Feb 01

What’s Up in the Sky

What’s Up in the Sky – February, 2017

There’s Much to See When the Sky Clears

February usually does not lend itself to stargazing for several reasons – bad weather, cold nights, and bad weather. It is unfortunate because on clear nights there is quite a bit to see.

You probably have noticed the bright object in the southwest after sunset, and I’m sure regular readers know that it is the planet Venus. And if it is clear tonight you may spot a lovely crescent Moon just to its left. Both objects provide some good viewing during the first half of the month.

On February 3rd Venus reaches its highest point in the sky at sunset, and it will be at its brightest on the 16th. In fact, Venus is so bright it could be visible in the daytime in a very clear sky. Try looking due south about halfway between the horizon and the zenith (directly overhead) around 3:30 p.m. Stand in the shadow of a tree or building and use binoculars at first to locate it, then make a naked eye attempt. It’s a long shot, but I’m sure it would be something you’ve never seen before. It will continue to dominate the southwest sky in the early evening throughout the month.

A more challenging object to observe is the planet Mars, located about five degrees (the width of three fingers held at arm’s length) to the upper left of Venus. You will need binoculars to see it, however, but the Moon might help you find it tonight as it will form a small isosceles triangle the the two planets, with Mars at the top of the triangle. Look around 7:00 p.m. when they are still relatively high above the horizon.

February is also one of the best times of the year, weather notwithstanding, for constellations as well. With two dogs to his left, a rabbit at his feet, and a bull to his right Orion dominates the southern sky for most of the month and is always a favorite for young and old alike. Follow the line formed by the three belt stars down and to the left to Sirius, in the constellation Canis Major and the top two stars left to Procyon in Canis Minor. These are Orion’s two hunting dogs. Hiding safely under his feet is Lupus, the Rabbit, but it is very dim and difficult to see.

Returning to Orion, follow a line from Rigel, lower right, to Betelgeuse, upper left, (his two brightest stars) to the Gemini twins, Castor and Pollux, then continue clockwise to Auriga, the Charioteer, with the bright star Capella and Taurus, the Bull, where you can spot the Pleiades cluster farther west. Also look for the V-shaped cluster of stars, the brightest of which is Aldebaran, the “Eye of the Bull”. Six of these bright stars, Rigel Aldebaran, Capella, Pollux, Procyon and Sirius form the “Winter Hexagon”, a lovely winter sight up in the sky.

This month in history:

Feb. 1: Shuttle Columbia breaks apart during reentry killing all 7 astronauts – 2003
Feb. 6: Alan Shepard hits first golf balls on the Moon – 1971
Feb. 15: Galileo Galilei born – 1564
Feb. 18: Pluto discovered – 1930
Feb. 20: John Glenn is first American to orbit Earth – 1962
Feb. 23: Light from supernova 1987a reaches Earth – 1987

Jan 03

What’s Up in the Sky

What’s Up in the Sky – January, 2017

2016 – An Historic Year for Astronomy

This is a time of year traditionally known for reflection and anticipation and last year was also been a year of milestones for astronomers. It seems appropriate to look back on major events and discoveries that will make 2016 historic.

Thought by many to be the greatest discovery of the year, as well as one of the greatest in history, was the detection of gravitational waves, ripples in the fabric of spacetime and the result of a cataclysmic event in the distant universe. Although the gravitational waves were detected in September of 2015, it took until February of this year for scientists to verify the observation after much painstaking analysis of the data.

The gravitational waves were a result of a merger of two black holes to produce a single, more massive, black hole, 1.3 billion years ago. The observation confirmed a major prediction of Albert Einstein’s 1915 general theory of relativity and gives astronomers a completely new method by which to study the universe. The discovery was made using the LIGO (Laser Interferometer Gravitational-wave Observatory) detectors, located in Hanford WA and Livingston, LA.

On July 4th, the Juno spacecraft entered into orbit around the giant planet, Jupiter. Although not the first spacecraft to study Jupiter (there have been eight others) nor even the first to orbit the planet (that was Galileo in 1995), Juno is unique in that its orbit is polar rather than equatorial and brings it far closer to the giant planet’s cloud tops than any other spacecraft. With its mission still in its early stages, we can look forward to many great discoveries when Juno probes Jupiter’s deep structure, studies its atmospheric circulation and attempts to learn more about the high-energy physics of its magnetic field.

In September, the European Space Agency’s Rosetta spacecraft ended its mission with a soft landing on the surface of Comet 67P. After two years of study that included ground-breaking observations at extremely close distances, Rosetta has provided scientists with a wealth of data that should keep them busy for years.

