Newest of new moons

By Phil Plait | May 5, 2008 7:33 pm

Update: I have posted an updated version of this story, along with an incredible picture of the crescent Moon just 10 minutes before it was new.

Not a world-stopping bit of news, but cool and interesting: the youngest new Moon ever has been spotted. It was so young, in fact, that it was actually not yet quite new.

Here’s the deal: the Moon goes around the Earth (stop me if I’m going too fast). Once every orbit (roughly once per month) it passes near the Sun in the sky. The Moon’s orbit is tilted with respect to the Earth’s around the Sun, so it doesn’t pass directly in front of the Sun every orbit, and sometimes it’s farther "above" or "below" the Sun in the sky than other times.

The Moon is officially new once it passes that closest point to the Sun in the sky. But think about it: it passes very close to the Sun (never more than 5 degrees, about the width of three or so fingers held at arms length). That means you have to do this observation while the Sun is up! Or just after it sets. Either way, this is no small thing.

So what Martin Elsässer did was see the Moon before it actually passed the Sun, just five minutes before it was new.

So I guess what he saw was the oldest old Moon, but close enough. There is a sortof sport among some astronomers to spot the youngest Moon, and Martin Elsässer has set that bar considerably higher. This picture, from Herr Elsässer’s site itself, shows why this is such a difficult task:

That image was taken when the Moon was still 19 degrees from the Sun. Imagine when it’s 5 degrees! So hats off to Herr Elsässer. That’s an amazing feat.

CATEGORIZED UNDER: Astronomy, Cool stuff

Comments (21)

  1. Wow! If he’d waited 5 more minutes to snap his photo he’d have a record that would have to stand -FOREVER- !!! (in a way) Untill someone got it at a smaller angular separation.

    Our Iranian colleagues are big into this stuff. I bet they’ll work on it!
    Rich in Charlottesville

  2. Cameron

    Richard: “Untill someone got it at a smaller angular separation.”

    Isn’t that a solar eclipse?

  3. Cameron:
    18 degrees would be closer. You wouldn’t have to go all the way to eclipse. The Iranians are into young Moon spotting because that is used to start a holiday (Ramadan, I think). The Moon-spotter gets bragging rights for the year! They’re into BIG binocs.

  4. wil

    So . . . would this be a New Moon on Monday?


  5. Max Fagin

    “never more than 5 degrees, about the width of three or so fingers held at arms length.”

    What about during a solar eclipse? Isn’t that 5 degrees closer than 5 degrees?

  6. I saw a picture like this a few weeks ago. Took me a long time to see the moon in the last one.

    Science is great.

  7. Alex

    That picture reminds me of the two sun scene in the first Star Wars movie.

  8. Buzz Parsec

    Max … “never more than” means “not (greater than)” which means “less than or equal”, so 0 degrees (eclipse) is less than 5 degrees (maximum separation at new moon), which is what BA said.

    Richard and Cameron, the picture is at 19 degrees, but the observation was at 5 minutes before new moon, which is no more than 5 degrees. (Following the links from the story, the moon was 4.57 degrees from the sun at conjunction. 5 minutes earlier, judging by the graph, it wasn’t much farther away, no more than 4.6 degrees.) Other new moons will be significantly closer (less than .5 degree for a partial solar eclipse, less than .02 degree for a total eclipse.) The separation depends on your location on earth at the time. Also, the new moon doesn’t necessarily occur at the moment of least separation… I’m pretty sure the new moon is defined as the least separation of the center of the moon from the line between the center of the earth and the center of the sun, and from any point 4000 miles away from the center of the earth (i.e. on the surface of the earth), there may be a significant parallax.

    (The moment of new moon may actually be defined as the moment the center of the moon has the same RA as the center of the Sun, or the moment it’s at the same ecliptic longitude… which could shift the time of new moon by an hour or so from the moment of closest approach.)

    It wasn’t clear to me if this was a visual observation, or the result of extreme image processing (e.g. turning up the contrast knob in Photoshop to 11.)

    The article describes this as the best opportunity for a close new moon observation from Europe this year. I couldn’t tell if this was due to the separation or the timing or the elevation of the moon in the sky at the time of new moon, or some combination of the three factors, or something else entirely.

    I think the official Moslem calendar definition of the start of a month is the 1st evening that the new moon is visible from Mecca. Some months are easy, one day is before new moon, or such a short time after that there is no way it could be seen, but the next day, it will be easy to see. Other months are dodgy, they really have to wait and see, so they publish provisional calendars where month X might be either 28 or 29 days long, and month X+1 might start a day earlier or later. You have to wait for the announcement, and adjust. Since this determines the date of some religious events (e.g. Ramadan), some years they don’t know precisely when they will occur. I think only naked eye observations count for this purpose.

