Comet Siding Spring’s Path

The orbit of comet C/2013 A1 Siding Spring up to the close pass of Mars on 19 Oct 2014. Image Credit: NASA/JPL-Caltech

The orbit of comet C/2013 A1 Siding Spring up to the close pass of Mars on 19 Oct 2014. Image Credit: NASA/JPL-Caltech

I was looking all over for a graphic on the Mars encounter last Thursday and NASA published this on Friday. Great timing! So now I need to figure out if the comet might be visible with a telescope. Could be, the moon won’t be a factor and Mars should be visible for a time after sunset. I just need to upload the ephemeris for Siding Spring into Stellarium.

One thing I will be able to see (and so will you) on that night is Venus and Spica very close together — easy to see too. More about that later on.

NASA on the visit:

NASA is taking steps to protect its Mars orbiters, while preserving opportunities to gather valuable scientific data, as Comet C/2013 A1 Siding Spring heads toward a close flyby of Mars on Oct. 19.

 

The comet’s nucleus will miss Mars by about 82,000 miles (132,000 kilometers), shedding material hurtling at about 35 miles (56 kilometers) per second, relative to Mars and Mars-orbiting spacecraft. At that velocity, even the smallest particle — estimated to be about one-fiftieth of an inch (half a millimeter) across — could cause significant damage to a spacecraft.

Read the rest at NASA.

Antares and a Supermoon

Antares rocket and a supermoon on Saturday.  Image Credit: NASA/Aubrey Gemignani

Antares rocket and a supermoon on Saturday. Image Credit: NASA/Aubrey Gemignani

Nice picture from NASA of the Super Moon setting over the Orbital Science Antares rocket with the Cygnus cargo ship ready for flight. See the original here (suitable for a nice desktop).

The Antares did launch successfully today. Nice launch too, although I admit to doing the same thing as the last launch: as the Antares first leaves the pad, I’m saying ” come on, come on – get up there you can do it”. There is a (short) time where it looks like the rocket is just able to lift itself, a short time, yes but long enough to get me wondering! Here’s a replay if you missed it. So far everything looks great with Cygnus.

Now hopefully you got a look at the nice full moon we had. It was really quite spectacular. This full moon was just one of three in a row. Yes! August and September will also have the perigee “Supermoons”.

Here is a NASA ScienceCast video explaining the Supermoons.

HAPPY SOLSTICE!!

Summer for some (including me) and winter for others “officially” arrived at 10:51 UTC (06:51 EDT).

Funny, I seem to notice the morning shadows as much as the extra daylight. I think it is because the sun rises northeasterly enough to clear the mountains earlier than normal thank to hitting a low spot in the hills. This means the sun is at a lower angle, thus longer shadows and it does this for a very short time – only a couple weeks. “Normally” the sun has to be pretty high before the sun hits here, being relatively close to the mountains. It’s light of course but direct sunlight has to move in from the west as the Sun climbs.

At any rate I kind of liked this time lapse from Anchorage Alaska. I should try this, maybe Sunday. An image every half hour? I bet I can find some weather cams to capture image frames from. The video was from 2012 and runs from 1930 on 21 Jun to 00:40 on 24 Jun.

Source

LDSD Update

Here is the The launch tower that will help the Low-Density Supersonic Decelerator test vehicle to a balloon.  Image Credit: NASA/JPL-Caltech

Here is the The launch tower that will help the Low-Density Supersonic Decelerator test vehicle to a balloon. Image Credit: NASA/JPL-Caltech

NASA’s Low-Density Supersonic Decelerator (LDSD) launch has been put off until some other time after 14 June (Saturday) due to weather.

Launching is not as easy as just waiting out the weather. This from NASA’s LDSD Launch Status Updates: “NASA will research range availability for the coming weeks and the costs associated with extending the test flight period for launching LDSD’s high-altitude balloon and test vehicle, with programmatic decisions required to proceed.”.

 

 

Simulated Neutron Stars Collision

This description from NASA’s Goddard Space Fight Center (click for source):

This supercomputer simulation shows one of the most violent events in the universe: a pair of neutron stars colliding, merging and forming a black hole.

 

A neutron star is the compressed core left behind when a star born with between eight and 30 times the sun’s mass explodes as a supernova. Neutron stars pack about 1.5 times the mass of the sun — equivalent to about half a million Earths — into a ball just 12 miles (20 km) across.

As the simulation begins, we view an unequally matched pair of neutron stars weighing 1.4 and 1.7 solar masses. They are separated by only about 11 miles, slightly less distance than their own diameters. Redder colors show regions of progressively lower density.