The New Horizons spacecraft was still in the news as it finished returning all the data from its flyby of Pluto. One major discovery was that of a massive ice sheet whose top lies 2.5 kilometers below Pluto’s mean elevation. Most likely an impact basin, it may have been formed by a glancing impact of a 200-kilometer body.

And the new year promises to be an exciting one here in the U.S. with next August’s “Great American Solar Eclipse”, an event you will NOT want to miss. It will be the greatest thing you have ever witnessed up in the sky.

Dec 13

Big Science in Small Packages

By Marcus Woo

About 250 miles overhead, a satellite the size of a loaf of bread flies in orbit. It’s one of hundreds of so-called CubeSats—spacecraft that come in relatively inexpensive and compact packages—that have launched over the years. So far, most CubeSats have been commercial satellites, student projects, or technology demonstrations. But this one, dubbed MinXSS (“minks”) is NASA’s first CubeSat with a bona fide science mission.

Launched in December 2015, MinXSS has been observing the sun in X-rays with unprecedented detail. Its goal is to better understand the physics behind phenomena like solar flares – eruptions on the sun that produce dramatic bursts of energy and radiation.

Much of the newly-released radiation from solar flares is concentrated in X-rays, and, in particular, the lower energy range called soft X-rays. But other spacecraft don’t have the capability to measure this part of the sun’s spectrum at high resolution—which is where MinXSS, short for Miniature Solar X-ray Spectrometer, comes in.

Using MinXSS to monitor how the soft X-ray spectrum changes over time, scientists can track changes in the composition in the sun’s corona, the hot outermost layer of the sun. While the sun’s visible surface, the photosphere, is about 6000 Kelvin (10,000 degrees Fahrenheit), areas of the corona reach tens of millions of degrees during a solar flare. But even without a flare, the corona smolders at a million degrees—and no one knows why.

One possibility is that many small nanoflares constantly heat the corona. Or, the heat may come from certain kinds of waves that propagate through the solar plasma. By looking at how the corona’s composition changes, researchers can determine which mechanism is more important, says Tom Woods, a solar scientist at the University of Colorado at Boulder and principal investigator of MinXSS: “It’s helping address this very long-term problem that’s been around for 50 years: how is the corona heated to be so hot.”

The $1 million original mission has been gathering observations since June.

The satellite will likely burn up in Earth’s atmosphere in March. But the researchers have built a second one slated for launch in 2017. MinXSS-2 will watch long-term solar activity—related to the sun’s 11-year sunspot cycle—and how variability in the soft X-ray spectrum affects space weather, which can be a hazard for satellites. So the little-mission-that-could will continue—this time, flying at a higher, polar orbit for about five years.

If you’d like to teach kids about where the sun’s energy comes from, please visit the NASA Space Place: http://spaceplace.nasa.gov/sun-heat/

Astronaut Tim Peake on board the International Space Station captured this image of a CubeSat deployment on May 16, 2016. The bottom-most CubeSat is the NASA-funded MinXSS CubeSat, which observes soft X-rays from the sun—such X-rays can disturb the ionosphere and thereby hamper radio and GPS signals. (The second CubeSat is CADRE — short for CubeSat investigating Atmospheric Density Response to Extreme driving – built by the University of Michigan and funded by the National Science Foundation.) Credit: ESA/NASA

This article is provided by NASA Space Place. With articles, activities, crafts, games, and lesson plans, NASA Space Place encourages everyone to get excited about science and technology. Visit spaceplace.nasa.gov to explore space and Earth science!

Dec 03

What’s Up in the Sky

What’s Up in the Sky – December, 2016

December’s Sky Has Much to Offer

December can be a frustrating month for observing due to its notoriously bad weather, but the legends and lore associated with those hidden sky wonders can add wonder to the season.

Venus is currently doing a good job posing as the Christmas Star albeit in the wrong direction. She, along with two of her companions, Mercury and Mars, can be found all lined up above the southwest horizon after sunset.

Venus is by far the brightest and most easily visible of the three and, in early December, is almost exactly half way in between the others, about twenty degrees (two fists held at arm’s length) from each one. Mercury is to the lower right of Venus, near the southwest horizon, and is rather dim so binoculars or a small telescope will probably be needed to spot it. Mars is to the upper left of Venus and should be easy to see high above the southern horizon.

This week you can also let the crescent Moon be your guide. Keeping in mind the need for a clear horizon and optical aid (binoculars), go out tomorrow around 5:30 p.m. and look for a thin crescent Moon near the southwestern horizon. Mercury will be to its left and even closer to the horizon but on Thursday it will be right below the Moon and both should be a little easier to find.

The following nights the Moon will pass Venus and then, on Sunday, December 4, now approaching first quarter, will be just to the right (west) of Mars. As the month progresses, the Venus-Mars separation will shrink considerably as the two approach a late January close encounter.

You early birds should not feel left out since you have Jupiter dominating the pre dawn sky high in the south. It will be joined by a waning crescent Moon on December 22.

If the weather does not allow these observations, we can always remember the connection between celestial objects and the celebrations of the seasons. Many cultures over the centuries have had stories and legends about this time of year, most concerned with the return of the Sun after the winter solstice. All autumn the Sun sets at a point farther south on the horizon as the days get colder and shorter. Early people were concerned about its return.

Many of our traditions involve the theme of light and have their origins in early rituals meant to coax the Sun back.
The Norsemen of northern Europe used to honor the Sun with a feast called Yule, during which logs of oak were burned. We are still familiar with the Yule log. Candles in windows and luminarias on paths are meant to light the way for Mary and Joseph. Wreaths of holly, with its red berries, were originally used to represent the Sun, and evergreens, with their permanent foliage, were considered symbols of eternal life and assurance of the Sun’s return.

So get out and enjoy the symbols of the Holiday Season that can be found up in the sky.
This month in history:
Dec. 3: Pioneer 10 spacecraft makes closest approach to Jupiter – 1973
Dec. 7: Gerard Kuiper born – 1905
Dec. 14: Gene Cernan, Apollo 17 astronaut, is last human to walk on Moon – 1972
Dec. 20: Founding of Mt. Wilson Solar Observatory – 1904
Dec. 24: Apollo 8 astronauts give us inspirational moment from lunar orbit – 1968
Dec. 25: Isaac Newton born – 1642

Nov 12

Dimming stars, erupting plasma, and beautiful nebulae

By Marcus Woo

Boasting intricate patterns and translucent colors, planetary nebulae are among the most beautiful sights in the universe. How they got their shapes is complicated, but astronomers think they’ve solved part of the mystery—with giant blobs of plasma shooting through space at half a million miles per hour.

Planetary nebulae are shells of gas and dust blown off from a dying, giant star. Most nebulae aren’t spherical, but can have multiple lobes extending from opposite sides—possibly generated by powerful jets erupting from the star.

Using the Hubble Space Telescope, astronomers discovered blobs of plasma that could form some of these lobes. “We’re quite excited about this,” says Raghvendra Sahai, an astronomer at NASA’s Jet Propulsion Laboratory. “Nobody has really been able to come up with a good argument for why we have multipolar nebulae.”

Sahai and his team discovered blobs launching from a red giant star 1,200 light years away, called V Hydrae. The plasma is 17,000 degrees Fahrenheit and spans 40 astronomical units—roughly the distance between the sun and Pluto. The blobs don’t erupt continuously, but once every 8.5 years.

The launching pad of these blobs, the researchers propose, is a smaller, unseen star orbiting V Hydrae. The highly elliptical orbit brings the companion star through the outer layers of the red giant at closest approach. The companion’s gravity pulls plasma from the red giant. The material settles into a disk as it spirals into the companion star, whose magnetic field channels the plasma out from its poles, hurling it into space. This happens once per orbit—every 8.5 years—at closest approach.

When the red giant exhausts its fuel, it will shrink and get very hot, producing ultraviolet radiation that will excite the shell of gas blown off from it in the past. This shell, with cavities carved in it by the cannon-balls that continue to be launched every 8.5 years, will thus become visible as a beautiful bipolar or multipolar planetary nebula.

The astronomers also discovered that the companion’s disk appears to wobble, flinging the cannonballs in one direction during one orbit, and a slightly different one in the next. As a result, every other orbit, the flying blobs block starlight from the red giant, which explains why V Hydrae dims every 17 years. For decades, amateur astronomers have been monitoring this variability, making V Hydrae one of the most well-studied stars.

Because the star fires plasma in the same few directions repeatedly, the blobs would create multiple lobes in the nebula—and a pretty sight for future astronomers.

If you’d like to teach kids about how our sun compares to other stars, please visit the NASA Space Place: http://spaceplace.nasa.gov/sun-compare/en/

This four-panel graphic illustrates how the binary-star system V Hydrae is launching balls of plasma into space. Image credit: NASA/ESA/STScI

This article is provided by NASA Space Place. With articles, activities, crafts, games, and lesson plans, NASA Space Place encourages everyone to get excited about science and technology. Visit spaceplace.nasa.gov to explore space and Earth science!

Older posts «