La astronomo ĉeestas la kunvenon.

A word-by-word breakdown is:

• la = the
• astronomo = astronomer
• ĉeestas = is present at / attends
• la = the
• kunvenon = meeting (with -n, marking it as the direct object)

So the sentence means something like The astronomer is attending the meeting or The astronomer is present at the meeting.

In Esperanto, la is the definite article, meaning the.

It appears before both nouns because both are definite:

• la astronomo = the astronomer
• la kunvenon = the meeting

Unlike English, Esperanto has only one article form: la. It does not change for gender, number, or case.

The -n ending marks the direct object.

Here, the verb ĉeesti takes a direct object, so the meeting gets -n:

• La astronomo ĉeestas la kunvenon.

That means the astronomer is the one doing the action, and the meeting is what is being attended.

This is very common in Esperanto:

• Mi vidas la hundon. = I see the dog.
• Ŝi legas la libron. = She reads the book.

So here:

• kunveno = meeting
• kunvenon = meeting as the direct object

Because astronomo is the subject, not the direct object.

In Esperanto, the subject usually has no special ending, while the direct object gets -n.

So in this sentence:

• La astronomo = the subject
• la kunvenon = the direct object

That is how you know the astronomer is attending the meeting, not the other way around.

-as is the present-tense ending in Esperanto.

So ĉeestas is present tense:

• ĉeestas = attends / is attending / is present at

Esperanto present tense is often broader than English. Depending on context, it can translate as:

• attends
• is attending
• is present at

Esperanto does not force the same continuous vs. simple distinction that English does.

Yes, ĉeestas is one verb.

It comes from:

• ĉe = at, by
• esti = to be

Together, ĉeesti means to be present at or to attend.

So although it looks like ĉe + estas, you should learn ĉeesti as a normal dictionary verb:

• ĉeesti = to attend
• ĉeestas = attends / is attending
• ĉeestis = attended
• ĉeestos = will attend

Because ĉeesti normally takes a direct object in Esperanto.

So you say:

• ĉeesti kunvenon = to attend a meeting

not:

• ĉeesti al kunveno

This is something you simply learn with the verb. Even though English uses attend directly too, learners sometimes expect a preposition because the idea is be present at. In Esperanto, the usual pattern is still direct object + -n.

Yes, Esperanto word order is fairly flexible, mainly because -n helps show what the object is.

The most neutral order is:

• La astronomo ĉeestas la kunvenon.

But you could also say:

• La kunvenon ĉeestas la astronomo.

That still means The astronomer is attending the meeting, because kunvenon has -n, so it is still the object.

However, the original order is the most natural in ordinary speech and writing.

Yes, you could, and it is very close in meaning.

• La astronomo ĉeestas la kunvenon = The astronomer is attending the meeting / is present at the meeting
• La astronomo estas ĉe la kunveno = The astronomer is at the meeting

The second version is a little more literally is at the meeting, while ĉeestas is a standard verb meaning attend / be present at. In many contexts, the difference is small.

A helpful pronunciation guide:

• ĉ sounds like ch in church
• e is like e in met
• Esperanto stress is always on the second-to-last syllable

So:

• ĉe-es-tas

The stress falls on ES:

• ĉe-ES-tas

And in kunvenon:

• kun-ve-non
• stress on VE: kun-VE-non

So the whole sentence is pronounced roughly like:

la as-tro-NO-mo ĉe-ES-tas la kun-VE-non

In Esperanto, nouns normally end in -o.

So:

• astronomo = astronomer
• kunveno = meeting

When a noun is a direct object, it gets -n:

• kunvenon

So you can think of it like this:

• -o = noun
• -on = noun used as a direct object

This is one of the most important patterns in Esperanto grammar.