently. The rising heat from the surface warms the air above it.
How high does the Sun ascend on the summer solstice? That all depends on the latitude. For instance, Portland, ME's latitude is approximately 43.5 degrees. The celestial equator, or the projection of Earth's equator onto the celestial sphere, extends from due east to due west and passes 46.5 degrees above due south. (To calculate this angle for any latitude, subtract the latitude from 90 degrees.*) On the summer solstice, the Sun is located 23. 5 degrees north of the celestial equator. So, when the Sun crosses the meridian on the summer solstice, it will be 46.5 + 23.5 = 70 degrees above due south: its highest possible altitude at this location.
Regard the Tropic of Cancer as another example. It is aligned with the 23.5 N parallel. At this location, the celestial equator extends 66.5 degrees above due south. On the summer solstice, the Sun will pass 66.5 + 23.5 = 90 degrees above due south, or at the zenith. The Tropic of Cancer marks the northernmost point at which the Sun can ever occupy the zenith. The Tropic of Capricorn (23.5 degrees South) defines the southernmost boundary of the zenith Sun. As one might assume, the Sun occupies the zenith at the Tropic of Capricorn on the winter (December) solstice.
Even though the Sun's altitude will now start decreasing, our weather will continue to become warmer over the next couple of months. Here, the average high temperature reaches its maximum around August 1, the cross-quarter day between the summer solstice and autumnal equinox.
TUESDAY, JUNE 21: MOON NEAR JUPITER (BRONZE EVENT!)
See the waning crescent moon (45% illuminated) close to Jupiter, the second brightest planet. Both worlds will rise by 1:10 a.m. and will remain visible for the rest of the night.
Jupiter will appear as a bright dot to the north of the moon. Find both bodies within the constellation Pisces the Fish.
WEDNESDAY, JUNE 22: MOON NEAR MARS
Tonight, the waning crescent moon (35% illuminated) passes south of Mars. At magnitude 0.6, Mars is currently almost as bright as Betelgeuse, which isn't currently visible. However, it is still about twelve times dimmer than Jupiter. One should have no problem finding Mars tonight. Both the moon and Mars will rise by 1:40 a.m.
Tonight, the waning crescent moon (35% illuminated) passes south of Mars. At magnitude 0.6, Mars is currently almost as bright as Betelgeuse, which isn't currently visible. However, it is still about twelve times dimmer than Jupiter. One should have no problem finding Mars tonight. Both the moon and Mars will rise by 1:40 a.m.
An interesting note: the moon will actually occult -move in front of- Mars for observers in the extreme southern part of the world. The visibility region is designated on the map below.
While we won't see this occultation, we will see the lunar occultation of Mars on December 8, 2022!
More on that event when the time comes.
THURSDAY, JUNE 23: MERCURY 2.9 DEGREES NNW OF ALDEBARAN
Oh, now just wait a minute! Summer started two days ago and now we can see Aldebaran, the brightest star in Taurus the Bull?! As a reminder, Taurus is the westernmost of the "winter star patterns." Well, yes, Taurus the Bull has returned to the eastern pre-dawn sky. (Remember that Orion, itself, returns in early August.) Early this morning one will observe Mercury close to Aldebaran. At magnitude 0.0, Mercury will be slightly more than twice as bright as Aldebaran. Aldebaran and Mercury will rise by 4:00 a.m.
SUNDAY, JUNE 26: MOON NEAR VENUS
Find the thin waning crescent moon (6% illuminated) close to Venus low in the pre-dawn eastern sky. Ordinarily, we confer one of the medals onto the Moon/Venus appulse. However, this gathering is low along the eastern horizon and somewhat difficult to observe.
MONDAY, JUNE 27: MOON NEAR MERCURY
This appulse will prove to be even more elusive than yesterday's event. See the waning crescent moon (2% illuminated) close to Mercury. They'll both be above the eastern horizon by 3:45 a.m.
TUESDAY, JUNE 28: NEW MOON
Beginning of lunation cycle 1231
PLANET WATCH
MERCURY:
Observers will find Mercury in the pre-dawn eastern sky throughout the month. The best time to search for it is mid-month, around the time when it reaches greatest western elongation. VERDICT: Find Mercury during the second or third week of June. It will be more difficult to find toward the beginning and end of June.
VENUS:
Yes, all the planet action occurs in the morning sky. Find Venus low in the eastern sky throughout the month. VERDICT: By virtue of its brightness, Venus is easy to find provided one ventures out an hour before sunrise.
MARS:
Mars is drawing closer to Earth and becoming brighter. By month's end it will be as bright as Betelgeuse! Mars rises by 2:00 a.m. at month's beginning and by 1:15 a.m. at month's end. VERDICT: Mars is much easier to see now that it was earlier this year. If you're an early riser, seek out the red planet. Otherwise, you can wait until later this summer or autumn, when Mars rises earlier and appears much brighter.
JUPITER: (PICK PLANET!)
Jupiter is now brighter than any night sky star! It rises just before 2 a.m. at month's beginning, but will be up a half an hour before midnight at month's end. VERDICT: This is a perfect time for late night or early morning observers to find Jupiter, which now appears as a bright beacon in the eastern post-midnight sky.
SATURN:
Although it is the dimmest of the morning planets, Saturn rises first. Saturn appears around 12:45 a.m. at month's beginning and rises at 10:45 p.m. by month's end. VERDICT: Saturn doesn't dazzle, but is still easy to find if you're out in the late evening or early morning.
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