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Hawaii Sky tonight, Bishop Museum http://www.astroday.net/BishopSky.html

Reprinted from here.

Skywatch Article
July 2008
By Carolyn Kaichi, Bishop Museum

PLANETS AND THE SUMMER MILKY WAY

The interesting thing about sky-watching is the fact that although the seasonal constellations are predictable, what you may see at any designated time is not. Planetary movement and other recurring events take place on different cycles than the background of stars so we can’t always count on seeing the same combination of sights in the sky at the same times. That keeps me in business.

So what we will see in the sky this July is not unusual, but a fortunate arrangement of celestial constituents that will be easy and convenient to view. Four naked-eye planets dot the evening skies this month, with two staging a nice pairing together and beautiful Venus making its reappearance back into the night. Although it might be challenging to spot Venus low in the western sky after sunset during the first half of the month, by the end of the July it will be climbing higher out of the light and easier to spot.

A nice highlight will be the conjunction of Mars and Saturn in the constellation Leo on July 9 and 10. The rust-colored planet and pale yellow Saturn have been slowly creeping closer over the past weeks and will be at their closest on those two dates (although the 10th is technically the closest date, both nights are good for viewing). Included in the lineup is the brightest star in Leo, Regulus, which is on that planet highway called the ecliptic. As a bonus, on July 5 a small crescent Moon joins the group as Mars closes in. That evening going from west to east, you can see the Moon next to the star Regulus, followed by Mars and Saturn. Make sure you start early however, because this gathering will set by 10:00 P.M.

Jupiter is also impressive in the east as the sun sets. The giant planet is at opposition now, meaning that it is on the opposite side of our sky than the sun (think “Sun, Earth, Jupiter” in that order). It appears bigger and brighter in the night sky at this time and is visible in the sky the whole night. Now would be a great time to take out a pair of binoculars and look for the famous features that characterize Jupiter, like the Galilean satellites and the distinct bands of color on the planet. The monster hurricane, the Great Red Spot, is visible with telescopes but not necessarily with average binoculars.

While the planets steal the spotlight this month, don’t forget to pay attention to the summer Milky Way! The hazy band of light extending from north to south is part of the galaxy we reside in and offers many binocular and telescopic sights along the way. The area roughly between Scorpius’ stinger and Sagittarius’ “spout” is particularly wide since that direction is the bulbous center of our galaxy, approximately 26,000 light years away. Rather than individual points of light we see the accumulation of the millions of stars obscured by gas and dust. Right now you can see the Milky Way stretching from the southwest in the direction of the Southern Cross (early in the evening) through the Summer Triangle toward Perseus in the northeast in the early morning hours.

EVENING PROGRAM UPDATE

With so many objects to look for in the skies, it’s difficult to cram everything into one article every month. Consider our planetarium as the next best thing to the real sky, one with a personal “guide” to the stars. An evening program is held on the first Fridays of the month, with sky viewing if the weather is clear. However since it falls on the 4th of July this month, the program has been moved to Friday, July 11. It begins promptly at 8:00 P.M. and reservations are strongly recommended. Call 848-4168.

PHOENIX UPDATE

The Phoenix lander is busily performing its tasks since touchdown on Mars a little over a month ago. What the mission has already done for space exploration was demonstrated by the difficult EDL phase, or Entry, Descent and Landing. Many previous missions were lost in this critical phase, including the predecessor of Phoenix, and since one of the science goals of the mission is to prepare for human exploration, NASA had to prove that landing a craft on Mars has improved dramatically. It appears that goal is well on its way. See http://phoenix.lpl.arizona.edu/ for more information.

The Planets

Earth:

The second of two annual opportunities to experience Lahaina Noon comes this month. Between May and July the sun passes directly overhead for areas within the Tropics. During Lahaina Noon objects that are directly perpendicular to the sun, such as flagpoles or fences, have no shadows since the “shadow” would be cast “under” the object. Times vary by location, so check the website for more information: http://www.bishopmuseum.org/planetarium

Also, aphelion takes place on July 3, the Earth’s farthest point in its orbit around the sun. Coincidentally the Moon is in a new phase at the same time, so the effect of the tides will be enhanced. Higher tides than normal usually occur during this alignment.

Mercury:

Mercury is in the morning sky now, rising around 4:30 A.M. in early July. By the last week it will be too close to the sunrise to spot as it rounds around the backside of the sun to reappear in the evening sky.

Venus:

For the casual viewer, Venus will be very difficult to spot until mid-month, when it is a little farther from the sun in the western sky at sunset. However the “window” to see it will be short for this month since the planet sets before darkness by 8:00 P.M.

Mars:

Mars is cruising through Leo, meeting up with Saturn along the way and by the end of the month will pass through the constellation on the way to Virgo. The planet is slowly receding from us in its orbit and dimming as it goes, but is still easily visible to the unaided eyes.

Jupiter:

Jupiter reaches opposition on the evening of July 9, rising in the east as the sun sets. If the weather is nice, this is an excellent night to see the four evening planets in the sky. You will need to get somewhere you can see all the way to the western horizon, and starting from that point shortly after sunset (around 7:30 P.M.) look for Venus low in the west, followed by Mars and Saturn close together about halfway up in the western sky and Jupiter rising in the east.

Saturn:
Although Mars and Saturn are set for a rendezvous Saturn’s position changes very little with respect to the starry background. The ringed planet is much farther away than our neighbor Mars, therefore orbiting the sun at a slower rate of speed. Where Mars orbits the sun in almost 687days, Saturn takes 29.5 years!

