Starry Heavens Newsletter
September 2017
“Grand Finale” for the Cassini-Huygens space probe
September 15, 2017 will be the end of an era and the historic “Grand Finale” for the Cassini-Huygens space probe.
Cassini–Huygens is an
unmanned spacecraft sent to the planet
Saturn. While
Cassini is the fourth
space probe to visit Saturn, it is the first to enter Saturn’s orbit. It has studied the planet and its many
natural satellites since arriving there in 2004.
Cassini has far exceeded its lifespan. Since this spacecraft has proven so active and prolific, scientists decided in 2010 to push back its Grand Finale to 2017, thereby using up every kilogram of propellant to explore Saturn. Cassini will end up with an empty gas tank and will crash into Saturn.
http://saturn.jpl.nasa.gov
The $3.2 billion Cassini-Huygens mission has made a number of mind-blowing discoveries during its time in the Saturn system. For example, Cassini spotted liquid-hydrocarbon seas on
Titan, making the moon the only place beyond Earth known to harbor bodies of stable liquid on its surface. The mission's piggyback lander, called Huygens, touched down on Titan in January 2005, becoming the first probe ever to land on a body in the outer solar system. Cassini also discovered
Enceladus' amazing water plumes, which in turn helped reveal that the satellite hosts an ocean of liquid water beneath its icy shell. The probe has imaged Saturn's diverse family of moons at a level of detail that was not possible before.
The Cassini-Huygens mission has been a decades-long collaborative odyssey of NASA, the European Space Agency and the Italian Space Agency. The probe's 3-minute final dive into Saturn's atmosphere on Sept.15, will be a bittersweet moment for the community of scientists from around the world who have been involved for so long - some scientists have spent much of their career following the Cassini-Huygens mission.
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But back on Earth it is business as usual - As in the Autumnal Equinox
The Autumnal equinox—also called the September equinox—is the astronomical start of fall in the Northern Hemisphere and spring in the Southern Hemisphere.
The word equinox is derived from two Latin words: aequus (equal) and nox (night) thus, “equal night” when night and day are about the same length of time. During the equinox, the Sun crosses what we call the “celestial equator” (just imagine the line that marks the equator on Earth extending up into the sky) from north to south. The moment of the equinox is defined as the point at which the center of the Sun’s disk crosses this imaginary line. At this point, the amount of nighttime and daytime are
roughly equal to each other.
How does this work, you ask? Viewed from Earth, it looks like the Sun travels around us, tracing a path in the sky called the
ecliptic. In reality, this path is the orbital plane of the earth. Since the Earth's axis is tilted 23.5 degrees to this plane, its equator intersects the ecliptic at two points called the
equinoctial points, once in Spring (Vernal Equinox) and once in Autumn (Autumnal Equinox).
On these two days, the Sun crosses the celestial equator and will rise due east and set due west. All the other days of the year the Sun rises north or south of east and sets north or south of west. Also, the length of day and night are nearly equal but not absolutely equal because the sun’s light is bent or refracted in the Earth’s atmosphere so we see light from the Sun before the center of the Sun has crossed the horizon. This is important because the instant of the equinox is measured according to when the center of the Sun crosses the horizon. Because we see light from the Sun at Sunrise before its center has crossed the horizon and because we continue to see light from the Sun after the center of the Sun has set below the horizon, night and day are not precisely equal. How much night and day are off from equal depends on where one is on Earth. The two days of the year when the length of day and night are exactly equal-called the Equilux-generally occur a few days before the spring equinox and a few days after the autumn equinox.
In Hawaii the Autumnal Equinox will occur Friday, September 22, 10:02am HST. However, the day of nearly equal light (
Equilux) will occur five days later on September 27, when sunrise occurs at 6:22am HST and sunset at 6:22pm HST. On this day of the
equilux daylight is estimated to be 12 hours and 6 seconds and night 11 hours and 54 seconds.
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Reservations Suggested
Due to limited seating of 84 attendees in the Imaginarium, we recommend making reservations for our programs. Call (808) 235-7433 between 8:30am - 3:30pm, Monday - Friday. Reservation phone line is not available on weekends or holidays.
Our new admission prices beginning August 2017 are:
- $8 General admission
- $7 WCC students, military, seniors (65 years or older), with ID
- $6 Children (ages 4-12 years)
- Free for children under 4 years of age (1 per paying adult), and WCC faculty or staff with university ID
CASH & CHECK ONLY. An ATM is located on campus behind the Imaginarium building, next to The Hub coffee shop.
Please pick up and pay for reserved tickets at the Imaginarium Box Office at least 15 minutes prior to showtime. Unclaimed tickets may be sold to waiting customers on a first come, first served basis.
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As always, we welcome your feedback or questions, feel free to phone (808) 235-7350 or email to dineene@hawaii.edu. If you would like information regarding our
Adopt-a-Show sponsorship program please
click here.
Dineene O'Connor
Manager, Hōkūlani Imaginarium
Windward Community College
Hale Imiloa 135A
Office (808) 235-7350
