Category: Astronomy

Exploring the cosmos

All Five Planets Visible

For much of the month all five naked eye planets will be visible at sunset. Mercury, Venus, Mars, Saturn, and Jupiter can all be seen easily if one knows where to look. Indeed, four of the five are quite bright and quite hard to miss. Neptune and Uranus are generally too faint to be seen without optical aid.

Conjunction
Venus and Jupiter over the Keck 1 dome
Tonight, August 1st, Venus is just rising high enough to be easily seen. It will be a mere 5° above the horizon at 19:30, probably bright enough to be seen against the glow. You can find Mercury a little higher, about 10° above the horizon. Jupiter is obvious well above the sunset as a bright object shining at -1.7 magnitude. Mars and Saturn are visible to the south on the top of Scorpio.

There will be a nice conjunction of the Moon and Jupiter, only 46′ apart, on the 5th of August. Mercury reaches eastern elongation on the 16th of the month. A beautiful triplet of Mercury, Venus, and Jupiter will gather in the days around the 22nd. Keep an eye to the sky for the month to be treated to some nice planetary views.

More Than 100 Planets Confirmed in Single Trove

W. M. Keck Observatory press release…

An international team of astronomers have discovered and confirmed a treasure trove of new worlds. The researchers achieved this extraordinary discovery of exoplanets by combining NASA’s K2 mission data with follow-up observations by Earth-based telescopes including the W. M. Keck Observatory on Maunakea, the twin Gemini telescopes on Maunakea and in Chile, the Automated Planet Finder of the University of California Observatories and the Large Binocular Telescope operated by the University of Arizona. The team confirmed more than 100 planets, including the first planetary system comprising four planets potentially similar to Earth. The discoveries are published online in The Astrophysical Journal Supplement Series.

Image montage showing the Maunakea Observatories, Kepler Space Telescope, and night sky with K2 Fields and discovered planetary systems (dots) overlaid. Credit: Karen Teramura/IFA , Miloslav Druckmüller, NASA
Image montage showing the Maunakea Observatories, Kepler Space Telescope, and night sky with K2 Fields and discovered planetary systems (dots) overlaid. Credit: Karen Teramura/IFA , Miloslav Druckmüller, NASA
Ironically, the bounty was made possible when the Kepler space telescope’s pointing system broke.

In its initial mission, Kepler surveyed a specific patch of sky in the northern hemisphere, measuring the frequency with which planets whose sizes and temperatures are similar to Earth occur around stars like our sun. But when it lost its ability to precisely stare at its original target area in 2013, engineers created a second life for the telescope that is proving remarkably fruitful.

Continue reading “More Than 100 Planets Confirmed in Single Trove”

Andrea Ghez at WHAC

Not a call I want to get just a few hours before our astronomy club meeting… My presenter for the evening? Tooth extraction?

Andrea Ghez at WHAC
Andrea Ghez talking at the July WHAC meeting
Yeah, we have no main lecture for the evening.

The West Hawaii Astronomy Club is not a large club, more than a dozen folks is a big meeting. Still, these are dedicated amateur astronomers that can be relied upon to help out with school star parties and observatory events. They have driven all the way to Waimea because I promised them a lecture from an astronomer. A few folks come from Kona 45 minutes to an hour away. I really want to give them something worth the effort of getting here.

They will just have to settle for a talk with Andrea Ghez.

Yes, that Andrea, the closest thing we have to a superstar in astronomy. Discoverer of the black hole at the center of our galaxy, winner of the Crafoord Prize and the Bakerian Medal… That Andrea.

I ran into Andrea at dinner next door to the observatory, we know each other from other outreach events and swapping photos. She is a regular Keck observer with research that concentrates on the massive black hole at the core of our Milky Way galaxy. I asked her if she could come talk with the club, or rather I begged a bit. Being the gracious lady she is, she said yes. Thanks Andrea!!

It was so much better than the warmed over presentation I had thought I would be giving this evening. The small group allowed something closer to a conversation than a lecture. There were some good questions too! We moved past the basics pretty quickly with a group that knew more than a little about the subject. I found the evening very informative, I think everyone did.

Mercury and Venus

The two inner planets will rendezvous in the sunset over the next few days. Venus appeared in the sky a few days ago having just emerged from superior conjunction. Mercury will emerge quickly from the solar glare to pass Venus only 10° from the Sun. This conjunction will be quite low and a bit in the bright glow of sunset, perhaps somewhat challenging to spot.

This evening the two will be about 2° apart, and will quickly converge. On July 16th the two will be only 32′ apart, about the diameter of a full Moon. After that the two will quickly separate. Interestingly on the 17th the pair will pass through the M44 star cluster, though perhaps it will still be a bit bright to appreciate this dimmer cluster.

Late in the month this trio of bright planets will continue their dance in a set of conjunctions that lasts into September. The highlight will be on August 27 when Jupiter and Venus will pass within 12′ of each other while Mercury is only 5° away.

Moon and Mercury
The Moon appears as a thin crescent beside the planet Mercury, photo taken from the summit of Mauna Kea on 12Oct2007

Apehelion

Today the Earth is furthest from the Sun, a point called apehelion. We will be about 152,096,000km (94,508,000miles) from the Sun. Compare this to the 147,099,000km (91,403,000miles) we were at perihelion on January 2rd, a difference of about 4,996,000km (3,104,000miles) occurring throughout one orbit.

It may seem odd that we are actually at the furthest for the middle of northern summer, you just have to remember that proximity to the Sun is not the cause of the seasons. The seasons are caused by the axial tilt of the Earth, creating short and long days throughout the year, with a resulting change in the angle and intensity of the sunlight.

2016 Solstices and Equinoxes
  UT HST
Perihelion Jan 2 22:49UT Jan 2 12:49HST
Vernal Equinox Mar 20 04:30UT Mar 19 18:30HST
Summer Solstice Jun 20 22:34UT Jun 20 12:34HST
Apehelion Jul 4 16:24UT Jul 4 06:24HST
Autumnal Equinox Sep 22 14:21UT Sep 22 04:21HST
Winter Solstice Dec 21 10:44UT Dec 21 00:44HST
 
Source: USNO data Services