Questions? Contact Carolyn Kaichi @ hokupaa@bishopmuseum.org or 847-8203.

For more information on visiting Hawaii in general or touring the Big Island in particular, go to www.tourguidehawaii.com or here.

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(Reprinted from the Bishop Museum Website)

Skywatch Article

March 2008
By Carolyn Kaichi, Bishop Museum

SPRING SKIES

March brings in the spring season with the vernal equinox, the moment when the sun crosses the celestial equator on the way up to the northern hemisphere. This is also the beginning of “cross season”, or the time you can view the Southern Cross in the evening sky. The Southern Cross, also known as Crux, is the smallest of the 88 officially recognized constellations.

Here in Hawaii, this constellation is known as Hanaiakamalama, or “cared for by the Moon” and is part of the modern Polynesian navigational “star line” called Ka Iwikuamo’o, “The Backbone”. In Polynesian navigation this is one of the four reference lines of stars that runs from the north sky to the south. The Backbone starts with the North Star, Hokupa’a, through Ursa Major, Hokule’a (the star Arcturus), Hikianalia (Spica) in Virgo, Me’e (the constellation Corvus), finally to the Southern Cross.

You can start looking for the Southern Cross just before midnight looking out over the ocean on the Leeward side. There are four bright stars that make up the kite shape with a smaller fifth star between the second and third bright star (if you count the top star as number 1, then go clockwise). You can see the Southern Cross on the flags of many countries of the southern hemisphere, like Australia, Samoa and Papua New Guinea since this constellation is more prominent in the southern skies.

The Southern Cross was visible at least 5,000 years ago at higher latitudes in North America and Europe. According to one historian the Southern Cross was seen in Jerusalem at the time Christ was crucified. But because of precession, the “wobbling” of the Earth’s axis, the Cross is no longer visible at higher latitudes in the northern hemisphere.

Even here in Hawaii at 20 degrees north of the equator, the Southern Cross does not get very high above the horizon. Standing completely upright, the top star (Gacrux) is only a mere 12 degrees. In fact, the distance between the top and bottom stars of the upright Cross is the same distance as the bottom star (Acrux) to the horizon—another navigational feature. In the southern hemisphere, draw an imaginary line between the top and bottom stars and they will point the way to the South Celestial Pole. In the northern hemisphere, the North Star conveniently marks the North Celestial Pole but there is no equivalent star in the south.

Because the Southern Cross is so low in the sky and close to the South Celestial Pole, its path in the sky is short. From the time it rises to the time it begins to set it is only in the sky for around six hours, whereas objects that rise closer to due east and set due west takes approximately 12 hours to traverse the sky. In other words, don’t expect to see the Southern Cross in the sky all evening long!

Earlier in the evening you will still see the signature stars and constellations of the winter—Orion, Taurus, Gemini and Auriga are some of the more famous. Orion’s dog, Canis Major (translated as “Big Dog”, not too original but descriptive) has the distinction of having the brightest star as seen from the Earth. Sirius’ status as the brightest star has more to do with its closer proximity rather than its properties—there are many larger and luminous stars in our skies but they are just farther away. Low in the south under Sirius is Canopus in Carina, the second-brightest star in our sky.

Looking to the east of Canopus, you can see another cross-like shape—surprise, you found the “False Cross”! The False Cross is actually made up of stars from two separate constellations that are low in the southern skies. The stars of Vela the sails, and Carina the keel, comprise the False Cross. Those two constellations along with Pyxis the compass and Puppis the stern make up pieces of the ship Argo that carried Jason and the Argonauts on great adventures in Greek mythology.

The “real” Cross will be visible in the sky until around July, when it will then begin to set by the time darkness falls. To find the real Southern Cross, remember that Orion and pals are low in the west by the time the Cross starts to rise and look for the two “pointer stars” to the east of the constellation that point to the top star of the Cross. These stars are Alpha and Beta Centauri in the constellation Centaurus.

The Planets

Earth:

The Vernal Equinox falls on March 19 here in Hawaii, 7:49 P.M. HST. This is the earliest spring date since 1896. Also, Daylight Savings Time begins Sunday, March 9. ADD an hour to most times on the mainland.

Mercury:

Mercury and Venus spend the month huddled in the eastern morning sky just before the sunrise. On March 5 a very thin crescent Moon will join the pair. Neptune and eventually Uranus are also in the vicinity (Uranus comes close to Venus in the last half of the month), and Jupiter is also high in the sky at the time. You will need a telescope to view Neptune and Uranus.

Venus:

Venus rises around 5:30 A.M. at the beginning of March, close to neighbor Mercury. By the end of the month it is getting very close to the sunrise and more difficult to see, rising only around 45 minutes before the sun. Venus is making its way back to the evening sky and will pass in back of the sun (superior conjunction) in June.

Mars:

As we get closer to the summer months the sky darkens later, so although Mars is high in the sky by 7:00 P.M. it will be hard to spot right away. We are already leaving Mars behind after passing by in December last year, and as the Red Planet recedes it looks smaller and dimmer in our night sky. Throughout March Mars sits above the horns of Taurus next to the legs of the brother Castor in Gemini.

Jupiter:

Jupiter rises by 3:45 A.M. in early March right off the handle of the Sagittarius “teapot” asterism. Until Venus rises two hours later, Jupiter commands the sky as the brightest object aside from the Moon.

Saturn:
Saturn was in opposition last month and is already in the eastern sky at dusk. The planet is in Leo the Lion and sits to the east of the lion’s heart, the star called Regulus, which Saturn easily outshines. On March 18 the almost-full Moon (three days short) passes right next to the pair.

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