When you want to see the stars, find someplace dark
Today Mercury will be at superior conjunction. After today the planet will reappear in the evening sky, rising high enough from the Sun’s glow to be seen early next month.
As Mercury is on an orbit inside that of Earth’s it will see both inferior and superior conjunctions as it passes from the evening sky to the dawn sky and back again.
Summer solstice occurs today at 18:24HST. Today the Sun will occupy the most northerly position in the sky of the year. The term solstice comes from the latin terms Sol (the Sun) and sistere (to stand still). On this day the Sun seems to stand still as it stops moving northwards each day and begins move to the south. This is the first day of summer as marked by many cultures in the northern hemisphere. Alternately this is the first day of winter for those living south of the equator.
This year many calendars will mark September 21st as the summer solstice, and so it is for much of the world. Here in Hawaiʻi the solstice actually occurs on the 20th when considering the time zone differences.
| 2017 Solstices and Equinoxes | ||||
|---|---|---|---|---|
| UT | HST | |||
| Perihelion | Jan 4 | 14:18UT | Jan 4 | 04:18HST |
| Vernal Equinox | Mar 20 | 10:29UT | Mar 20 | 00:29HST |
| Summer Solstice | Jun 21 | 04:24UT | Jun 20 | 18:24HST |
| Apehelion | Jul 3 | 20:11UT | Jul 3 | 10:11HST |
| Autumnal Equinox | Sep 22 | 20:02UT | Sep 22 | 10:02HST |
| Winter Solstice | Dec 21 | 16:28UT | Dec 21 | 06:28HST |
| Source: USNO data Services | ||||
Tomorrow morning, June 20th, a pretty crescent Moon will be located close to a brilliant Venus. The Moon will be a slim 18% crescent a little under 6° from Venus shining at -4.2 magnitude. The pair will rise about three hours before sunrise at about 2am, look for the two above the brightening glow of dawn.
W. M. Keck Observatory press release…
Astronomers have shown what separates real stars from the wannabes. Not in Hollywood, but out in the universe.
“When we look up and see the stars shining at night, we are seeing only part of the story,” said Trent Dupuy of the University of Texas at Austin and a graduate of the Institute for Astronomy at the University of Hawaii at Manoa. “Not everything that could be a star ‘makes it,’ and figuring out why this process sometimes fails is just as important as understanding when it succeeds.”
Dupuy is the lead author of the study and is presenting his research today in a news conference at the semi-annual meeting of the American Astronomical Society in Austin.
He and co-author Michael Liu of the University of Hawaii have found that an object must weigh at least 70 times the mass of Jupiter in order to start hydrogen fusion and achieve star-status. If it weighs less, the star does not ignite and becomes a brown dwarf instead.
How did they reach that conclusion? The two studied 31 faint brown dwarf binaries (pairs of these objects that orbit each other) using W. M. Keck Observatory’s laser guide star adaptive optics system (LGS AO) to collect ultra-sharp images of them, and track their orbital motions using high-precision observations.
“We have been working on this since Keck Observatory’s LGS AO first revolutionized ground-based astronomy a decade ago,” said Dupuy. “Keck is the only observatory that has been doing this consistently for over 10 years. That long-running, high-quality data from the laser system is at the core of this project.”
Continue reading “Astronomers Prove What Separates True Stars from Wannabes”
How do you organize your photos? The answer to that is critical. Anyone who generates a lot of images, and that is just about everyone these days needs to answer that question.
The trick is to develop a process and to use it… Religiously. I can not tell you how to do it, I can just tell you how I do it and offer a few suggestions.
There are two basic approaches, simply come up with a way to organize the images into a directory using nothing more than your operating system. The other approach is to use some form of photo organizing software to aid in the task. I do make a large assumption here, that the images are in digital format, not negatives and slides. For that you will have to look elsewhere for answers.
Today the planet Saturn will pass through opposition, directly opposite the Sun in our sky.
During opposition the planet and rings will be slightly brighter than normal, an effect known as the opposition effect. The effect is most notable in the rings where the apparent brightness can increase by 30%. The effect is a combination of two factors, shadow hiding and the retro-reflective properties of the ring particles.