    A very thin crescent moon can be very hard to detect in daylight. One bitterly cold December morning several years ago, just at the start of twilight, I saw Venus shining brilliantly below a very thin crescent moon. I though this would be a good chance to spot Venus in full daylight, so I went outside about an hour later, and it took me a good 10 minutes to find the moon! (And the sky was crystal clear.) Once I spotted it, it only took a second or two to see Venus as a bright, reddish yellow (due to contrast with the bright blue sky?) spark just below it. I looked back at the Sun to make sure it had really risen (it had, about 10 minutes earlier), and this time it only took a few seconds to spot the Moon and Venus again. Then I went inside before succumbing to hypothermia.

  9. Thomas Siefert

    The Iranians are into young Moon spotting because that is used to start a holiday (Ramadan, I think). The Moon-spotter gets bragging rights for the year!

    More importantly, it also marks the end of the Ramadan when the Muslims (not just Iranians) can start eating during the day again.
    Because a cloud cover can delay the sighting of the new Moon by a day or more, the Moon-spotter will be the hero of the day.

    This was all explained to my wife and I by a Muslim taxi driver in Malaysia, no doubt prompted by the smells emanating from the bag of chicken take-away that we had bought from a street vendor and taken into his taxi on one of the last days of the Ramadan.

  10. jest

    I just love the simplicity of the whole thing. No need to leave the general vicinity of the planet to get some truly stunning and challenging shots.

    I saw a very young sliver of a moon last month, and though it was nowhere near the “youth” of this shot, it was still really cool to see.

  11. morley kabernick

    HOLY CRAP…… it’s wil weaton! *points up*

    Now for something entierly different

    Yesterdays Tomorrow…. TODAY!…. har.

  12. Michelle

    Just saw the picture… It’s a whole lot of noise but wow! Nice!

  13. BA says:

    it passes very close to the Sun (never more than 5 degrees


    That image was taken when the Moon was still 19 degrees from the Sun

    Link says:

    he got the Moon five minutes before new

    Something doesn’t add up.

    If “new” is “never more than 5 degrees” from the Sun, and this photo is “five minutes before new” yet “19 degrees from the Sun”, that implies the Moon travels at least 14 degrees in five minutes, or slightly over 2 hours to go 360 degrees!

  14. Richard B. Drumm:

    If he’d waited 5 more minutes to snap his photo he’d have a record that would have to stand -FOREVER- !!!

    The linked article says:

    And if there hadn’t been a “Schweinewolke” at the wrong moment, the first-ever image of the crescent at the very moment of new moon would have been no problem, too.

    (So, what does “Schweinewolke” mean? A literal translation is “pig cloud”.)

  15. @Ken B: “That image was taken when the Moon was still 19 degrees from the Sun… he got the Moon five minutes before new”

    The image BA displayed in his post was taken 19 degrees from the sun. This *isn’t* the same image that was taken five minutes before new. THat image is here:

    As for schweinewolke, it’s definitely something cloud-related — the English page I linked to in my previous post (see above) says the following:

    “Though clouds moved in, we managed to capture the crescent up till 14:13 CEST (UT+2), only 5 minutes from conjunction, at an elongation of 4.58°. … Due to clouds, the earliest image after conjunction was not made before 15:02 CEST, some 44 minutes after conjunction. The rotation of the crescent is well visible, when comparing with earlier images.”

  16. Gnat

    On a purely asctetic note: the colors are absolutely beautiful! It’s my new background!

  17. tony873004

    During a solar eclipse, features on the Moon’s dark side can be seen. Why doesn’t this count as the record?

  18. puckchaser

    I would have taken a video, and then a screen cap …. just sayin..

  19. Of course we knew about the time of new-moon (several different definitions are available) but due to clouds we could not quite acchieve the “NULL”.

    “Schweinewolke” is a derogatory term for the very cloud which prevented the NULL and could be translated as “pig-cloud” (not meaning to insult any pigs, of course.)

    The images are processed images: Adding about 100 images from a videostream, applying a flat-field, applying a auto-flat, adjusting contrast and brightness.

    The brightest part of the crescent was about 0.3% brighter than the background sky (foreground actually), as measured from the best image, some hours before new.


Discover's Newsletter

Sign up to get the latest science news delivered weekly right to your inbox!


See More

Collapse bottom bar