Astrotidbits-blog - Astrotidbits.info

Amédée Guillemin, Les comètes (1875)

Orbital Symphony

What Happened to Mars?

Billions of years ago, Mars was a very different world. Liquid water flowed in long rivers that emptied into lakes and shallow seas. A thick atmosphere blanketed the planet and kept it warm.

Today, Mars is bitter cold. The Red Planet’s thin and wispy atmosphere provides scant cover for the surface below.

Our MAVEN Mission

The Mars Atmosphere and Volatile EvolutioN (MAVEN) mission is part of our Mars Scout program. This spacecraft launched in November 2013, and is exploring the Red Planet’s upper atmosphere, ionosphere and interactions with the sun and solar wind.

The purpose of the MAVEN mission is to determine the state of the upper atmosphere of Mars, the processes that control it and the overall atmospheric loss that is currently occurring. Specifically, MAVEN is exploring the processes through which the top of the Martian atmosphere can be lost to space. Scientists think that this loss could be important in explaining the changes in the climate of Mars that have occurred over the last four billion years.

New Findings

Today, Nov. 5, we will share new details of key science findings from our ongoing exploration of Mars during a news briefing at 2 p.m. EDT. This event will be broadcast live on NASA Television. Have questions? Use #askNASA during the briefing.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com 

What’s Up for March 2017?

What’s Up for March? The moon hides red star Aldebaran and crescents dazzle after dusk.

On March 4 the first quarter moon passes between Earth and the star Aldebaran, temporarily blocking our view of the star. This is called an occultation. 

The occultation begins and concludes at different times, depending on where you are when you view it.

The event should be easy to see from most of the U.S., Mexico, most of Central America, the Western Caribbean and Bermuda. 

Observers along a narrow path from Vancouver, British Columbia, to Hartford, Connecticut, will see the moon “graze” the star. The star will disappear and reappear repeatedly as hills and valleys on the moon alternately obscure and reveal it.

As seen from Earth, both Mercury and Venus have phases like our moon. That’s because they circle the sun inside Earth’s orbit. 

Planets that orbit between Earth and the sun are known as inner or inferior planets.

Inferior planets can never be at “opposition,” which is when the planet and the sun are on opposite sides of Earth.

But inferior planets can be at “conjunction,” which is when a planet, the sun and Earth are all in a straight line. 

Conjunction can happen once when the planet is on the opposite side of the sun from Earth and again when it’s on the same side of the sun as Earth. 

When a planet is on the opposite side of the sun from Earth, we say it is at “superior conjunction.” As the planet moves out from behind the sun and gets closer to Earth, we see less and less of the lit side. We see phases, similar to our moon’s phases. 

Mercury is at superior conjunction on March 6. 

A few weeks later, the planet emerges from behind the sun and we can once again observe it. By the end of March we’ll see a last-quarter Mercury.

 On April 20 Mercury reaches “inferior conjunction.”

Brilliant Venus is also racing toward its own inferior conjunction on March 25. Watch its crescent get thinner and thinner as the planet’s size appears larger and larger, because it is getting closer to Earth.

Finally, look for Jupiter to rise in the East. It will be visible all month long from late evening until dawn.

You can catch up on solar system missions and all of our missions at www.nasa.gov

Watch the full “What’s Up for March 2017″ video here: 

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com

The orbit of Jupiter protects the Earth from asteroids.

Explain this to me...

“Quantum cryptography uses the quantum properties of photons to guarantee perfect secrecy. But one of its lesser known limitations is that it only works if Alice and Bob are perfectly aligned so that they can carry out well-defined polarization measurements on the photons as they arrive. Physicists say that Alice and Bob must share the same reference frame. That’s OK if Alice and Bob are in their own ground-based labs, but it’s a problem in many other applications, such as ground-to-satellite communications or even in chip-to-chip communications, because it’s hard to keep chips still over distances of the order of the wavelength of light. Now a group of UK physicists have developed a way of doing quantum cryptography without sharing a reference frame. The trick is to use entangled triplets of photons, so-called qutrits, rather than entangled pairs. This solves the problem by embedding it in an extra abstract dimension, which is independent of space. So, as long as both Alice and Bob know the way in which all these abstract dimensions are related, the third provides a reference against which measurements of the other two can be made. That allows Alice and Bob to make any measurements they need without having to agree ahead of time on a frame of reference. That could be an important advance enabling the widespread use of quantum cryptography.”

Will Jupiter’s Great Red Spot turn into a wee red dot? by BOB KING

Watch out! One day it may just go away. Jupiter’s most celebrated atmospheric beauty mark, the Great Red Spot (GRS), has been shrinking for years.  When I was a kid in the ’60s peering through my Edmund 6-inch reflector, not only was the Spot decidedly red, but it was extremely easy to see. Back then it really did span three Earths. Not anymore. 