As the stars spiral toward each other, intense tides begin to deform them, possibly cracking their crusts. Neutron stars possess incredible density, but their surfaces are comparatively thin, with densities about a million times greater than gold. Their interiors crush matter to a much greater degree densities rise by 100 million times in their centers. To begin to imagine such mind-boggling densities, consider that a cubic centimeter of neutron star matter outweighs Mount Everest.

By 7 milliseconds, tidal forces overwhelm and shatter the lesser star. Its superdense contents erupt into the system and curl a spiral arm of incredibly hot material. At 13 milliseconds, the more massive star has accumulated too much mass to support it against gravity and collapses, and a new black hole is born. The black hole’s event horizon — its point of no return — is shown by the gray sphere. While most of the matter from both neutron stars will fall into the black hole, some of the less dense, faster moving matter manages to orbit around it, quickly forming a large and rapidly rotating torus. This torus extends for about 124 miles (200 km) and contains the equivalent of 1/5th the mass of our sun.

Scientists think neutron star mergers like this produce short gamma-ray bursts (GRBs). Short GRBs last less than two seconds yet unleash as much energy as all the stars in our galaxy produce over one year.

The rapidly fading afterglow of these explosions presents a challenge to astronomers. A key element in understanding GRBs is getting instruments on large ground-based telescopes to capture afterglows as soon as possible after the burst. The rapid notification and accurate positions provided by NASA’s Swift mission creates a vibrant synergy with ground-based observatories that has led to dramatically improved understanding of GRBs, especially for short bursts.

By 7 milliseconds, tidal forces overwhelm and shatter the lesser star. Its superdense contents erupt into the system and curl a spiral arm of incredibly hot material. At 13 milliseconds, the more massive star has accumulated too much mass to support it against gravity and collapses, and a new black hole is born. The black hole’s event horizon — its point of no return — is shown by the gray sphere. While most of the matter from both neutron stars will fall into the black hole, some of the less dense, faster moving matter manages to orbit around it, quickly forming a large and rapidly rotating torus. This torus extends for about 124 miles (200 km) and contains the equivalent of 1/5th the mass of Continue reading

LADEE Interfaces with Moon

Artist concept of LADEE.  Image Credit: NASA Ames/Dana Berry

Artist concept of LADEE. Image Credit: NASA Ames/Dana Berry

The Lunar Atmosphere and Dust Environment Explorer (LADEE) interfaced with lunar surface, NASA speak for it hit the moon – hard.

The impact occurred between 21:30 and 22:22 PDT on 17 April. Not bad, my guess was 19:20 on 18 April.

I was kind of hoping to hear where it hit this weekend, apparently I was over-simplifying things. The spacecraft was moving about 5,800 kmh or 3,600 mph. Not likely to be anything recognizable on the surface except for small impact craters.

We might get a good look at the impact site from the Lunar Reconnaissance Orbiter Camera as soon as mission managers figure out where it ended up and a LRO pass will occur.

The LADEE mission end at NASA.

It’s Spring!

Today is the March Equinox. Finally! The equinox occurred at 16:57 UTC.

For me, the winter has been long and cold, March alone has been 12 oC below normal. In fact it is still cold. Maple syrup producers have hardly made a drop so far.

A cartoon depicting the angle of sunlight lighting the Earth’s surface. Image by Przemyslaw “Blueshade” Idzkiewicz.

So the March equinox heralds longer days for the northern hemisphere and shorter days for the south. On the day of the equinox the tilt of the Earth is more or less balanced as you can see in the cartoon above.

Equinox

late 14c., from Old French equinoce (12c.) or directly from Medieval Latin equinoxium “equality of night (and day),” from Latin aequinoctium “the equinoxes,” from aequus “equal” (see equal (adj.)) + nox (genitive noctis) “night” (see night). The Old English translation was efnniht. Related: Equinoctial.

- Online Etymology Dictionary

Most of you have no doubt noticed the date of equal and night does not necessarily occur on the equinox (today for example). The day that comes the closest to 12 hours day and night depends on your latitude. For my latitude (~45 N) that day was this past Monday.  Here is a good explanation of why.

The image below attempts to show this day length / latitude relationship, and while it isn’t down to the minute or anything, it depicts how things progress during the year. That and I liked it.

Amount of daylight through the year at different latitudes. Image: Creative Commons

 I did not see the onslaught of feats of egg balancing on the equinox this year! :mrgreen: