Hurricanes whirling past, satellites breaking up overhead. I am reluctant to ask… What is next?
One of the more sublime sights seen from Mauna Kea is the shadow of the mountain rising through the mist and haze at sunset. One of the more sublime sights in the heavens is the Earth’s shadow crossing the face of the Moon, a total lunar eclipse. It is possible to combine these two phenomena if the timing is right, the Earth’s shadow seen twice.The moment of totality in a lunar eclipse occurs when the full Moon is directly opposite the Sun in the sky. By simple geometry this same anti-solar point is where the tip of the mountain’s shadow will be projected for an observer standing near the summit of the same mountain. If the eclipse is in progress at sunset, and you are standing on the summit of a suitably prominent mountain, you will see the Earth’s shadow both in the sky and obscuring the Moon.
Back on Feb 20th, 2008 the timing was right. A friend of mine, Alex Mukensnable, noted the timing and set up to catch the eclipsed Moon rising in the shadow. The result was a great set of photos. The photo is nice enough as a still, be he did more than that, he shot the event as a timelapse and assembled a video of the rising Moon.
There are several possible variations depending on the timing with this sort of event… If the Moon was at the height of totality rising it would also be right at the tip of the mountain shadow as it rises. This is a relatively rare event as the timing requirements are tight. Unfortunately it would also be quite dim, darkened by the shadow, and not easily seen as it rose.
As lunar eclipses are long events, taking several hours to complete, the likelihood of the Moon being in at least the partial eclipse phase at sunset is fairly good. Still a rare event, but not extraordinarily so. Thus for a single site, the summit of Mauna Kea this even happens in both 2008 and 2015.
As the Earth’s shadow is about 2.6° across at lunar orbit, the closest a partially eclipsed Moon will be seen from the the very tip of the shadow is about 1.3°. This is a bit less than three lunar diameters. Of course these numbers will vary a few percent depending in the distance to the Moon which changes as it makes its elliptical orbit.
The Moon moves slowly across the sky from west to east, thus before totality the Moon would be above the tip of the mountain shadow. After totality, with the eclipse ending, the eclipsed Moon will be in the shadow. Placing the Moon in the shadow also makes it easier to see, the bright crescent a better contrast to the dark shadow. This is the case for the 2008 eclipse captured by Alex.
Of course you could reverse all this timing and watch the event at moonset and sunrise. If the eclipse was just starting at dawn it would again place the eclipse in the mountain shadow.
Another important point to remember is that the shape of the mountain’s shadow has little to do with the shape of the mountain. The shadow will always be a neatly conical form due to the effects of projection.
What brings this event back to the fore is that the timing will soon be correct to see this same event again. The total lunar eclipse of Sept 27th, 2015 will be a bit of a dud for Hawaii, most of the eclipse already over as the Sun sets and the Moon rises over the islands. However, this event will feature very similar timing to the 2008 eclipse. The Moon will still be in partial eclipse when it rises. As it rises a short time after full Moon it will again be deep in the shadow of Mauna Kea as it comes over the horizon.
You know where you will find me on the evening of the 27th. Now I just need some clear weather that day.
So last night a Russian satellite burns up over Waikoloa… And I miss it!!
Some of my friends and co-workers did not, asking me what it was this morning after personally witnessing it. There are videos all over Facebook. I am so envious!
The satellite was Cosmos 1315, a Russian signals intelligence mission launched in 1981. It re-entered just west of the Big Island about 11pm HST last night.
I have embedded a video below, the language is more than a bit rough, a few f-bombs. The language goes to illustrate just how dramatic the event was. Aside from the unfortunate choice of vertical format, the video is surprisingly good.
Several items stand out in the video… The giveaway that it is man made is the very slow speed of the object, not the high speed typical of most meteors. You can also see the satellite coming apart, fragments breaking away. Larger meteors can also do this, breaking up upon re-entry.
The guy (I believe Chris Jardine) identifies the object as a meteor, a good guess. I first thought meteor when I saw the video. I received word a bit later from Steve Cullen who passed along a link to information on the satellite. The gal thinks comet? We need to do more public outreach and education around the island!
A beautiful image from the NOAA-NASA GOES Project of a full disk Earth. Off to the west of the islands you can see the re-formed Hurricane Kilo, to our immediate east if Ignacio, with Jimena right behind. The forecast calls for tropical storm force winds to begin on the island as soon as tonight. Also visible is an active region of thunderstorms off the Mexican coast, the spawning ground for the next hurricane.
Click on the image for full glory!
Almost the entire Keck Observatory staff forming the hexagonal outline of one of the primary mirrors. Seeing the size of one of the mirrors like this really puts things in scale.
Our director, Dr. Hilton Lewis, is center front. Do not look for me… I am standing on the ladder taking the photo.
The intensifying El Niño event in the Pacific is looking to be the strongest event of the last 50 years. Some news outlets have dubbed it the “Godzilla” El Niño.
Officially referred to as ENSO, or El Niño Southern Ocsillation, this event is a period of dramatically warm surface water temperatures that occurs across the equatorial Pacific Ocean. These events usually alternate with periods of cooler temperatures, or La Niña events, and can have dramatic effects on weather across the globe.
The immediate effects of the warming water are already being felt… Water temperatures around the islands are at least 2°C above normal, pushing our normally cool water into near bathtub temperatures. Local divers are commenting on the warm water temperatures, those who normally wear wet suits are comfortable without.
This warm water is also fueling the series of hurricanes sweeping past the islands. The storms just keep coming. It will be an interesting year!
It looks like yet another hurricane is coming this way, the island squarely in the predicted path. The seemingly endless series of storms passing through is making the 2015 hurricane season one of the most active on record.
Ignacio is expected to become a major storm, crossing the island as a full hurricane. If that is not enough we have Jimena further out and following a similar track. No one expects that to be the end of the series either, with sea water temperatures well above normal and continuing to warm there will be further storms.
I am truly grateful we live on the leeward side of the island, sheltered from the worst of the effects of these storms. A 14,000ft mountain standing between our house and the oncoming hurricane. I do worry about our many friends who live on the other side of the island.
As the storm nears and if it becomes apparent that the island will be hit we will perform our last minute storm preparations, fill the water jugs and secure the lanai furniture. Everything else is already done, held over from the last storm, plenty of emergency supplies and propane on-hand.