In the 1880s the GRS resembled a huge blimp gliding high above white crystalline clouds of ammonia and spanned 40,000 km (25, 000 miles) across. You couldn’t miss it even in those small brass refractors that were the standard amateur observing gear back in the day. Nearly one hundred years later in 1979, the Spot’s north-south extent has remained virtually unchanged, but it’s girth had shrunk to 25,000 km (15,535 miles) or just shy of two Earth diameters. Recent work done by expert astrophotographer Damian Peach using the WINJUPOS program to precisely measure the GRS in high resolution photos over the past 10 years indicates a continued steady shrinkage:

2003 Feb – 18,420km (11,445 miles)

2005 Apr – 18,000km (11,184)

2010 Sep – 17,624km (10,951)

2013 Jan – 16,954km (10,534)

2013 Sep – 15,894km (9,876)

2013 Dec – 15,302km (9,508) = 1.2 Earth diameters

If these figures stand up to professional scrutiny, it make one wonder how long the spot will continue to be a planetary highlight. It also helps explain why it’s  become rather difficult to see in smaller telescopes in recent years. Yes, it’s been paler than normal and that’s played a big part, but combine pallor with a hundred-plus years of downsizing and it’s no wonder beginning amateur astronomers often struggle to locate the Spot in smaller telescopes. This observing season the Spot has developed a more pronounced red color, but unless you know what to look for, you may miss it entirely unless the local atmospheric seeing is excellent.

Not only has the Spot been shrinking, its rotation period has been speeding up.  Older references give the period of one rotation at 6 days. John Rogers (British Astronomical Assn.) published a 2012 paper on the evolution of the GRS and discovered that between 2006 to 2012 – the same time as the Spot has been steadily shrinking – its rotation period has spun up to 4 days. As it shrinks, the storm appears to be conserving angular momentum by spinning faster the same way an ice skater spins up when she pulls in her arms.

Rogers also estimated a max wind speed of 300 mph, up from about 250 mph in 2006.  Despite its smaller girth, this Jovian hurricane’s winds pack more punch than ever. Even more fascinating, the Great Red Spot may have even disappeared altogether from 1713 to 1830 before reappearing in 1831 as a long, pale “hollow”. According to Rogers, no observations or sketches of that era mention it. Surely something so prominent wouldn’t be missed. This begs the question of what happened in 1831. Was the “hollow” the genesis of a brand new Red Spot unrelated to the one first seen by astronomer Giovanni Cassini in 1665? Or was it the resurgence of Cassini’s Spot?

Clearly, the GRS waxes and wanes but exactly what makes it persist? By all accounts, it should have dissipated after just a few decades in Jupiter’s turbulent environment, but a new model developed by Pedram Hassanzadeh, a postdoctoral fellow at Harvard University, and Philip Marcus, a professor of fluid dynamics at the University of California-Berkeley, may help to explain its longevity.  At least three factors appear to be at play:

* Jupiter has no land masses. Once a large storm forms, it can sustain itself for much longer than a hurricane on Earth, which plays itself out soon after making landfall.

* Eat or be eaten: A large vortex or whirlpool like the GRS can merge with and absorb energy from numerous smaller vortices carried along by the jet streams.

* In the Hassanzadeh and Marcus model, as the storm loses energy, it’s rejuvenated by vertical winds that transport hot and cold gases in and out of the Spot, restoring its energy. Their model also predicts radial or converging winds within the Spot that suck air from neighboring jet streams toward its center. The energy gained sustains the GRS.

If the shrinkage continues, “Great” may soon have to be dropped from the Red Spot’s title. In the meantime, Oval BA (nicknamed Red Spot Jr.) and about half the size of the GRS, waits in the wings. Located along the edge of the South Temperate Belt on the opposite side of the planet from the GRS, Oval BA formed from the merger of three smaller white ovals between 1998 and 2000. Will it give the hallowed storm a run for its money? We’ll be watching.

At left, photo of Jupiter’s enormous Great Red Spot in 1879 from Agnes Clerk’s Book ” A History of Astronomy in the 19th Century”. At right, Jupiter on Jan. 10, 2014. Credit: Damian Peach

Discover Bird Photo Booth, the world’s first wireless bird feeder and birdcam. Get more information here

Last space shuttle External Tank arrives at California Science Center.

ET-94 paraded its way through the Los Angeles suburbs today, May 21, as it journeyed to its final home at the California Science Center.

The last surviving flight-worthy space shuttle external tank, ET-94 left the Michoud Assembly Facility in New Orleans April 12, where it has been since it was fabricated in the early 2000′s. It traversed the Panama Canal April 25-27, and arrived at Marina Del Rey in Los Angeles last Wednesday, May 19, after a 36-day sea voyage.

Leaving Marina Del Rey at 12:01am PDT with a New Orleans jazz band, the tank encountered more obstacles than expected during its 15.5 mile trek through the city, arriving at the CSC at 7:13pm PDT.

Towed through the streets of Inglewood, the last time space hardware shut down traffic was in October 2012, when space shuttle Endeavour was towed from Los Angeles International Airport to the CSC.

P/c: LA Times, California Science Center.