Tag: astronomy

Linking mass extinctions to the Sun’s journey in the Milky Way

12:53 pm

The Sun's orbit in the Milky Way

In a paper published today on the Los Alamos astro-ph preprint service, astronomers propose that as many as eleven past extinction events can be linked to the Sun’s passage through the spiral arms of the Milky Way. (You can download the paper here [pdf].)

A correlation was found between the times at which the Sun crosses the spiral arms and six known mass extinction events. Furthermore, we identify five additional historical mass extinction events that might be explained by the motion of the Sun around our Galaxy. These five additional significant drops in marine genera that we find include significant reductions in diversity at 415, 322, 300, 145 and 33 Myr ago. Our simulations indicate that the Sun has spent ~60% of its time passing through our Galaxy’s various spiral arms.

The figure on the right, from their paper, shows the Sun’s orbit in red over the last half billion years. The Sun’s present position is indicated by the yellow spot, and the eleven extinctions are indicated by the circles.

There are obviously a great deal of uncertainties in this conclusion. Most significantly, the shape and history of the Milky Way remains very much in doubt, especially since we reside within it and cannot really get a good look at it. Though in recent years astronomers have assembled a reasonable image of the galaxy’s shape — a barred spiral with two major arms and several minor ones — this picture includes many assumptions that could very easily be wrong.

Nonetheless, the paper’s conclusions are interesting.
» Read more

7 comments

Voyager 1’s future.

9:08 am

Voyager 1’s future.

Voyager 1 has enough nuclear fuel to keep doing science through to 2025, and then it will be dead, adrift. On its current trajectory, the probe should eventually end up within 1.5 light years of a star in Camelopardalis, a northern constellation that looks like a cross between a giraffe and a camel. No one knows if there are any planets around that star, nor if aliens will be in residence by the time the probe arrives. “But if they are there, maybe they will capture Voyager 1,” says mission scientist Tom Krimigis of Johns Hopkins University in Baltimore, Maryland.

In addition to the above silliness, the article gives a good summary of the real data that Voyager 1 is sending back about interstellar space.

0 comments

NASA has announced a press conference for later today about the Voyager spacecraft.

9:26 am

NASA has announced a press conference for later today about the Voyager spacecraft.

The rumors are that all the scientists involved with this data from this spacecraft now finally agree that Voyager has left the solar system. More to come.

The rumors were true: NASA has confirmed that Voyager 1 is out of the solar system and in interstellar space, and has been since last summer.

3 comments

Astronomers have compiled the first detailed 3D map of the inner regions of the Milky Way.

9:08 am

Astronomers have compiled the first detailed 3D map of the inner regions of the Milky Way. More here.

They find a box/peanut shaped bulge with an elongated bar and a prominent X-structure, which had been hinted at in previous studies. This indicates that the Milky Way was originally a pure disk of stars, which then formed a thin bar, before buckling into the box/peanut shape seen today.

0 comments

Astronomers submit a slew of proposals for using the partly crippled Kepler space telescope.

3:32 pm

Astronomers submit a slew of proposals for using the partly crippled Kepler space telescope.

Ideas range from a survey of potentially hazardous near-Earth objects to a study of Jupiter-sized exoplanets in large orbits. Kepler scientists will sort through the proposals and decide by 1 November which ones, if any, to recommend to NASA headquarters for further review.

Sadly, none of these ideas excites me very much. The tragedy here is that we have this really good optical telescope above the atmosphere, and we can’t point it accurately enough to use it.

2 comments

NASA will reactivate the Wide-field Infrared Survey Explorer (WISE) next month to use it to look for more near Earth asteroids.

4:48 pm

NASA will reactivate the Wide-field Infrared Survey Explorer (WISE) next month to use it to look for more near Earth asteroids.

This decision raises two thoughts.

  • Why did they shut it down in the first place if it was still viable and could still do important research? If the cost wasn’t worth the benefit then, how has this equation changed now? And if the cost was worth the benefit, it then was foolish to shut it down in the first place. Though it costs money to operate these things, it is always cheaper to keep something running than to build something new. The press announcement above doesn’t really address these issues, and I wish it did.
  • I wonder if this decision is somehow related to the end of the Kepler mission. With Kepler out of service, maybe NASA decided to shift the funds to run that telescope over to WISE. They do not say, but the timing is interesting. This decision could be a hint that Kepler doesn’t really have another mission it can fulfill, and thus the money to run it has already been put elsewhere.
0 comments

A star that went nova last week is now visible to the naked eye.

2:07 pm

A star that went nova last week is now visible to the naked eye.

“Nova Delphini 2013 is among the 30 brightest novae ever recorded,” says S&T editor in chief Robert Naeye. “It’s a wonderful target for backyard observers, given that it’s visible to the naked eye and relatively easy to find. But it’s also attracting the intense interest of scientists, who are using a wide assortment of telescopes and astronomical satellites to better understand these enigmatic explosions.”

Though related scientifically to certain kinds of supernovae, this is not a supernova. Nonetheless, it is rare for these events to be bright enough to be visible to the naked eye. Go outside tonight and take a look!

3 comments
1 … 79 80 81 82 83 … 113