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Best images! Asteroid 2004 BL86, as it swept near Earth

A video still of asteroid 2004 BL86 and its newly discovered moon from Goldstone Solar System Radar.  The image is from last night (January 25).  Image via Slooh.com.

A video still of asteroid 2004 BL86 and its newly discovered moon from Goldstone Solar System Radar. Image via Slooh.com.

Best images and video of asteroid 2004 BL86, which swept about 3 times the moon’s distance from Earth on Monday, January 26.

Asteroid that flew past Earth on Monday has a moon!

Wow! Scientists working with NASA’s Deep Space Network antenna at Goldstone, California have released the first radar images of asteroid 2004 BL86, which flew closer to Earth on Monday than any asteroid this large will again until the year 2027. The radar images show that the asteroid has its own small moon!

Moon and Aldebaran, former pole star, on January 27

As always, the moon moves eastward through the constellations of the Zodiac. The green line depicts the ecliptic - the sun's annual path in front of the

As always, the moon moves eastward through the constellations of the Zodiac. The green line depicts the ecliptic – the sun’s annual path in front of the “fixed” backdrop stars.

Tonight’s waxing gibbous moon (January 27) is moving toward the star Aldebaran, brightest star in the constellation Taurus the Bull, and the moon will be even closer to this star tomorrow night (January 28). Did you know that Aldebaran is a former pole star? What’s more, at that time, Aldebaran had the company of a fellow bright pole star, Capella.

Big asteroid swept close on January 26

View larger. | The path of asteroid 2004 BL86 on January 26-27 carries it northward among the winter stars and makes it well positioned for viewing with a backyard telescope. Eastern Standard Time is shown, so be sure to make a time-zone correction for your location.  Translate to your time zone here.  Chart via skyandtelescope.com

The path of asteroid 2004 BL86 on January 26-27 carries it northward among the winter stars and makes it well positioned for viewing with a backyard telescope. Eastern Standard Time is shown, so be sure to make a time-zone correction for your location. Translate to your time zone here. Chart via skyandtelescope.com

An asteroid called 2004 BL86 by astronomers – twice as big as a cruise ship – swept safely past Earth today (January 26, 2015). It came closer of any known space rock this large will until asteroid 1999 AN10 flies past Earth in 2027. This was the closest this particular asteroid will come to Earth for at least the next 200 years. Closest approach came at 16:20 UTC, or 11:20 a.m. EST today, when the asteroid was approximately 745,000 miles (1.2 million kilometers) from Earth, or about three times the moon’s distance. If you plan to observe with a small telescope and/or strong binoculars, the night of January 26-27 is the best time! Plus some online observations of it are still to come. And professional astronomers will be watching in the days ahead. Even at its peak brightness, the asteroid will not be bright enough to view with the unaided eye. But you can watch with optical aid, or online. Follow the links inside for more.

How do snowflakes get their shape?

Photo by EarthSky Facebook friend Paula Lancaster Lupi of a snowflake and frost on her car window.

The shape of snowflakes is influenced by the temperature and humidity of the atmosphere.

How to take photos of snowflakes

Snowflake from Trillemarka, Sigdal. Photo by EarthSky Facebook friend Jånn Peter Normann. Thank you Jånn!

An upside of a snowstorm: Pictures of snowflakes! Here’s a post to help you learn to take your own photos of snowflakes.

The intriguing crack in Rosetta’s comet, and more

This image from Rosetta’s OSIRIS narrow-angle camera shows part of a large fracture in the neck of comet 67P/Churyumov-Gerasimenko.  Image via ESA/Rosetta/MPS for OSIRIS Team.

This image from Rosetta’s OSIRIS narrow-angle camera shows part of a large fracture in the neck of comet 67P/Churyumov-Gerasimenko. Image via ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

After the excitement of the Rosetta spaceraft’s rendezvous with its – then its little Philae lander’s bounce across the comet’s surface in November – you might think things couldn’t get more interesting for this wonderful European Space Agency (ESA) comet mission. But now they have. In a special edition of the journal Science, scientists have released results from seven of Rosetta’s 11 science instruments. Among the most fascinating of the newly announced results is a prominent and intriguing 500-meter-long crack – as long as five American football fields – between the two lobes of the comet, running roughly parallel to the comet’s neck. Plus dust and jets, the mysterious double-lobed shape, and more.

Seasons are changing on Rosetta’s comet

Via ESA NAVCAM Rosetta.

Rosetta obtained this image of its comet on January 16. Contrast it to an image inside, and you’ll see how the “seasons” are changing on the comet. Image via ESA NAVCAM Rosetta.

While its Philae Lander continues to ‘sleep,’ waiting for the sun to rise high enough in its sky for its solar panels to begin generating power again, the Rosetta spacecraft continues its science mission at Comet 67P/Churyumov–Gerasimenko. The image above is an amazing four-frame mosaic from Rosetta’s Navigation Camera (NAVCAM), taken on January 16. The orientation of the Rosetta Spacecraft and time of day on the comet is identical to the images obtained back on November 2. Click inside and compare …

Use brightest star Sirius to imagine sun’s path through Milky Way

Not sure which star is Sirius? The three Belt stars of Orion – three stars in a short, straight row – always point to Sirius.

You can use the brilliant star Sirius to imagine the direction our sun and solar system are traveling through space. The sun in its orbit is traveling away from Sirus and toward the star Vega (which shines over the northwest horizon – opposite Sirius – at this time of year). So if you stand outside in the evening with your back to Sirius – facing northwest – you’ll be facing the direction our solar system moves through the Milky Way galaxy.

What’s a safe distance between us and an exploding star?

Artist's illusration of a supernova via SmithsonianScience.org

Artist’s illustration of a supernova via SmithsonianScience.org

A supernova is a star explosion – destructive on a scale almost beyond human imagining. If our sun exploded as a supernova, the resulting shock wave probably wouldn’t destroy the whole Earth, but the side of Earth facing the sun would boil away. Clearly, the sun’s distance – 8 light-minutes away – isn’t safe. Fortunately, our sun isn’t the sort of star destined to explode as a supernova. But other stars, beyond our solar system, will. What is the closest safe distance? Follow the links inside to learn more.